Brain Studies on Porn Users & Sex Addicts

This page contains two lists (1) neuroscience-based commentaries & reviews of the literature, and, (2) neurological studies assessing the brain structure and functioning of Internet porn users and sex/porn addicts (Compulsive Sexual Behavior Disorder).

To date, all but one of the 61 neurological studies published offers support for the addiction model (no studies falsify the porn addiction model). The results of these 60 neurological studies (and upcoming studies) are consistent with hundreds of Internet addiction “brain studies”, some of which also include internet porn use. All support the premise that internet porn use can cause addiction-related brain changes, as do over 60 studies reporting escalation/tolerance (habituation) and withdrawal symptoms.

The page begins with the following 34 recent neuroscience-based commentaries & reviews of the literature (listed by date of publication):

Reviews of the Literature & Commentaries:

1) Neuroscience of Internet Pornography Addiction: A Review and Update (Love et al., 2015). A thorough review of the neuroscience literature related to Internet addiction sub-types, with special focus on internet porn addiction. The review also critiques two headline-grabbing EEG studies by teams headed by Nicole Prause (who falsely claims the findings cast doubt on porn addiction). Excerpts:

Many recognize that several behaviors potentially affecting the reward circuitry in human brains lead to a loss of control and other symptoms of addiction in at least some individuals. Regarding Internet addiction, neuroscientific research supports the assumption that underlying neural processes are similar to substance addiction… Within this review, we give a summary of the concepts proposed underlying addiction and give an overview about neuroscientific studies on Internet addiction and Internet gaming disorder. Moreover, we reviewed available neuroscientific literature on Internet pornography addiction and connect the results to the addiction model. The review leads to the conclusion that Internet pornography addiction fits into the addiction framework and shares similar basic mechanisms with substance addiction.

2) Sex Addiction as a Disease: Evidence for Assessment, Diagnosis, and Response to Critics (Phillips et al., 2015), which provides a chart that takes on specific criticisms of porn/sex addiction, offering citations that counter them. Excerpts:

As seen throughout this article, the common criticisms of sex as a legitimate addiction do not hold up when compared to the movement within the clinical and scientific communities over the past few decades. There is ample scientific evidence and support for sex as well as other behaviors to be accepted as addiction. This support is coming from multiple fields of practice and offers incredible hope to truly embrace change as we better understand the problem. Decades of research and developments in the field of addiction medicine and neuroscience reveal the underlying brain mechanisms involved in addiction. Scientists have identified common pathways affected by addictive behavior as well as differences between the brains of addicted and non-addicted individuals, revealing common elements of addiction, regardless of the substance or behavior. However, there remains a gap between the scientific advances and the understanding by the general public, public policy, and treatment advances.

3) Cybersex Addiction (Brand & Laier, 2015). Excerpts:

Many individuals use cybersex applications, particularly Internet pornography. Some individuals experience a loss of control over their cybersex use and report that they cannot regulate their cybersex use even if they experienced negative consequences. In recent articles, cybersex addiction is considered a specific type of Internet addiction. Some current studies investigated parallels between cybersex addiction and other behavioral addictions, such as Internet Gaming Disorder. Cue-reactivity and craving are considered to play a major role in cybersex addiction. Also, neurocognitive mechanisms of development and maintenance of cybersex addiction primarily involve impairments in decision making and executive functions. Neuroimaging studies support the assumption of meaningful commonalities between cybersex addiction and other behavioral addictions as well as substance dependency.

4) Neurobiology of Compulsive Sexual Behavior: Emerging Science (Kraus et al., 2016). Excerpts:

Although not included in DSM-5, compulsive sexual behavior (CSB) can be diagnosed in ICD-10 as an impulse control disorder. However, debate exists about CSB’s classification. Additional research is needed to understand how neurobiological features relate to clinically relevant measures like treatment outcomes for CSB. Classifying CSB as a ‘behavioral addiction’ would have significant implications for policy, prevention and treatment efforts….. Given some similarities between CSB and drug addictions, interventions effective for addictions may hold promise for CSB, thus providing insight into future research directions to investigate this possibility directly.

5) Should Compulsive Sexual Behavior be Considered an Addiction? (Kraus et al., 2016). Excerpts:

With the release of DSM-5, gambling disorder was reclassified with substance use disorders. This change challenged beliefs that addiction occurred only by ingesting of mind-altering substances and has significant implications for policy, prevention and treatment strategies. Data suggest that excessive engagement in other behaviors (e.g. gaming, sex, compulsive shopping) may share clinical, genetic, neurobiological and phenomenological parallels with substance addictions.

Another area needing more research involves considering how technological changes may be influencing human sexual behaviors. Given that data suggest that sexual behaviors are facilitated through Internet and smartphone applications, additional research should consider how digital technologies relate to CSB (e.g. compulsive masturbation to Internet pornography or sex chatrooms) and engagement in risky sexual behaviors (e.g. condomless sex, multiple sexual partners on one occasion).

Overlapping features exist between CSB and substance use disorders. Common neurotransmitter systems may contribute to CSB and substance use disorders, and recent neuroimaging studies highlight similarities relating to craving and attentional biases. Similar pharmacological and psychotherapeutic treatments may be applicable to CSB and substance addictions.

6) Neurobiological Basis of Hypersexuality (Kuhn & Gallinat, 2016). Excerpts:

Behavioral addictions and in particular hypersexuality should remind us of the fact that addictive behavior actually relies on our natural survival system. Sex is an essential component in survival of species since it is the pathway for reproduction. Therefore it is extremely important that sex is considered pleasurable and has primal rewarding properties, and although it may turn into an addiction at which point sex may be pursued in a dangerous and counterproductive way, the neural basis for addiction might actually serve very important purposes in primal goal pursuit of individuals…. Taken together, the evidence seems to imply that alterations in the frontal lobe, amygdala, hippocampus, hypothalamus, septum, and brain regions that process reward play a prominent role in the emergence of hypersexuality. Genetic studies and neuropharmacological treatment approaches point at an involvement of the dopaminergic system.

7) Compulsive Sexual Behaviour as a Behavioural Addiction: The Impact of the Internet and Other Issues (Griffiths, 2016). Excerpts:

I have carried out empirical research into many different behavioural addictions (gambling, video-gaming, internet use, exercise, sex, work, etc.) and have argued that some types of problematic sexual behaviour can be classed as sex addiction, depending upon the definition of addiction used….

Whether problematic sexual behaviour is described as compulsive sexual behavior (CSB), sex addiction and/or hypersexual disorder, there are thousands of psychological therapists around the world who treat such disorders. Consequently, clinical evidence from those who help and treat such individuals should be given greater credence by the psychiatric community….

Arguably the most important development in the field of CSB and sex addiction is how the internet is changing and facilitating CSB. This was not mentioned until the concluding paragraph, yet research into online sex addiction (while comprising a small empirical base) has existed since the late 1990s, including sample sizes of up to almost 10 000 individuals. In fact, there have been recent reviews of empirical data concerning online sex addiction and treatment. These have outlined the many specific features of the internet that may facilitate and stimulate addictive tendencies in relation to sexual behaviour (accessibility, affordability, anonymity, convenience, escape, disinhibition, etc.).

8) Searching for Clarity in Muddy Water: Future Considerations for Classifying Compulsive Sexual Behavior as An Addiction (Kraus et al., 2016). Excerpts:

We recently considered evidence for classifying compulsive sexual behavior (CSB) as a non-substance (behavioral) addiction. Our review found that CSB shared clinical, neurobiological and phenomenological parallels with substance-use disorders….

Although the American Psychiatric Association rejected hypersexual disorder from DSM-5, a diagnosis of CSB (excessive sex drive) can be made using ICD-10. CSB is also being considered by ICD-11, although its ultimate inclusion is not certain. Future research should continue to build knowledge and strengthen a framework for better understanding CSB and translating this information into improved policy, prevention, diagnosis, and treatment efforts to minimize the negative impacts of CSB.

9) Is Internet Pornography Causing Sexual Dysfunctions? A Review With Clinical Reports (Park et al., 2016). An extensive review of the literature related to porn-induced sexual problems. Involving 7 US Navy doctors and Gary Wilson, the review provides the latest data revealing a tremendous rise in youthful sexual problems. It also reviews the neurological studies related to porn addiction and sexual conditioning via Internet porn. The doctors provide 3 clinical reports of men who developed porn-induced sexual dysfunctions. A second 2016 paper by Gary Wilson discusses the importance of studying the effects of porn by having subjects abstain from porn use: Eliminate Chronic Internet Pornography Use to Reveal Its Effects (2016). Excerpts:

Traditional factors that once explained men’s sexual difficulties appear insufficient to account for the sharp rise in erectile dysfunction, delayed ejaculation, decreased sexual satisfaction, and diminished libido during partnered sex in men under 40. This review (1) considers data from multiple domains, e.g., clinical, biological (addiction/urology), psychological (sexual conditioning), sociological; and (2) presents a series of clinical reports, all with the aim of proposing a possible direction for future research of this phenomenon. Alterations to the brain’s motivational system are explored as a possible etiology underlying pornography-related sexual dysfunctions.

This review also considers evidence that Internet pornography’s unique properties (limitless novelty, potential for easy escalation to more extreme material, video format, etc.) may be potent enough to condition sexual arousal to aspects of Internet pornography use that do not readily transition to real-life partners, such that sex with desired partners may not register as meeting expectations and arousal declines. Clinical reports suggest that terminating Internet pornography use is sometimes sufficient to reverse negative effects, underscoring the need for extensive investigation using methodologies that have subjects remove the variable of Internet pornography use.

3.4. Neuroadaptations Related to Internet Pornography-Induced Sexual Difficulties: We hypothesize that pornography-induced sexual difficulties involve both hyperactivity and hypoactivity in the brain’s motivational system [72, 129] and neural correlates of each, or both, have been identified in recent studies on Internet pornography users [31, 48, 52, 53, 54, 86, 113, 114, 115, 120, 121, 130, 131, 132, 133, 134].

10) Integrating Psychological and Neurobiological Considerations Regarding The Development and Maintenance of Specific Internet-Use Disorders: An Interaction of Person-Affect-Cognition-Execution model (Brand et al., 2016). A review of the mechanisms underlying the development and maintenance of specific Internet-use disorders, including “Internet-pornography-viewing disorder”. The authors suggest that pornography addiction (and cybersex addiction) be classified as internet use disorders and placed with other behavioral addictions under substance-use disorders as addictive behaviors. Excerpts:

Although the DSM-5 focuses on Internet gaming, a meaningful number of authors indicate that treatment-seeking individuals may also use other Internet applications or sites addictively….

From the current state of research, we suggest to include Internet-use disorders in the upcoming ICD-11. It is important to note that beyond Internet-gaming disorder, other types of applications are also used problematically. One approach could involve the introduction of a general term of Internet-use disorder, which could then be specified considering the first-choice application that is used (for example Internet-gaming disorder, Internet-gambling disorder, Internet-pornography-use disorder, Internet-communication disorder, and Internet-shopping disorder).

11) The Neurobiology of Sexual Addiction: Chapter from Neurobiology of Addictions, Oxford Press (Hilton et al., 2016) – Excerpts:

We review the neurobiological basis for addiction, including natural or process addiction, and then discuss how this relates to our current understanding of sexuality as a natural reward that can become functionally “unmanageable” in an individual’s life….

It is clear that the current definition and understanding of addiction has changed based with the infusion of knowledge regarding how the brain learns and desires. Whereas sexual addiction was formerly defined based solely on behavioral criteria, it is now seen also through the lens of neuromodulation. Those who will not or cannot understand these concepts may continue to cling to a more neurologically naïve perspective, but those who are able to comprehend the behavior in the context of the biology, this new paradigm provides an integrative and functional definition of sexual addiction which informs both the scientist and the clinician.

12) Neuroscientific Approaches to Online Pornography Addiction (Stark & Klucken, 2017) – Excerpts:

The availability of pornographic material has substantially increased with the development of the Internet. As a result of this, men ask for treatment more often because their pornography consumption intensity is out of control; i.e., they are not able to stop or reduce their problematic behavior although they are faced with negative consequences…. In the last two decades, several studies with neuroscientific approaches, especially functional magnetic resonance imaging (fMRI), were conducted to explore the neural correlates of watching pornography under experimental conditions and the neural correlates of excessive pornography use. Given previous results, excessive pornography consumption can be connected to already known neurobiological mechanisms underlying the development of substance-related addictions.

Finally, we summarized the studies, which investigated the correlates of excessive pornography consumption on a neural level. Despite a lack of longitudinal studies, it is plausible that the observed characteristics in men with sexual addiction are the results not the causes of excessive pornography consumption. Most of the studies report stronger cue reactivity in the reward circuit toward sexual material in excessive pornography users than in control subjects, which mirrors the findings of substance-related addictions. The results concerning a reduced prefrontal-striatal-connectivity in subjects with pornography addiction can be interpreted as a sign of an impaired cognitive control over the addictive behavior.

13) Is excessive sexual behaviour an addictive disorder? (Potenza et al., 2017) – Excerpts:

Compulsive sexual behaviour disorder (operationalised as hypersexual disorder) was considered for inclusion in DSM-5 but ultimately excluded, despite the generation of formal criteria and field trial testing. This exclusion has hindered prevention, research, and treatment efforts, and left clinicians without a formal diagnosis for compulsive sexual behaviour disorder.

Research into the neurobiology of compulsive sexual behaviour disorder has generated findings relating to attentional biases, incentive salience attributions, and brain-based cue reactivity that suggest substantial similarities with addictions. Compulsive sexual behaviour disorder is being proposed as an impulse-control disorder in ICD-11, consistent with a proposed view that craving, continued engagement despite adverse consequences, compulsive engagement, and diminished control represent core features of impulse-control disorders.

This view might have been appropriate for some DSM-IV impulse-control disorders, specifically pathological gambling. However, these elements have long been considered central to addictions, and in the transition from DSM-IV to DSM-5, the category of Impulse Control Disorders Not Elsewhere Classified was restructured, with pathological gambling renamed and reclassified as an addictive disorder. At present, the ICD-11 beta draft site lists the impulse-control disorders, and includes compulsive sexual behaviour disorder, pyromania, kleptomania, and intermittent explosive disorder.

Compulsive sexual behaviour disorder seems to fit well with non-substance addictive disorders proposed for ICD-11, consistent with the narrower term of sex addiction currently proposed for compulsive sexual behaviour disorder on the ICD-11 draft website. We believe that classification of compulsive sexual behaviour disorder as an addictive disorder is consistent with recent data and might benefit clinicians, researchers, and individuals suffering from and personally affected by this disorder.

14) Neurobiology of Pornography Addiction – A clinical review (De Sousa & Lodha, 2017) – Excerpts:

The review first looks at the basic neurobiology of addiction with the basic reward circuit and structures involved generally in any addiction. The focus then shifts to pornography addiction and studies done on the neurobiology of the condition are reviewed. The role of dopamine in pornography addiction is reviewed along with the role of certain brain structures as seen on MRI studies. fMRI studies involving visual sexual stimuli have been used widely to study the neuroscience behind pornography usage and the findings from these studies are highlighted. The effect of pornography addiction on higher order cognitive functions and executive function is also stressed.

In total, 59 articles were identified which included reviews, mini reviews and original research papers on the issues of pornography usage, addiction and neurobiology. The research papers reviewed here were centered on those that elucidated a neurobiological basis for pornography addiction. We included studies that had decent sample size and sound methodology with appropriate statistical analysis. There were some studies with fewer participants, case series, case reports and qualitative studies that were also analyzed for this paper. Both the authors reviewed all the papers and the most relevant ones were chosen for this review. This was further supplemented with the personal clinical experience of both the authors who work regularly with patients where pornography addiction and viewing is a distressing symptom. The authors also have psychotherapeutic experience with these patients that have added value to the neurobiological understanding.

15) The Proof of the Pudding Is in the Tasting: Data Are Needed to Test Models and Hypotheses Related to Compulsive Sexual Behaviors (Gola & Potenza, 2018) – Excerpts:

As described elsewhere (Kraus, Voon, & Potenza, 2016a), there is an increasing number of publications on CSB, reaching over 11,400 in 2015. Nonetheless, fundamental questions on the conceptualization of CSB remain unanswered (Potenza, Gola, Voon, Kor, & Kraus, 2017). It would be relevant to consider how the DSM and the International Classification of Diseases (ICD) operate with respect to definition and classification processes. In doing so, we think it is relevant to focus on gambling disorder (also known as pathological gambling) and how it was considered in DSM-IV and DSM-5 (as well as in ICD-10 and the forthcoming ICD-11). In DSM-IV, pathological gambling was categorized as an “Impulse-Control Disorder Not Elsewhere Classified.” In DSM-5, it was reclassified as a “Substance-Related and Addictive Disorder.”…. A similar approach should be applied to CSB, which is currently being considered for inclusion as an impulse-control disorder in ICD-11 (Grant et al., 2014; Kraus et al., 2018)….

Among the domains that may suggest similarities between CSB and addictive disorders are neuroimaging studies, with several recent studies omitted by Walton et al. (2017). Initial studies often examined CSB with respect to models of addiction (reviewed in Gola, Wordecha, Marchewka, & Sescousse, 2016b; Kraus, Voon, & Potenza, 2016b). A prominent model—the incentive salience theory (Robinson & Berridge, 1993)—states that in individuals with addictions, cues associated with substances of abuse may acquire strong incentive values and evoke craving. Such reactions may relate to activations of brain regions implicated in reward processing, including the ventral striatum. Tasks assessing cue reactivity and reward processing may be modified to investigate the specificity of cues (e.g., monetary versus erotic) to specific groups (Sescousse, Barbalat, Domenech, & Dreher, 2013), and we have recently applied this task to study a clinical sample (Gola et al., 2017).

We found that individuals seeking treatment for problematic pornography use and masturbation, when compared to matched (by age, gender, income, religiosity, amount of sexual contacts with partners, sexual arousability) healthy control subjects, showed increased ventral striatal reactivity for cues of erotic rewards, but not for associated rewards and not for monetary cues and rewards. This pattern of brain reactivity is in line with the incentive salience theory and suggests that a key feature of CSB may involve cue reactivity or craving induced by initially neutral cues associated with sexual activity and sexual stimuli.

Additional data suggest that other brain circuits and mechanisms may be involved in CSB, and these may include anterior cingulate, hippocampus and amygdala (Banca et al., 2016; Klucken, Wehrum-Osinsky, Schweckendiek, Kruse, & Stark, 2016; Voon et al., 2014). Among these, we have hypothesized that the extended amygdala circuit that relates to high reactivity for threats and anxiety may be particularly clinically relevant (Gola, Miyakoshi, & Sescousse, 2015; Gola & Potenza, 2016) based on observation that some CSB individuals present with high levels of anxiety (Gola et al., 2017) and CSB symptoms may be reduced together with pharmacological reduction in anxiety (Gola & Potenza, 2016)…

16) Promoting educational, classification, treatment, and policy initiatives Commentary on: Compulsive sexual behaviour disorder in the ICD-11 (Kraus et al., 2018) – The world’s most widely used medical diagnostic manual, The International Classification of Diseases (ICD-11), contains a new diagnosis suitable for porn addiction: “Compulsive Sexual Behavior Disorder.” Excerpts:

For many individuals who experience persistent patterns of difficulty or failures in controlling intense, repetitive sexual impulses or urges that result in sexual behavior associated with marked distress or impairment in personal, family, social, educational, occupational, or other important areas of functioning, it is very important to be able to name and identify their problem. It is also important that care providers (i.e., clinicians and counselors) from whom individuals may seek help are familiar with CSBs. During our studies involving over 3,000 subjects seeking treatment for CSB, we have frequently heard that individuals suffering from CSB encounter multiple barriers during their seeking of help or in contact with clinicians (Dhuffar & Griffiths, 2016).

Patients report that clinicians may avoid the topic, state that such problems do not exist, or suggest that one has a high sexual drive, and should accept it instead of treating (despite that for these individuals, the CSBs may feel ego-dystonic and lead to multiple negative consequences). We believe that well-defined criteria for CSB disorder will promote educational efforts including development of training programs on how to assess and treat individuals with symptoms of CSB disorder. We hope that such programs will become a part of clinical training for psychologists, psychiatrists, and other providers of mental health care services, as well as other care providers including primary care providers, such as generalist physicians.

Basic questions on how best to conceptualize CSB disorder and provide effective treatments should be addressed. The current proposal of classifying CSB disorder as an impulse-control disorder is controversial as alternate models have been proposed (Kor, Fogel, Reid, & Potenza, 2013). There are data suggesting that CSB shares many features with addictions (Kraus et al., 2016), including recent data indicating increased reactivity of reward-related brain regions in response to cues associated with erotic stimuli (Brand, Snagowski, Laier, & Maderwald, 2016; Gola, Wordecha, Marchewka, & Sescousse, 2016; Gola et al., 2017; Klucken, Wehrum-Osinsky, Schweckendiek, Kruse, & Stark, 2016; Voon et al., 2014).

Furthermore, preliminary data suggest that naltrexone, a medication with indications for alcohol- and opioid-use disorders, may be helpful for treating CSBs (Kraus, Meshberg-Cohen, Martino, Quinones, & Potenza, 2015; Raymond, Grant, & Coleman, 2010). With respect to CSB disorder’s proposed classification as an impulse-control disorder, there are data suggesting that individuals seeking treatment for one form of CSB disorder, problematic pornography use, do not differ in terms of impulsivity from the general population. They are instead presented with increased anxiety (Gola, Miyakoshi, & Sescousse, 2015; Gola et al., 2017), and pharmacological treatment targeting anxiety symptoms may be helpful in reducing some CSB symptoms (Gola & Potenza, 2016). While it may not yet be possible to draw definitive conclusions regarding classification, more data seem to support classification as an addictive disorder when compared to an impulse-control disorder (Kraus et al., 2016), and more research is needed to examine relationships with other psychiatric conditions (Potenza et al., 2017).

17) Compulsive Sexual Behavior in Humans and Preclinical Models (2018) – Excerpts:

Compulsive sexual behavior (CSB) is widely regarded as a “behavioral addiction,” and is a major threat to quality of life and both physical and mental health. However, CSB has been slow to be recognized clinically as a diagnosable disorder. CSB is co-morbid with affective disorders as well as substance use disorders, and recent neuroimaging studies have demonstrated shared or overlapping neural pathologies disorders, especially in brain regions controlling motivational salience and inhibitory control. Clinical neuroimaging studies are reviewed that have identified structural and/or function changes in prefrontal cortex, amygdala, striatum, and thalamus in individuals suffering from CSB. A preclinical model to study the neural underpinnings of CSB in male rats is discussed consisting of a conditioned aversion procedure to examine seeking of sexual behavior despite known negative consequences.

Because CSB shares characteristics with other compulsive disorders, namely, drug addiction, comparisons of findings in CSB, and drug-addicted subjects, may be valuable to identify common neural pathologies mediating comorbidity of these disorders. Indeed, many studies have shown similar patterns of neural activity and connectivity within limbic structures that are involved in both CSB and chronic drug use [87–89].

In conclusion, this review summarized the behavioral and neuroimaging studies on human CSB and comorbidity with other disorders, including substance abuse. Together, these studies indicate that CSB is associated with functional alterations in dorsal anterior cingulate and prefrontal cortex, amygdala, striatum, and thalamus, in addition to decreased connectivity between amygdala and prefrontal cortex. Moreover, a preclinical model for CSB in male rats was described, including new evidence of neural alterations in mPFC and OFC that are correlated with loss of inhibitory control of sexual behavior. This preclinical model offers a unique opportunity to test key hypotheses to identify predispositions and underlying causes of CSB and comorbidity with other disorders.

18) Sexual Dysfunctions in the Internet Era (2018) – Excerpt:

Low sexual desire, reduced satisfaction in sexual intercourse, and erectile dysfunction (ED) are increasingly common in young population. In an Italian study from 2013, up to 25% of subjects suffering from ED were under the age of 40 [1], and in a similar study published in 2014, more than half of Canadian sexually experienced men between the age of 16 and 21 suffered from some kind of sexual disorder [2]. At the same time, prevalence of unhealthy lifestyles associated with organic ED has not changed significantly or has decreased in the last decades, suggesting that psychogenic ED is on the rise [3].

The DSM-IV-TR defines some behaviors with hedonic qualities, such as gambling, shopping, sexual behaviors, Internet use, and video game use, as “impulse control disorders not elsewhere classified”—although these are often described as behavioral addictions [4]. Recent investigation has suggested the role of behavioral addiction in sexual dysfunctions: alterations in neurobiological pathways involved in sexual response might be a consequence of repeated, supernormal stimuli of various origins.

Among behavioral addictions, problematic Internet use and online pornography consumption are often cited as possible risk factors for sexual dysfunction, often with no definite boundary between the two phenomena. Online users are attracted to Internet pornography because of its anonymity, affordability, and accessibility, and in many cases its usage could lead users through a cybersex addiction: in these cases, users are more likely to forget the “evolutionary” role of sex, finding more excitement in self-selected sexually explicit material than in intercourse.

In literature, researchers are discordant about positive and negative function of online pornography. From the negative perspective, it represents the principal cause of compulsive masturbatory behavior, cybersex addiction, and even erectile dysfunction.

19) Neurocognitive mechanisms in compulsive sexual behavior disorder (2018) – Excerpts:

To date, most neuroimaging research on compulsive sexual behavior has provided evidence of overlapping mechanisms underlying compulsive sexual behavior and non-sexual addictions. Compulsive sexual behavior is associated with altered functioning in brain regions and networks implicated in sensitization, habituation, impulse dyscontrol, and reward processing in patterns like substance, gambling, and gaming addictions. Key brain regions linked to CSB features include the frontal and temporal cortices, amygdala, and striatum, including the nucleus accumbens.

CSBD has been included in the current version of theICD-11 as an impulse-control disorder [39]. As described by the WHO, ‘Impulse-control disorders are characterized by the repeated failure to resist an impulse, drive, or urge to perform an act that is rewarding to the person, at least in the short-term, despite consequences such as longer-term harm either to the individual or to others, marked distress about the behaviour pattern, or significant impairment in personal, family, social, educational, occupational, or other important areas of functioning’ [39]. Current findings raise important questions regarding the classification of CSBD. Many disorders characterized by impaired impulse-control are classified elsewhere in the ICD-11 (for example, gambling, gaming, and substance-use disorders are classified as being addictive disorders) [123].

20) A Current Understanding of the Behavioral Neuroscience of Compulsive Sexual Behavior Disorder and Problematic Pornography Use (2018) – Excerpts:

Recent neurobiological studies have revealed that compulsive sexual behaviors are associated with altered processing of sexual material and differences in brain structure and function.

The findings summarized in our overview suggest relevant similarities with behavioral and substance-related addictions, which share many abnormalities found for CSBD (as reviewed in [127]). Although beyond the scope of the present report, substance and behavioral addictions are characterized by altered cue reactivity indexed by subjective, behavioral, and neurobiological measures (overviews and reviews: [128, 129, 130, 131, 132, 133]; alcohol: [134, 135]; cocaine: [136, 137]; tobacco: [138, 139]; gambling: [140, 141]; gaming: [142, 143]). Results concerning resting-state functional connectivity show similarities between CSBD and other addictions [144, 145].

Although few neurobiological studies of CSBD have been conducted to date, existing data suggest neurobiological abnormalities share communalities with other additions such as substance use and gambling disorders. Thus, existing data suggest that its classification may be better suited as a behavioral addiction rather than an impulse-control disorder.

21) Ventral Striatal Reactivity in Compulsive Sexual Behaviors (2018) – Excerpts:

Compulsive Sexual Behaviors (CSB) are a reason to seek treatment. Given this reality, the number of studies on CSB has increased substantially in the last decade and the World Health Organization (WHO) included CSB in its proposal for the upcoming ICD-11…… From our point of view, it is worth investigating whether CSB can be distinguished into two subtypes characterized by: (1) dominant interpersonal sexual behaviors, and (2) dominant solitary sexual behaviors and pornography watching (48, 49).

The amount of available studies on CSB (and sub-clinical populations of frequent pornography users) is constantly increasing. Among currently available studies, we were able to find nine publications (Table 1) which utilized functional magnetic resonance imaging. Only four of these (36–39) directly investigated processing of erotic cues and/or rewards and reported findings related to ventral striatum activations. Three studies indicate increased ventral striatal reactivity for erotic stimuli (36–39) or cues predicting such stimuli (36–39). These findings are consistent with Incentive Salience Theory (IST) (28), one of the most prominent frameworks describing brain functioning in addiction. The only support for another theoretical framework which predicts hypoactivation of the ventral striatum in addiction, RDS theory (29, 30), comes partially from one study (37), where individuals with CSB presented lower ventral striatal activation for exciting stimuli when compared to controls.

22) Online Porn Addiction: What We Know and What We Don’t—A Systematic Review (2019)– Excerpts:

In the last few years, there has been a wave of articles related to behavioral addictions; some of them have a focus on online pornography addiction. However, despite all efforts, we are still unable to profile when engaging in this behavior becomes pathological. Common problems include: sample bias, the search for diagnostic instrumentals, opposing approximations to the matter, and the fact that this entity may be encompassed inside a greater pathology (i.e., sex addiction) that may present itself with very diverse symptomatology. Behavioral addictions form a largely unexplored field of study, and usually exhibit a problematic consumption model: loss of control, impairment, and risky use.

Hypersexual disorder fits this model and may be composed of several sexual behaviors, like problematic use of online pornography (POPU). Online pornography use is on the rise, with a potential for addiction considering the “triple A” influence (accessibility, affordability, anonymity). This problematic use might have adverse effects in sexual development and sexual functioning, especially among the young population.

As far as we know, a number of recent studies support this entity as an addiction with important clinical manifestations such as sexual dysfunction and psychosexual dissatisfaction. Most of the existing work is based off on similar research done on substance addicts, based on the hypothesis of online pornography as a ‘supranormal stimulus’ akin to an actual substance that, through continued consumption, can spark an addictive disorder. However, concepts like tolerance and abstinence are not yet clearly established enough to merit the labeling of addiction, and thus constitute a crucial part of future research. For the moment, a diagnostic entity encompassing out of control sexual behavior has been included in the ICD-11 due to its current clinical relevance, and it will surely be of use to address patients with these symptoms that ask clinicians for help.

23) Occurrence and development of online porn addiction: individual susceptibility factors, strengthening mechanisms and neural mechanisms (2019) – Excerpts:

Initiation and development of cybersex addiction have two stages with classical conditioning and operant conditioning. Firstly, individuals use cybersex occasionally out of entertainment and curiosity. On this stage, use of internet devices is paired with sexual arousal and The results in classical conditioning, further leads to sensitization of cybersex-related cues which trigger intense craving. Individual vulnerabilities also facilitate sensitization of cybersex-related cues. On the second stage, individuals make use of cybersex frequently to satisfy their sexual desires or During this process, cybersex-related cognitive bias like positive expectation of cybersex and coping mechanism like using it to deal with negative emotions are positively reinforced, those personal traits associated with cybersex addiction such as narcissism, sexual sensation seeking, sexual excitability, dysfunction use of sex are also positively reinforced, while common personality disorders like nervousness, low self-esteem and psychopathologies like depression, anxiety are negatively reinforced.

Executive function deficits occur due to long-term cybersex use. Interaction of executive function deficits and intense craving promotes development and maintenance Of cybersex addiction. Researches using electrophysiological and brain imaging tools mainly to study cybersex addiction found that cybersex addicts may develop more and more robust craving for cybersex when facing cybersex-related cues, but they feel less and less pleasant when using it. Studies provide evidence for intense craving triggered by cybersex-related cues and impaired executive function.

In conclusion, people who are vulnerable to cybersex addiction can’t stop cybersex use out of more and more intense craving for cybersex and impaired executive function, but they feel less and less satisfied when using it, and search for more and more original pornographic materials online at the cost of plenty of time and money. Once they reduce cybersex use or just quit it, they would suffer from a series of adverse effects like depression, anxiety, erection dysfunction, lack of sexual arousal.

24) Theories, prevention, and treatment of pornography-use disorder (2019)– Excerpts:

Compulsive sexual behavior disorder, including problematic pornography use, has been included in the ICD-11 as impulse control disorder. The diagnostic criteria for this disorder, however, are very similar to the criteria for disorders due to addictive behaviors, for example repetitive sexual activities becoming a central focus of the personʼs life, unsuccessful efforts to significantly reduce repetitive sexual behaviors and continued repetitive sexual behaviors despite experiencing negative consequences (WHO, 2019). Many researchers and clinicians also argue that problematic pornography use can be considered a behavioral addiction.

Cue-reactivity and craving in combination with reduced inhibitory control, implicit cognitions (e.g. approach tendencies) and experiencing gratification and compensation linked to pornography use have been demonstrated in individuals with symptoms of pornography-use disorder. Neuroscientific studies confirm the involvement of addiction-related brain circuits, including the ventral striatum and other parts of fronto-striatal loops, in the development and maintenance of problematic pornography use. Case reports and proof-of-concept studies suggest the efficacy of pharmacological interventions, for example the opioid antagonist naltrexone, for treating individuals with pornography-use disorder and compulsive sexual behavior disorder.

Theoretical considerations and empirical evidence suggest that the psychological and neurobiological mechanisms involved in addictive disorders are also valid for pornography-use disorder.

25) Self-perceived Problematic Pornography Use: An Integrative Model from a Research Domain Criteria and Ecological Perspective (2019) – Excerpts

Self-perceived problematic pornography use seems to be related to multiple units of analysis and different systems in the organism. Based on the findings within the RDoC paradigm described above, it is possible to create a cohesive model in which different units of analysis impact each other (Fig. 1). It appears that elevated levels of dopamine, present in the natural activation of the reward system related to sexual activity and orgasm, interfere with the regulation of the VTA-NAc system in people who report SPPPU. This dysregulation leads to greater activation of the reward system and increased conditioning related to the use of pornography, fostering approach behavior to pornographic material due to the increase in dopamine in the nucleus accumbens.

Continued exposure to immediate and easily available pornographic material seems to create an imbalance in the mesolimbic dopaminergic system. This excess dopamine activates GABA output pathways, producing dynorphin as a byproduct, which inhibits dopamine neurons. When dopamine decreases, acetylcholine is released and can generate an aversive state (Hoebel et al. 2007), creating the negative reward system found in the second stage of addiction models. This imbalance is also correlated to the shift from approach to avoidance behavior, seen in people who report problematic pornography use…. These changes in internal and behavioral mechanisms among people with SPPPU are similar to those observed in people with substance addictions, and map into models of addiction (Love et al. 2015).

26) Cybersex addiction: an overview of the development and treatment of a newly emerging disorder (2020) – Excerpts:

Cybersex addiction is a non-substance related addiction that involves online sexual activity on the internet. Nowadays, various kinds of things related to sex or pornography are easily accessible through internet media. In Indonesia, sexuality is usually assumed taboo but most young people have been exposed to pornography. It can lead to an addiction with many negative effects on users, such as relationships, money, and psychiatric problems like major depression and anxiety disorders.

27) Which Conditions Should Be Considered as Disorders in the International Classification of Diseases (ICD-11) Designation of “Other Specified Disorders Due to Addictive Behaviors”? (2020) – A review by addiction experts concludes that pornography-use disorder is a condition that ought to be diagnosed with the ICD-11 category “other specified disorders due to addictive behaviors”. In other words, compulsive porn use looks like other recognized addictions. Excerpts:

35) Reward Responsiveness, Learning, and Valuation Implicated in Problematic Pornography Use – a Research Domain Criteria Perspective (2022) – Excerpts:

See Questionable & Misleading Studies for highly publicized papers that are not what they claim to be (this dated paper – Ley et al., 2014 – was not a literature review and misrepresented most the papers it did cite). See this page for the many studies linking porn use to sexual problems and decreased sexual & relationship satisfaction.

Neurological studies (fMRI, MRI, EEG, Neuro-endocrine, Neuro-pyschological) on porn users and sex addicts:

The neurological studies below are categorized in two ways: (1) by the addiction-related brain changes each reported, and (2) by the date of publication.

1) Listed by Addiction-Related Brain Change: The four major brain changes induced by addiction are described by George F. Koob and Nora D. Volkow in their landmark review. Koob is the Director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), and Volkow is the director of the National Institute on Drug Abuse (NIDA). It was published in The New England Journal of Medicine: Neurobiologic Advances from the Brain Disease Model of Addiction (2016). The paper describes the major brain changes involved with both drug and behavioral addictions, while stating in its opening paragraph that sex addiction exists:

“We conclude that neuroscience continues to support the brain disease model of addiction. Neuroscience research in this area not only offers new opportunities for the prevention and treatment of substance addictions and related behavioral addictions (e.g., to food, sex, and gambling)….”

The Volkow & Koob paper outlined four fundamental addiction-caused brain changes, which are: 1) Sensitization, 2) Desensitization, 3) Dysfunctional prefrontal circuits (hypofrontality), 4) Malfunctioning stress system. All 4 of these brain changes have been identified among the many neurological studies listed on this page:

• Studies reporting sensitization (cue-reactivity & cravings) in porn users/sex addicts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28.
• Studies reporting desensitization or habituation (resulting in tolerance) in porn users/sex addicts: 1, 2, 3, 4, 5, 6, 7, 8.
• Studies reporting poorer executive functioning (hypofrontality) or altered prefrontal activity in porn users/sex addicts: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19.
• Studies indicating a dysfunctional stress system in porn users/sex addicts: 1, 2, 3, 4, 5.

2) Listed by Date Of Publication: The following list contains all the neurological studies published on porn users and sex addicts. Each study listed below is accompanied by a description or excerpt, and indicates which of the 4 addiction-related brain change(s) just discussed its findings endorse:

1) Preliminary Investigation of The Impulsive And Neuroanatomical Characteristics of Compulsive Sexual Behavior (Miner et al., 2009) – [dysfunctional prefrontal circuits/poorer executive function] – A small fMRI study involving primarily sex addicts (Compulsive Sexual Behavior). Study reports more impulsive behavior in a Go-NoGo task in CSB subjects compared to control participants. Brain scans revealed that sex addicts had disorganized prefrontal cortex white matter compared to controls. Excerpts:

The data presented in this paper are consistent with the assumption that CSB has much in common with impulse control disorders, such as kleptomania, compulsive gambling, and eating disorders. Specifically, we found that individuals who meet diagnostic criteria for compulsive sexual behavior score higher on self report measures of impulsivity, including measures of overall impulsivity and the personality factor, Constraint…….. In addition to the above self-report measures, CSB patients also showed significantly more impulsivity on a behavioral task, the Go-No Go procedure.

Results also indicate that CSB patients showed significantly higher superior frontal region mean diffusivity (MD) than controls. A correlational analysis indicated significant associations between impulsivity measures and inferior frontal region fractional anisotrophy (FA) and MD, but no associations with superior frontal region measures. Similar analyses indicated a significant negative association between superior frontal lobe MD and the compulsive sexual behavior inventory.

Thus, these preliminary analyses are promising and provide an indication that there are probably neuroanatomical and/or neurophysiological factors associated with compulsive sexual behavior. These data also indicate that CSB is likely characterized by impulsivity, but also includes other components, which may be related to the emotional reactivity and anxiety of OCD.

2) Self-reported differences on measures of executive function and hypersexual behavior in a patient and community sample of men (Reid et al., 2010) – [poorer executive function] – An excerpt:

Patients seeking help for hypersexual behavior often exhibit features of impulsivity, cognitive rigidity, poor judgment, deficits in emotion regulation, and excessive preoccupation with sex. Some of these characteristics are also common among patients presenting with neurological pathology associated with executive dysfunction. These observations led to the current investigation of differences between a group of hypersexual patients (n = 87) and a non-hypersexual community sample (n = 92) of men using the Behavior Rating Inventory of Executive Function-Adult Version  Hypersexual behavior was positively correlated with global indices of executive dysfunction and several subscales of the BRIEF-A. These findings provide preliminary evidence supporting the hypothesis that executive dysfunction may be implicated in hypersexual behavior.

3) Watching Pornographic Pictures on the Internet: Role of Sexual Arousal Ratings and Psychological-Psychiatric Symptoms for Using Internet Sex Sites Excessively (Brand et al., 2011) – [greater cravings/sensitization and poorer executive function] – An excerpt:

Results indicate that self-reported problems in daily life linked to online sexual activities were predicted by subjective sexual arousal ratings of the pornographic material, global severity of psychological symptoms, and the number of sex applications used when being on Internet sex sites in daily life, while the time spent on Internet sex sites (minutes per day) did not significantly contribute to explanation of variance in IATsex score. We see some parallels between cognitive and brain mechanisms potentially contributing to the maintenance of excessive cybersex and those described for individuals with substance dependence.

4) Pornographic Picture Processing Interferes with Working Memory Performance (Laier et al., 2013) – [greater cravings/sensitization and poorer executive function] – An excerpt:

Some individuals report problems during and after Internet sex engagement, such as missing sleep and forgetting appointments, which are associated with negative life consequences. One mechanism potentially leading to these kinds of problems is that sexual arousal during Internet sex might interfere with working memory (WM) capacity, resulting in a neglect of relevant environmental information and therefore disadvantageous decision making. Results revealed worse WM performance in the pornographic picture condition of the 4-back task compared with the three remaining picture conditions. Findings are discussed with respect to Internet addiction because WM interference by addiction-related cues is well known from substance dependencies.

5) Sexual Picture Processing Interferes with Decision-Making Under Ambiguity (Laier et al., 2013) – [greater cravings/sensitization and poorer executive function] – An excerpt:

Decision-making performance was worse when sexual pictures were associated with disadvantageous card decks compared to performance when the sexual pictures were linked to the advantageous decks. Subjective sexual arousal moderated the relationship between task condition and decision-making performance. This study emphasized that sexual arousal interfered with decision-making, which may explain why some individuals experience negative consequences in the context of cybersex use.

6) Cybersex addiction: Experienced sexual arousal when watching pornography and not real-life sexual contacts makes the difference (Laier et al., 2013) – [greater cravings/sensitization and poorer executive function] – An excerpt:

The results show that indicators of sexual arousal and craving to Internet pornographic cues predicted tendencies towards cybersex addiction in the first study. Moreover, it was shown that problematic cybersex users report greater sexual arousal and craving reactions resulting from pornographic cue presentation. In both studies, the number and the quality with real-life sexual contacts were not associated to cybersex addiction. The results support the gratification hypothesis, which assumes reinforcement, learning mechanisms, and craving to be relevant processes in the development and maintenance of cybersex addiction. Poor or unsatisfying sexual real life contacts cannot sufficiently explain cybersex addiction.

7) Sexual Desire, not Hypersexuality, is Related to Neurophysiological Responses Elicited by Sexual Images (Steele et al., 2013) – [greater cue-reactivity correlated with less sexual desire: sensitization and habituation] – This EEG study was touted in the media as evidence against the existence of porn/sex addiction. Not so. Steele et al. 2013 actually lends support to the existence of both porn addiction and porn use down-regulating sexual desire. How so? The study reported higher EEG readings (relative to neutral pictures) when subjects were briefly exposed to pornographic photos. Studies consistently show that an elevated P300 occurs when addicts are exposed to cues (such as images) related to their addiction.

In line with the Cambridge University brain scan studies, this EEG study also reported greater cue-reactivity to porn correlating with less desire for partnered sex. To put it another way – individuals with greater brain activation to porn would rather masturbate to porn than have sex with a real person. Shockingly, study spokesperson Nicole Prause claimed that porn users merely had “high libido,” yet the results of the study say the exact opposite (subjects’ desire for partnered sex was dropping in relation to their porn use).

Together, these two Steele et al. findings indicate greater brain activity to cues (porn images), yet less reactivity to natural rewards (sex with a person). That”s sensitization & desensitization, which are hallmarks of an addiction. Eight peer-reviewed papers explain the truth: Peer-reviewed critiques of Steele et al., 2013. Also see this extensive YBOP critique.

Aside from the many unsupported claims in the press, it’s disturbing that Prause’s 2013 EGG study passed peer-review, as it suffered from serious methodological flaws: 1) subjects were heterogeneous (males, females, non-heterosexuals); 2) subjects were not screened for mental disorders or addictions; 3) study had no control group for comparison; 4) questionnaires were not validated for porn use or porn addiction. Steele at al. is so badly flawed that only 4 of the above 24 literature reviews & commentaries bother to mention it: two critiquing it as unacceptable junk science, while two cite it as correlating cue-reactivity with less desire for sex with a partner (signs of addiction).

8) Brain Structure and Functional Connectivity Associated With Pornography Consumption: The Brain on Porn (Kuhn & Gallinat, 2014) – [desensitization, habituation, and dysfunctional prefrontal circuits]. This Max Planck Institute fMRI study reported 3 neurological findings correlating with higher levels of porn use: (1) less reward system grey matter (dorsal striatum), (2) less reward circuit activation while briefly viewing sexual photos, (3) poorer functional connectivity between the dorsal striatum and dorsolateral prefrontal cortex. The researchers interpreted the 3 findings as an indication of the effects of longer-term porn exposure. Said the study,

This is in line with the hypothesis that intense exposure to pornographic stimuli results in a down-regulation of the natural neural response to sexual stimuli.

In describing the poorer functional connectivity between the PFC and the striatum the study said,

Dysfunction of this circuitry has been related to inappropriate behavioral choices, such as drug seeking, regardless of the potential negative outcome

Lead author Simone Kühn commenting in the Max Planck press release said:

We assume that subjects with a high porn consumption need increasing stimulation to receive the same amount of reward. That could mean that regular consumption of pornography more or less wears out your reward system. That would fit perfectly the hypothesis that their reward systems need growing stimulation.

9) Neural Correlates of Sexual Cue Reactivity in Individuals with and without Compulsive Sexual Behaviours (Voon et al., 2014) – [sensitization/cue-reactivity and desensitization] The first in a series of Cambridge University studies found the same brain activity pattern in porn addicts (CSB subjects) as seen in drug addicts and alcoholics – greater cue-reactivity or sensitization. Lead researcher Valerie Voon said:

There are clear differences in brain activity between patients who have compulsive sexual behaviour and healthy volunteers. These differences mirror those of drug addicts.

Voon et al., 2014 also found that porn addicts fit the accepted addiction model of wanting “it” more, but not liking “it” any more. Excerpt:

Compared to healthy volunteers, CSB subjects had greater subjective sexual desire or wanting to explicit cues and had greater liking scores to erotic cues, thus demonstrating a dissociation between wanting and liking

The researchers also reported that 60% of subjects (average age: 25) had difficulty achieving erections/arousal with real partners, yet could achieve erections with porn. This indicates sensitization or habituation. Excerpts:

CSB subjects reported that as a result of excessive use of sexually explicit materials….. experienced diminished libido or erectile function specifically in physical relationships with women (although not in relationship to the sexually explicit material)…

CSB subjects compared to healthy volunteers had significantly more difficulty with sexual arousal and experienced more erectile difficulties in intimate sexual relationships but not to sexually explicit material.

10) Enhanced Attentional Bias towards Sexually Explicit Cues in Individuals with and without Compulsive Sexual Behaviours (Mechelmans et al., 2014) – [sensitization/cue-reactivity] – The second Cambridge University study. An excerpt:

Our findings of enhanced attentional bias… suggest possible overlaps with enhanced attentional bias observed in studies of drug cues in disorders of addictions. These findings converge with recent findings of neural reactivity to sexually explicit cues in [porn addicts] in a network similar to that implicated in drug-cue-reactivity studies and provide support for incentive motivation theories of addiction underlying the aberrant response to sexual cues in [porn addicts]. This finding dovetails with our recent observation that sexually explicit videos were associated with greater activity in a neural network similar to that observed in drug-cue-reactivity studies. Greater desire or wanting rather than liking was further associated with activity in this neural network. These studies together provide support for an incentive motivation theory of addiction underlying the aberrant response towards sexual cues in CSB.

11) Cybersex addiction in heterosexual female users of internet pornography can be explained by gratification hypothesis (Laier et al., 2014) – [greater cravings/sensitization] – An excerpt:

We examined 51 female IPU and 51 female non-Internet pornography users (NIPU). Using questionnaires, we assessed the severity of cybersex addiction in general, as well as propensity for sexual excitation, general problematic sexual behavior, and severity of psychological symptoms. Additionally, an experimental paradigm, including a subjective arousal rating of 100 pornographic pictures, as well as indicators of craving, was conducted. Results indicated that IPU rated pornographic pictures as more arousing and reported greater craving due to pornographic picture presentation compared with NIPU. Moreover, craving, sexual arousal rating of pictures, sensitivity to sexual excitation, problematic sexual behavior, and severity of psychological symptoms predicted tendencies toward cybersex addiction in IPU.

Being in a relationship, number of sexual contacts, satisfaction with sexual contacts, and use of interactive cybersex were not associated with cybersex addiction. These results are in line with those reported for heterosexual males in previous studies. Findings regarding the reinforcing nature of sexual arousal, the mechanisms of learning, and the role of cue reactivity and craving in the development of cybersex addiction in IPU need to be discussed.

12) Empirical Evidence and Theoretical Considerations on Factors Contributing to Cybersex Addiction From a Cognitive Behavioral View (Laier et al., 2014) – [greater cravings/sensitization] – An excerpt:

The nature of a phenomenon often called cybersex addiction (CA) and its mechanisms of development are discussed. Previous work suggests that some individuals might be vulnerable to CA, while positive reinforcement and cue-reactivity are considered to be core mechanisms of CA development. In this study, 155 heterosexual males rated 100 pornographic pictures and indicated their increase of sexual arousal. Moreover, tendencies towards CA, sensitivity to sexual excitation, and dysfunctional use of sex in general were assessed. The results of the study show that there are factors of vulnerability to CA and provide evidence for the role of sexual gratification and dysfunctional coping in the development of CA.

13) Novelty, Conditioning and Attentional Bias to Sexual Rewards (Banca et al., 2015) – [greater cravings/sensitization and habituation/desensitization] – Another Cambridge University fMRI study. Compared to controls porn addicts preferred sexual novelty and conditioned cues associated porn. However, the brains of porn addicts habituated faster to sexual images. Since novelty preference wasn’t pre-existing, it is believed that porn addiction drives novelty-seeking in an attempt to overcome habituation and desensitization.

Compulsive sexual behavior (CSB) was associated with enhanced novelty preference for sexual, as compared to control images, and a generalized preference for cues conditioned to sexual and monetary versus neutral outcomes compared to healthy volunteers. CSB individuals also had greater dorsal cingulate habituation to repeated sexual versus monetary images with the degree of habituation correlating with enhanced preference for sexual novelty. Approach behaviors to sexually conditioned cues dissociable from novelty preference were associated with an early attentional bias to sexual images. This study shows that CSB individuals have a dysfunctional enhanced preference for sexual novelty possibly mediated by greater cingulate habituation along with a generalized enhancement of conditioning to rewards. An excerpt:

An excerpt from the related press release:

They found that when the sex addicts viewed the same sexual image repeatedly, compared to the healthy volunteers they experienced a greater decrease of activity in the region of the brain known as the dorsal anterior cingulate cortex, known to be involved in anticipating rewards and responding to new events. This is consistent with ‘habituation’, where the addict finds the same stimulus less and less rewarding – for example, a coffee drinker may get a caffeine ‘buzz’ from their first cup, but over time the more they drink coffee, the smaller the buzz becomes.

This same habituation effect occurs in healthy males who are repeatedly shown the same porn video. But when they then view a new video, the level of interest and arousal goes back to the original level. This implies that, to prevent habituation, the sex addict would need to seek out a constant supply of new images. In other words, habituation could drive the search for novel images.

“Our findings are particularly relevant in the context of online pornography,” adds Dr Voon. “It’s not clear what triggers sex addiction in the first place and it is likely that some people are more pre-disposed to the addiction than others, but the seemingly endless supply of novel sexual images available online helps feed their addiction, making it more and more difficult to escape.”

14) Neural Substrates of Sexual Desire in Individuals with Problematic Hypersexual Behavior (Seok & Sohn, 2015) – [greater cue reactivity/sensitization and dysfunctional prefrontal circuits] – This Korean fMRI study replicates other brain studies on porn users. Like the Cambridge University studies it found cue-induced brain activation patterns in sex addicts, which mirrored the patterns of drug addicts. In line with several German studies it found alterations in the prefrontal cortex which match the changes observed in drug addicts. What’s new is that the findings matched the prefrontal cortex activation patterns observed in drug addicts: Greater cue-reactivity to sexual images yet inhibited responses to other normally salient stimuli. An excerpt:

Our study aimed to investigate the neural correlates of sexual desire with event-related functional magnetic resonance imaging (fMRI). Twenty-three individuals with PHB and 22 age-matched healthy controls were scanned while they passively viewed sexual and nonsexual stimuli. The subjects’ levels of sexual desire were assessed in response to each sexual stimulus. Relative to controls, individuals with PHB experienced more frequent and enhanced sexual desire during exposure to sexual stimuli. Greater activation was observed in the caudate nucleus, inferior parietal lobe, dorsal anterior cingulate gyrus, thalamus, and dorsolateral prefrontal cortex in the PHB group than in the control group. In addition, the hemodynamic patterns in the activated areas differed between the groups. Consistent with the findings of brain imaging studies of substance and behavior addiction, individuals with the behavioral characteristics of PHB and enhanced desire exhibited altered activation in the prefrontal cortex and subcortical regions

15) Modulation of Late Positive Potentials by Sexual Images in Problem Users and Controls Inconsistent with “Porn Addiction” (Prause et al., 2015) – [habituation] – A second EEG study from Nicole Prause’s team. This study compared the 2013 subjects from Steele et al., 2013 to an actual control group (yet it suffered from the same methodological flaws named above). The results: Compared to controls “individuals experiencing problems regulating their porn viewing” had lower brain responses to one-second exposure to photos of vanilla porn. The lead author claims these results “debunk porn addiction.” What legitimate scientist would claim that their lone anomalous study has debunked a well established field of study?

In reality, the findings of Prause et al. 2015 align perfectly with Kühn & Gallinat (2014), which found that more porn use correlated with less brain activation in response to pictures of vanilla porn. Prause et al. findings also align with Banca et al. 2015 which is #13 in this list. Moreover, another EEG study found that greater porn use in women correlated with less brain activation to porn. Lower EEG readings mean that subjects are paying less attention to the pictures. Put simply, frequent porn users were desensitized to static images of vanilla porn. They were bored (habituated or desensitized). See this extensive YBOP critique. Ten peer-reviewed papers agree that this study actually found desensitization/habituation in frequent porn users (consistent with addiction): Peer-reviewed critiques of Prause et al., 2015

Prause proclaimed that her EEG readings assessed “cue-reactivity” (sensitization), rather than habituation. Even if Prause were correct she conveniently ignores the gaping hole in her “falsification” assertion: Even if Prause et al. 2015 had found less cue-reactivity in frequent porn users, 24 other neurological studies have reported cue-reactivity or cravings (sensitization) in compulsive porn users: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24. Science doesn’t go with the lone anomalous study hampered by serious methodological flaws; science goes with the preponderance of evidence (unless you are agenda-driven).

16) HPA Axis Dysregulation in Men With Hypersexual Disorder (Chatzittofis, 2015) – [dysfunctional stress response] – A study with 67 male sex addicts and 39 age-matched controls. The Hypothalamus-Pituitary-Adrenal (HPA) axis is the central player in our stress response. Addictions alter the brain’s stress circuits leading to a dysfunctional HPA axis. This study on sex addicts (hypersexuals) found altered stress responses that mirror the findings with substance addictions. Excerpts from press release:

The study involved 67 men with hypersexual disorder and 39 healthy matched controls. The participants were carefully diagnosed for hypersexual disorder and any co-morbidity with depression or childhood trauma. The researchers gave them a low dose of dexamethasone on the evening before the test to inhibit their physiological stress response, and then in the morning measured their levels of stress hormones cortisol and ACTH. They found that patients with hypersexual disorder had higher levels of such hormones than the healthy controls, a difference that remained even after controlling for co-morbid depression and childhood trauma.

“Aberrant stress regulation has previously been observed in depressed and suicidal patients as well as in substance abusers,” says Professor Jokinen. “In recent years, the focus has been on whether childhood trauma can lead to a dysregulation of the body’s stress systems via so-called epigenetic mechanisms, in other words how their psychosocial environments can influence the genes that control these systems.” According to the researchers, the results suggest that the same neurobiological system involved in another type of abuse can apply to people with hypersexual disorder.

17) Prefrontal control and internet addiction: a theoretical model and review of neuropsychological and neuroimaging findings (Brand et al., 2015) – [dysfunctional prefrontal circuits/poorer executive function and sensitization] – Excerpt:

Consistent with this, results from functional neuroimaging and other neuropsychological studies demonstrate that cue-reactivity, craving, and decision making are important concepts for understanding Internet addiction. The findings on reductions in executive control are consistent with other behavioral addictions, such as pathological gambling. They also emphasize the classification of the phenomenon as an addiction, because there are also several similarities with findings in substance dependency.  Moreover, the results of the current study are comparable to findings from substance dependency research and emphasize analogies between cybersex addiction and substance dependencies or other behavioral addictions.

18) Implicit associations in cybersex addiction: Adaption of an Implicit Association Test with pornographic pictures (Snagkowski et al., 2015) – [greater cravings/sensitization] – Excerpt:

Recent studies show similarities between cybersex addiction and substance dependencies and argue to classify cybersex addiction as a behavioral addiction. In substance dependency, implicit associations are known to play a crucial role, and such implicit associations have not been studied in cybersex addiction, so far. In this experimental study, 128 heterosexual male participants completed an Implicit Association Test (IAT; Greenwald, McGhee, & Schwartz, 1998) modified with pornographic pictures. Further, problematic sexual behavior, sensitivity towards sexual excitation, tendencies towards cybersex addiction, and subjective craving due to watching pornographic pictures were assessed.

Results show positive relationships between implicit associations of pornographic pictures with positive emotions and tendencies towards cybersex addiction, problematic sexual behavior, sensitivity towards sexual excitation as well as subjective craving. Moreover, a moderated regression analysis revealed that individuals who reported high subjective craving and showed positive implicit associations of pornographic pictures with positive emotions, particularly tended towards cybersex addiction. The findings suggest a potential role of positive implicit associations with pornographic pictures in the development and maintenance of cybersex addiction. Moreover, the results of the current study are comparable to findings from substance dependency research and emphasize analogies between cybersex addiction and substance dependencies or other behavioral addictions.

19) Symptoms of cybersex addiction can be linked to both approaching and avoiding pornographic stimuli: results from an analog sample of regular cybersex users (Snagkowski, et al., 2015) – [greater cravings/sensitization] – Excerpt:

Some approaches point toward similarities to substance dependencies for which approach/avoidance tendencies are crucial mechanisms. Several researchers have argued that within an addiction-related decision situation, individuals might either show tendencies to approach or avoid addiction-related stimuli. In the current study 123 heterosexual males completed an Approach-Avoidance-Task (AAT; Rinck and Becker, 2007) modified with pornographic pictures. During the AAT participants either had to push pornographic stimuli away or pull them toward themselves with a joystick. Sensitivity toward sexual excitation, problematic sexual behavior, and tendencies toward cybersex addiction were assessed with questionnaires.

Results showed that individuals with tendencies toward cybersex addiction tended to either approach or avoid pornographic stimuli. Additionally, moderated regression analyses revealed that individuals with high sexual excitation and problematic sexual behavior who showed high approach/avoidance tendencies, reported higher symptoms of cybersex addiction. Analogous to substance dependencies, results suggest that both approach and avoidance tendencies might play a role in cybersex addiction. Moreover, an interaction with sensitivity toward sexual excitation and problematic sexual behavior could have an accumulating effect on the severity of subjective complaints in everyday life due to cybersex use. The findings provide further empirical evidence for similarities between cybersex addiction and substance dependencies. Such similarities could be retraced to a comparable neural processing of cybersex- and drug-related cues.

20) Getting stuck with pornography? Overuse or neglect of cybersex cues in a multitasking situation is related to symptoms of cybersex addiction (Schiebener et al., 2015) – [greater cravings/sensitization and poorer executive control] – Excerpt:

Some individuals consume cybersex contents, such as pornographic material, in an addictive manner, which leads to severe negative consequences in private life or work. One mechanism leading to negative consequences may be reduced executive control over cognition and behavior that may be necessary to realize goal-oriented switching between cybersex use and other tasks and obligations of life. To address this aspect, we investigated 104 male participants with an executive multitasking paradigm with two sets: One set consisted of pictures of persons, the other set consisted of pornographic pictures. In both sets the pictures had to be classified according to certain criteria. The explicit goal was to work on all classification tasks to equal amounts, by switching between the sets and classification tasks in a balanced manner.

We found that less balanced performance in this multitasking paradigm was associated with a higher tendency towards cybersex addiction. Persons with this tendency often either overused or neglected working on the pornographic pictures. The results indicate that reduced executive control over multitasking performance, when being confronted with pornographic material, may contribute to dysfunctional behaviors and negative consequences resulting from cybersex addiction. However, individuals with tendencies towards cybersex addiction seem to have either an inclination to avoid or to approach the pornographic material, as discussed in motivational models of addiction.

21) Trading Later Rewards for Current Pleasure: Pornography Consumption and Delay Discounting (Negash et al., 2015) – [poorer executive control: causation experiment] – Excerpts:

Study 1: Participants completed a pornography use questionnaire and a delay discounting task at Time 1 and then again four weeks later. Participants reporting higher initial pornography use demonstrated a higher delay discounting rate at Time 2, controlling for initial delay discounting. Study 2:  Participants who abstained from pornography use demonstrated lower delay discounting than participants who abstained from their favorite food.

Internet pornography is a sexual reward that contributes to delay discounting differently than other natural rewards do, even when use is not compulsive or addictive. This research makes an important contribution, demonstrating that the effect goes beyond temporary arousal.

Pornography consumption may provide immediate sexual gratification but can have implications that transcend and affect other domains of a person’s life, especially relationships.

The finding suggests that Internet pornography is a sexual reward that contributes to delay discounting differently than other natural rewards. It is therefore important to treat pornography as a unique stimulus in reward, impulsivity, and addiction studies and to apply this accordingly in individual as well as relational treatment.

22) Sexual Excitability and Dysfunctional Coping Determine Cybersex Addiction in Homosexual Males (Laier et al., 2015) – [greater cravings/sensitization] – Excerpt:

Recent findings have demonstrated an association between CyberSex Addiction (CA) severity and indicators of sexual excitability, and that coping by sexual behaviors mediated the relationship between sexual excitability and CA symptoms. The aim of this study was to test this mediation in a sample of homosexual males. Questionnaires assessed symptoms of CA, sensitivity to sexual excitation, pornography use motivation, problematic sexual behavior, psychological symptoms, and sexual behaviors in real life and online. Moreover, participants viewed pornographic videos and indicated their sexual arousal before and after the video presentation.

Results showed strong correlations between CA symptoms and indicators of sexual arousal and sexual excitability, coping by sexual behaviors, and psychological symptoms. CA was not associated with offline sexual behaviors and weekly cybersex use time. Coping by sexual behaviors partially mediated the relationship between sexual excitability and CA. The results are comparable with those reported for heterosexual males and females in previous studies and are discussed against the background of theoretical assumptions of CA, which highlight the role of positive and negative reinforcement due to cybersex use.

23) The Role of Neuroinflammation in the Pathophysiology of Hypersexual Disorder (Jokinen et al., 2016) – [dysfunctional stress response and neuro-inflammation] – This study reported higher levels of circulating Tumor Necrosis Factor (TNF) in sex addicts when compared to healthy controls. Elevated levels of TNF (a marker of inflammation) have also been found in substance abusers and drug-addicted animals (alcohol, heroin, meth). There were strong correlations between TNF levels and rating scales measuring hypersexuality.

24) Compulsive Sexual Behavior: Prefrontal And Limbic Volume and Interactions (Schmidt et al., 2016) – [dysfunctional prefrontal circuits and sensitization] – This is an fMRI study. Compared to healthy controls CSB subjects (porn addicts) had increased left amygdala volume and reduced functional connectivity between the amygdala and dorsolateral prefrontal cortex DLPFC. Reduced functional connectivity between the amygdala and the prefrontal cortex aligns with substance addictions. It is thought that poorer connectivity diminishes the prefrontal cortex’s control over a user’s impulse to engage in the addictive behavior. This study suggests that drug toxicity may lead to less grey matter and thus reduced amygdala volume in drug addicts. The amygdala is consistently active during porn viewing, especially during initial exposure to a sexual cue. Perhaps the constant sexual novelty and searching and seeking leads to a unique effect on the amygdala in compulsive porn users. Alternatively, years of porn addiction and severe negative consequences are very stressful – and chronic social stress is related to increased amygdala volume. Study #16 above found that “sex addicts” have an overactive stress system. Could the chronic stress related to porn/sex addiction, along with factors that make sex unique, lead to greater amygdala volume? An excerpt:

Our current findings highlight elevated volumes in a region implicated in motivational salience and lower resting state connectivity of prefrontal top-down regulatory control networks. Disruption of such networks may explain the aberrant behavioral patterns toward environmentally salient reward or enhanced reactivity to salient incentive cues. Although our volumetric findings contrast with those in SUD, these findings may reflect differences as a function of the neurotoxic effects of chronic drug exposure. Emerging evidence suggests potential overlaps with an addiction process particularly supporting incentive motivation theories. We have shown that activity in this salience network is then enhanced following exposure to highly salient or preferred sexually explicit cues [Brand et al., 2016; Seok and Sohn, 2015; Voon et al., 2014] along with enhanced attentional bias [Mechelmans et al., 2014] and desire specific to the sexual cue but not generalized sexual desire [Brand et al., 2016; Voon et al., 2014].

Enhanced attention to sexually explicit cues is further associated with preference for sexually conditioned cues thus confirming the relationship between sexual cue conditioning and attentional bias [Banca et al., 2016]. These findings of enhanced activity related to sexually conditioned cues differ from that of the outcome (or the unconditioned stimulus) in which enhanced habituation, possibly consistent with the concept of tolerance, increases the preference for novel sexual stimuli [Banca et al., 2016]. Together these findings help elucidate the underlying neurobiology of CSB leading toward a greater understanding of the disorder and identification of possible therapeutic markers.

25) Ventral Striatum Activity When Watching Preferred Pornographic Pictures is Correlated With Symptoms of Internet Pornography Addiction (Brand et al., 2016) – [greater cue reactivity/sensitization] – A German fMRI study. Finding #1: Reward center activity (ventral striatum) was higher for preferred pornographic pictures. Finding #2: Ventral striatum reactivity correlated with the internet sex addiction score. Both findings indicate sensitization and align with the addiction model. The authors state that the “Neural basis of Internet pornography addiction is comparable to other addictions.” An excerpt:

One type of Internet addiction is excessive pornography consumption, also referred to as cybersex or Internet pornography addiction. Neuroimaging studies found ventral striatum activity when participants watched explicit sexual stimuli compared to non-explicit sexual/erotic material. We now hypothesized that the ventral striatum should respond to preferred pornographic compared to non-preferred pornographic pictures and that the ventral striatum activity in this contrast should be correlated with subjective symptoms of Internet pornography addiction. We studied 19 heterosexual male participants with a picture paradigm including preferred and non-preferred pornographic material.

Pictures from the preferred category were rated as more arousing, less unpleasant, and closer to ideal. Ventral striatum response was stronger for the preferred condition compared to non-preferred pictures. Ventral striatum activity in this contrast was correlated with the self-reported symptoms of Internet pornography addiction. The subjective symptom severity was also the only significant predictor in a regression analysis with ventral striatum response as dependent variable and subjective symptoms of Internet pornography addiction, general sexual excitability, hypersexual behavior, depression, interpersonal sensitivity, and sexual behavior in the last days as predictors. The results support the role for the ventral striatum in processing reward anticipation and gratification linked to subjectively preferred pornographic material. Mechanisms for reward anticipation in ventral striatum may contribute to a neural explanation of why individuals with certain preferences and sexual fantasies are at-risk for losing their control over Internet pornography consumption.

26) Altered Appetitive Conditioning and Neural Connectivity in Subjects With Compulsive Sexual Behavior (Klucken et al., 2016) – [greater cue reactivity/sensitization and dysfunctional prefrontal circuits] – This German fMRI study replicated two major findings from Voon et al., 2014 and Kuhn & Gallinat 2014. Main Findings: The neural correlates of appetitive conditioning and neural connectivity were altered in the CSB group. According to the researchers, the first alteration – heightened amygdala activation – might reflect facilitated conditioning (greater “wiring” to previously neutral cues predicting porn images). The second alteration – decreased connectivity between the ventral striatum and the prefrontal cortex – could be a marker for impaired ability to control impulses.

Said the researchers, “These [alterations] are in line with other studies investigating the neural correlates of addiction disorders and impulse control deficits.” The findings of greater amygdalar activation to cues (sensitization) and decreased connectivity between the reward center and the prefrontal cortex (hypofrontality) are two of the major brain changes seen in substance addiction. In addition, 3 of the 20 compulsive porn users suffered from “orgasmic-erection disorder.” An excerpt:

In general, the observed increased amygdala activity and the concurrently decreased ventral striatal-PFC coupling allows speculations about the etiology and treatment of CSB. Subjects with CSB seemed more prone to establish associations between formally neutral cues and sexually relevant environmental stimuli. Thus, these subjects are more likely to encounter cues that elicit approaching behavior. Whether this leads to CSB or is a result of CSB must be answered by future research. In addition, impaired regulation processes, which are reflected in the decreased ventral striatal-prefrontal coupling, might further support the maintenance of the problematic behavior.

27) Compulsivity Across the Pathological Misuse of Drug and Non-Drug Rewards (Banca et al., 2016) – [greater cue reactivity/sensitization, enhanced conditioned responses] – This Cambridge University fMRI study compares aspects of compulsivity in alcoholics, binge-eaters, video game addicts and porn addicts (CSB). Excerpts:

In contrast to other disorders, CSB compared to HV showed faster acquisition to reward outcomes along with a greater perseveration in the reward condition irrespective of outcome. The CSB subjects did not show any specific impairments in set shifting or reversal learning. These findings converge with our previous findings of enhanced preference for stimuli conditioned to either sexual or monetary outcomes, overall suggesting enhanced sensitivity to rewards (Banca et al., 2016). Further studies using salient rewards are indicated.

28) Subjective Craving for Pornography and Associative Learning Predict Tendencies Towards Cybersex Addiction in a Sample of Regular Cybersex Users (Snagkowski et al., 2016) – [greater cue reactivity/sensitization, enhanced conditioned responses] – This unique study conditioned subjects to formerly neutral shapes, which predicted the appearance of a pornographic image. Excerpts:

There is no consensus regarding the diagnostic criteria of cybersex addiction. Some approaches postulate similarities to substance dependencies, for which associative learning is a crucial mechanism. In this study, 86 heterosexual males completed a Standard Pavlovian to Instrumental Transfer Task modified with pornographic pictures to investigate associative learning in cybersex addiction. Additionally, subjective craving due to watching pornographic pictures and tendencies towards cybersex addiction were assessed. Results showed an effect of subjective craving on tendencies towards cybersex addiction, moderated by associative learning.

Overall, these findings point towards a crucial role of associative learning for the development of cybersex addiction, while providing further empirical evidence for similarities between substance dependencies and cybersex addiction. In summary, the results of the current study suggest that associative learning might play a crucial role regarding the development of cybersex addiction. Our findings provide further evidence for similarities between cybersex addiction and substance dependencies since influences of subjective craving and associative learning were shown.

29) Mood changes after watching pornography on the Internet are linked to symptoms of Internet-pornography-viewing disorder (Laier & Brand, 2016) – [greater cravings/sensitization, less liking] – Excerpts:

The main results of the study are that tendencies towards Internet Pornography Disorder (IPD) were associated negatively with feeling generally good, awake, and calm as well as positively with perceived stress in daily life and the motivation to use Internet pornography in terms of excitation seeking and emotional avoidance.   Furthermore, tendencies towards IPD were negatively related to mood before and after watching Internet pornography as well as an actual increase of good and calm mood.

The relationship between tendencies towards IPD and excitement seeking due to Internet-pornography use was moderated by the evaluation of the experienced orgasm’s satisfaction. Generally, the results of the study are in line with the hypothesis that IPD is linked to the motivation to find sexual gratification and to avoid or to cope with aversive emotions as well as with the assumption that mood changes following pornography consumption are linked to IPD (Cooper et al., 1999 and Laier and Brand, 2014).

30) Problematic sexual behavior in young adults: Associations across clinical, behavioral, and neurocognitive variables (2016) – [poorer executive functioning] – Individuals with Problematic Sexual Behaviors (PSB) exhibited several neuro-cognitive deficits. These findings indicate poorer executive functioning (hypofrontality) which is a key brain feature occurring in drug addicts. A few excerpts:

One notable result from this analysis is that PSB shows significant associations with a number of deleterious clinical factors, including lower self-esteem, decreased quality of life, elevated BMI, and higher comorbidity rates for several disorders…

…it is also possible that the clinical features identified in the PSB group are actually the result of a tertiary variable which gives rise to both PSB and the other clinical features. One potential factor filling this role could be the neurocognitive deficits identified in the PSB group, particularly those relating to working memory, impulsivity/impulse control, and decision making. From this characterization, it is be possible to trace the problems evident in PSB and additional clinical features, such as emotional dysregulation, to particular cognitive deficits…

If the cognitive problems identified in this analysis are actually the core feature of PSB, this may have notable clinical implications.

31) Methylation of HPA Axis Related Genes in Men With Hypersexual Disorder (Jokinen et al., 2017) – [dysfunctional stress response, epigenetic changes] – This is a follow-up of #16 above which found that sex addicts have dysfunctional stress systems – a key neuro-endocrine change caused by addiction. The current study found epigenetic changes on genes central to the human stress response and closely associated with addiction. With epigenetic changes, the DNA sequence isn’t altered (as happens with a mutation). Instead, the gene is tagged and its expression is turned up or down (short video explaining epigenetics). The epigenetic changes reported in this study resulted in altered CRF gene activity. CRF is a neurotransmitter and hormone that drives addictive behaviors such as cravings, and is a major player in many of the withdrawal symptoms experienced in connection with substance and behavioral addictions, including porn addiction.

32) Exploring the Relationship between Sexual Compulsivity and Attentional Bias to Sex-Related Words in a Cohort of Sexually Active Individuals (Albery et al., 2017) – [greater cue reactivity/sensitization, desensitization] – This study replicates the findings of this 2014 Cambridge University study, which compared the attentional bias of porn addicts to healthy controls. Here’s what’s new: The study correlated the “years of sexual activity” with 1) the sex addiction scores and also 2) the results of the attentional bias task.

Among those scoring high on sexual addiction, fewer years of sexual experience were related to greater attentional bias (explanation of attentional bias). So higher sexual compulsivity scores + fewer years of sexual experience = greater signs of addiction (greater attentional bias, or interference). But attentional bias declines sharply in the compulsive users, and disappears at the highest number of years of sexual experience. The authors concluded that this result could indicate that more years of “compulsive sexual activity” lead to greater habituation or a general numbing of the pleasure response (desensitization). An excerpt from the conclusion:

One possible explanation for these results is that as a sexually compulsive individual engages in more compulsive behaviour, an associated arousal template develops [36–38] and that over time, more extreme behaviour is required for the same level of arousal to be realised. It is further argued that as an individual engages in more compulsive behaviour, neuropathways become desensitized to more ‘normalised’ sexual stimuli or images and individuals turn to more ‘extreme’ stimuli to realise the arousal desired. This is in accordance with work showing that ‘healthy’ males become habituated to explicit stimuli over time and that this habituation is characterised by decreased arousal and appetitive responses [39].

This suggests that more compulsive, sexually active participants have become ‘numb’ or more indifferent to the ‘normalised’ sex-related words used in the present study and as such display decreased attentional bias, while those with increased compulsivity and less experience still showed interference because the stimuli reflect more sensitised cognition.

33) Executive Functioning of Sexually Compulsive and Non-Sexually Compulsive Men Before and After Watching an Erotic Video (Messina et al., 2017) – [poorer executive functioning, greater cravings/sensitization] – Exposure to porn affected executive functioning in men with “compulsive sexual behaviors,” but not healthy controls. Poorer executive functioning when exposed to addiction-related cues is a hallmark of substance disorders (indicating both altered prefrontal circuits and sensitization). Excerpts:

This finding indicates better cognitive flexibility after sexual stimulation by controls compared with sexually compulsive participants. These data support the idea that sexually compulsive men do not to take advantage of the possible learning effect from experience, which could result in better behavior modification. This also could be understood as a lack of a learning effect by the sexually compulsive group when they were sexually stimulated, similar to what happens in the cycle of sexual addiction, which starts with an increasing amount of sexual cognition, followed by the activation of sexual scripts and then orgasm, very often involving exposure to risky situations.

34) Can Pornography be Addictive? An fMRI Study of Men Seeking Treatment for Problematic Pornography Use (Gola et al., 2017) – [greater cue reactivity/sensitization, enhanced conditioned responses] – An fMRI study involving a unique cue-reactivity paradigm where formerly neutral shapes predicted the appearance of pornographic images. Excerpts:

Men with and without problematic porn use (PPU) differed in brain reactions to cues predicting erotic pictures, but not in reactions to erotic pictures themselves, consistent with the incentive salience theory of addictions. This brain activation was accompanied by increased behavioral motivation to view erotic images (higher ‘wanting’). Ventral striatal reactivity for cues predicting erotic pictures was significantly related to the severity of PPU, amount of pornography use per week and number of weekly masturbations. Our findings suggest that like in substance-use and gambling disorders the neural and behavioral mechanisms linked to anticipatory processing of cues relate importantly to clinically relevant features of PPU. These findings suggest that PPU may represent a behavioral addiction and that interventions helpful in targeting behavioral and substance addictions warrant consideration for adaptation and use in helping men with PPU.

35) Conscious and Non-Conscious Measures of Emotion: Do They Vary with Frequency of Pornography Use? (Kunaharan et al., 2017) – [habituation or desensitization] – Study assessed porn users’ responses (EEG readings & Startle Response) to various emotion-inducing images – including erotica. The study found several neurological differences between low frequency porn users and high frequency porn users. Excerpts:

Findings suggest that increased pornography use appears to have an influence on the brain’s non-conscious responses to emotion-inducing stimuli which was not shown by explicit self-report.

4.1. Explicit Ratings: Interestingly, the high porn use group rated the erotic images as more unpleasant than the medium use group. The authors suggest this may be due to the relatively “soft-core” nature of the “erotic” images contained in the IAPS database not providing the level of stimulation that they may usually seek out, as it has been shown by Harper and Hodgins [58] that with frequent viewing of pornographic material, many individuals often escalate into viewing more intense material to maintain the same level of physiological arousal.

The “pleasant” emotion category saw valence ratings by all three groups to be relatively similar with the high use group rating the images as slightly more unpleasant on average than the other groups. This may again be due to the “pleasant” images presented not being stimulating enough for the individuals in the high use group. Studies have consistently shown a physiological downregulation in processing of appetitive content due to habituation effects in individuals who frequently seek out pornographic material [3, 7, 8]. It is the authors’ contention that this effect may account for the results observed.

4.3. Startle Reflex Modulation (SRM): The relative higher amplitude startle effect seen in the low and medium porn use groups may be explained by those in the group intentionally avoiding the use of pornography, as they may find it to be relatively more unpleasant. Alternatively, the results obtained also may be due to a habituation effect, whereby individuals in these groups do watch more pornography than they explicitly stated—possibly due to reasons of embarrassment among others, as habituation effects have been shown to increase startle eye blink responses [41, 42].

36) Exposure to Sexual Stimuli Induces Greater Discounting Leading to Increased Involvement in Cyber Delinquency Among Men (Cheng & Chiou, 2017) – [poorer executive functioning, greater impulsivity – causation experiment] – In two studies exposure to visual sexual stimuli resulted in: 1) greater delayed discounting (inability to delay gratification), 2) greater inclination to engage in cyber-delinquency, 3) greater inclination to purchase counterfeit goods and hack someone’s Facebook account. Taken together this indicates that porn use increases impulsivity and may reduce certain executive functions (self-control, judgment, foreseeing consequences, impulse control). Excerpt:

People frequently encounter sexual stimuli during Internet use. Research has shown that stimuli inducing sexual motivation can lead to greater impulsivity in men, as manifested in greater temporal discounting (i.e., a tendency to prefer smaller, immediate gains to larger, future ones).

In conclusion, the current results demonstrate an association between sexual stimuli (e.g., exposure to pictures of sexy women or sexually arousing clothing) and men’s involvement in cyber delinquency. Our findings suggest that men’s impulsivity and self-control, as manifested by temporal discounting, are susceptible to failure in the face of ubiquitous sexual stimuli. Men may benefit from monitoring whether exposure to sexual stimuli is associated with their subsequent delinquent choices and behavior. Our findings suggest that encountering sexual stimuli can tempt men down the road of cyber delinquency

The current results suggest that the high availability of sexual stimuli in cyberspace may be more closely associated with men’s cyber-delinquent behavior than previously thought.

37) Predictors for (Problematic) Use of Internet Sexually Explicit Material: Role of Trait Sexual Motivation and Implicit Approach Tendencies Towards Sexually Explicit Material (Stark et al., 2017) – [greater cue reactivity/sensitization/cravings] – Excerpts:

The present study investigated whether trait sexual motivation and implicit approach tendencies toward sexual material are predictors of problematic SEM use and of the daily time spent watching SEM. In a behavioral experiment, we used the Approach-Avoidance Task (AAT) for measuring implicit approach tendencies towards sexual material. A positive correlation between implicit approach tendency towards SEM and the daily time spent on watching SEM might be explained by attentional effects: A high implicit approach tendency can be interpreted as an attentional bias towards SEM. A subject with this attentional bias might be more attracted to sexual cues on the Internet resulting in higher amounts of time spent on SEM sites.

38) Pornography Addiction Detection based on Neurophysiological Computational Approach (Kamaruddin et al., 2018) – Excerpt:

In this paper, a method of using brain signal from frontal area captured using EEG is proposed to detect whether the participant may have porn addiction or otherwise. It acts as a complementary approach to common psychological questionnaire. Experimental results show that the addicted participants had low alpha waves activity in the frontal brain region compared to non-addicted participants. It can be observed using power spectra computed using Low Resolution Electromagnetic Tomography (LORETA). The theta band also show there is disparity between addicted and non-addicted. However, the distinction is not as obvious as alpha band.

39) Gray matter deficits and altered resting-state connectivity in the superior temporal gyrus among individuals with problematic hypersexual behavior (Seok & Sohn, 2018) – [gray matter deficits in temporal cortex, poorer functional connectivity between temporal cortex and precuneus & caudate] – An fMRI study comparing carefully screened sex addicts (“problematic hypersexual behavior”) to healthy control subjects. Compared to controls sex addicts had: 1) reduced gray matter in the temporal lobes (regions associated with inhibiting sexual impulses); 2) reduced precuneus to temporal cortex functional connectivity (may indicate abnormality in ability to shift attention); 3) reduced caudate to temporal cortex functional connectivity (may inhibit the top-down control of impulses). Excerpts:

These findings suggest that the structural deficits in the temporal gyrus and the altered functional connectivity between the temporal gyrus and specific areas (i.e., the precuneus and caudate) might contribute to the disturbances in tonic inhibition of sexual arousal in individuals with PHB. Thus, these results suggest that changes in structure and functional connectivity in the temporal gyrus might be PHB specific features and may be biomarker candidates for the diagnosis of PHB.

Gray matter enlargement in the right cerebellar tonsil and increased connectivity of the left cerebellar tonsil with the left STG were also observed…. Therefore, it is possible that the increased gray matter volume and functional connectivity in the cerebellum is associated with compulsive behavior in individuals with PHB.

In summary, the present VBM and functional connectivity study showed gray matter deficits and altered functional connectivity in the temporal gyrus among individuals with PHB. More importantly, the diminished structure and functional connectivity were negatively correlated with the severity of PHB. These findings provide new insights into the underlying neural mechanisms of PHB.

40) Tendencies toward Internet-pornography-use disorder: Differences in men and women regarding attentional biases to pornographic stimuli (Pekal et al., 2018) – [greater cue reactivity/sensitization, enhanced cravings]. Excerpts:

 Several authors consider Internet-pornography-use disorder (IPD) as addictive disorder. One of the mechanisms that has been intensively studied in substance- and non-substance-use disorders is an enhanced attentional bias toward addiction-related cues. Attentional biases are described as cognitive processes of individual’s perception affected by the addiction-related cues caused by the conditioned incentive salience of the cue itself. It is assumed in the I-PACE model that in individuals prone to develop IPD symptoms implicit cognitions as well as cue-reactivity and craving arise and increase within the addiction process. To investigate the role of attentional biases in the development of IPD, we investigated a sample of 174 male and female participants. Attentional bias was measured with the Visual Probe Task, in which participants had to react on arrows appearing after pornographic or neutral pictures.

In addition, participants had to indicate their sexual arousal induced by pornographic pictures. Furthermore, tendencies toward IPD were measured using the short-Internetsex Addiction Test. The results of this study showed a relationship between attentional bias and symptom severity of IPD partially mediated by indicators for cue-reactivity and craving. While men and women generally differ in reaction times due to pornographic pictures, a moderated regression analysis revealed that attentional biases occur independently of sex in the context of IPD symptoms. The results support theoretical assumptions of the I-PACE model regarding the incentive salience of addiction-related cues and are consistent with studies addressing cue-reactivity and craving in substance-use disorders.

41) Altered Prefrontal and Inferior Parietal Activity During a Stroop Task in Individuals With Problematic Hypersexual Behavior (Seok & Sohn, 2018) – [poorer executive control- impaired PFC functionality]. Excerpts:

Accumulating evidence suggests a relationship between problematic hypersexual behavior (PHB) and diminished executive control. Clinical studies have demonstrated that individuals with PHB exhibit high levels of impulsivity; however, relatively little is known regarding the neural mechanisms underlying impaired executive control in PHB. This study investigated the neural correlates of executive control in individuals with PHB and healthy controls using event-related functional magnetic resonance imaging (fMRI).

Twenty-three individuals with PHB and 22 healthy control participants underwent fMRI while performing a Stroop task. Response time and error rates were measured as surrogate indicators of executive control. Individuals with PHB exhibited impaired task performance and lower activation in the right dorsolateral prefrontal cortex (DLPFC) and inferior parietal cortex relative to healthy controls during the Stroop task. In addition, blood oxygen level-dependent responses in these areas were negatively associated with PHB severity. The right DLPFC and inferior parietal cortex are associated with higher-order cognitive control and visual attention, respectively. Our findings suggest that individuals with PHB have diminished executive control and impaired functionality in the right DLPFC and inferior parietal cortex, providing a neural basis for PHB.

42) Trait and state impulsivity in males with tendency towards Internet-pornography-use disorder (Antons & Brand, 2018) – [enhanced cravings, greater state & trait impulsivity]. Excerpts:

Results indicate that trait impulsivity was associated with higher symptom severity of Internet-pornography-use disorder (IPD). Especially those males with higher trait impulsivity and state impulsivity in the pornographic condition of the stop-signal task as well as those with high craving reactions showed severe symptoms of IPD.

The results indicate that both trait and state impulsivity play a crucial role in the development of IPD. In accordance with dual-process models of addiction, the results may be indicative of an imbalance between the impulsive and reflective systems which might be triggered by pornographic material. This may result in loss of control over the Internet-pornography use albeit experiencing negative consequences.

43) Facets of impulsivity and related aspects differentiate among recreational and unregulated use of Internet pornography (Stephanie et al., 2019) – [enhanced cravings, greater delayed discounting (hypofrontality), habituation]. Excerpts:

Because of its primarily rewarding nature, Internet pornography (IP) is a predestinated target for addictive behaviors. Impulsivity-related constructs have been identified as promoters of addictive behaviors. In this study, we investigated impulsive tendencies (trait impulsivity, delay discounting, and cognitive style), craving toward IP, attitude regarding IP, and coping styles in individuals with recreational–occasional, recreational–frequent, and unregulated IP use. Groups of individuals with recreational–occasional use (n = 333), recreational–frequent use (n = 394), and unregulated use (n = 225) of IP were identified by screening instruments.

Individuals with unregulated use showed the highest scores for craving, attentional impulsivity, delay discounting, and dysfunctional coping, and lowest scores for functional coping and need for cognition. The results indicate that some facets of impulsivity and related factors such as craving and a more negative attitude are specific for unregulated IP users. The results are also consistent with models on specific Internet use disorders and addictive behaviors….

Furthermore, individuals with unregulated IP use had a more negative attitude toward IP compared to the recreational–frequent users. This result might suggest that individuals with unregulated IP use have a high motivation or urge to use IP, although they may have developed a negative attitude toward IP use, perhaps because they have already experienced negative consequences linked to their IP use pattern. This is consistent with the incentive-sensitization theory of addiction (Berridge & Robinson, 2016), which proposes a shift from liking to wanting during addiction.

A further interesting result is that the effect size for post-hoc tests duration in minutes per session, when comparing unregulated users with recreational–frequent users, was higher in comparison to the frequency per week. This might indicate that individuals with unregulated IP use especially have difficulties to stop watching IP during a session or need longer time to achieve the desired reward, which might be comparable with a form of tolerance in substance use disorders. This is consistent with the results from a diary assessment, which revealed that pornographic binges are one of the most characteristic behaviors in treatment-seeking males with compulsive sexual behaviors (Wordecha et al., 2018).

44) Approach bias for erotic stimuli in heterosexual male college students who use pornography (Skyler et al., 2019) – [enhanced approach bias (sensitization)]. Excerpts:

The results support the hypothesis that heterosexual male college students who use pornography are faster to approach than to avoid erotic stimuli during an AAT task….. These findings are also in line with several SRC tasks suggesting that addicted individuals display an action tendency to approach rather than avoid addictive stimuli (Bradley et al., 2004; Field et al., 2006, 2008).

Overall, the findings suggest that approach for addictive stimuli may be a more rapid or prepared response than avoidance, which may be explained by the interplay of other cognitive biases in addictive behaviors….. Moreover, total scores on the BPS were positively correlated with approach bias scores, indicating that the greater the severity of problematic pornography use, the stronger the degree of approach for erotic stimuli. This association was further supported by results suggesting that individuals with problematic pornography use, as classified by the PPUS, showed more than a 200% stronger approach bias for erotic stimuli compared to individuals without problematic pornography use.

Taken together, the results suggest parallels between substance and behavioral addictions (Grant et al., 2010). Pornography use (particularly problematic use) was linked to faster approaches to erotic stimuli than neutral stimuli, an approach bias similar to that observed in alcohol-use disorders (Field et al., 2008; Wiers et al., 2011), cannabis use (Cousijn et al., 2011; Field et al., 2006), and tobacco-use disorders (Bradley et al., 2004). An overlap between cognitive features and neurobiological mechanisms involved in both substance addictions and problematic pornography use seems likely, which is consistent with prior studies (Kowalewska et al., 2018; Stark et al., 2018).

45) Hypermethylation-associated downregulation of microRNA-4456 in hypersexual disorder with putative influence on oxytocin signalling: A DNA methylation analysis of miRNA genes (Bostrom et al., 2019) – [likely dysfunctional stress system]. Study on subjects with hypersexuality (porn/sex addiction) reports epigenetic changes mirroring those occurring in alcoholics. The epigenetic changes occurred in genes associated with the oxytocin system (which is important in love, bonding, addiction, stress, sexual functioning, etc.). Excerpts:

In a DNA methylation association analysis in peripheral blood, we identify distinct CpG-sites associated with MIR708 and MIR4456 that are significantly differentially methylated in hypersexuality disorder (HD) patients. Additionally, we demonstrate that hsamiR- 4456 associated methylation locus cg01299774 is differentially methylated in alcohol dependence, suggesting that it may be primarily associated with the addictive component observed in HD.

The involvement of the oxytocin signaling pathway identified in this study appears to be significantly implicated in many of the characteristics defining HD as proposed by Kafka et al. [1], such as sexual desire dysregulation, compulsivity, impulsivity and (sexual) addiction.

In conclusion, MIR4456 has significantly lower expression in HD. Our study provides evidence that DNA methylation at the cg01299774 locus is associated with the expression of MIR4456. This miRNA putatively targets genes preferentially expressed in brain tissue and involved in major neuronal molecular mechanisms thought to be relevant to the pathogenesis of HD. Our findings from the investigation of shifts in the epigenome contributes to further elucidating the biological mechanisms behind the pathophysiology of HD with special emphasis onMIR4456 and its role in oxytocin regulation.

46) Gray matter volume differences in impulse control and addictive disorders (Draps et al., 2020) –  [hypofrontaility: descreased prefrontal cortex & anterior cingulate cortex  gray matter]. Excerpts:

Here we contrast gray matter volumes (GMVs) across groups of individuals with compulsive sexual behavior disorder (CSBD), gambling disorder (GD), and alcohol use disorder (AUD) with those with none of these disorders (healthy controls participants; HCs).

Affected individuals (CSBD, GD, AUD) compared to HC participants showed smaller GMVs in the left frontal pole, specifically in the orbitofrontal cortex. The most pronounced differences were observed in the GD and AUD groups, and the least in the CSBD group. There was a negative correlation between GMVs and disorder severity in the CSBD group. Higher severity of CSBD symptoms was correlated with decreased GMV in the right anterior cingulate gyrus.

This study is the first showing smaller GMVs in 3 clinical groups of CSBD, GD and AUD. Our findings suggest similarities between specific impulse control disorders and addictions.

The anterior cingulate cortex (ACC) has been implicated functionally in cognitive control, processing negative stimuli [56],[57], error prediction processing, reward learning [58], [59] and cue-reactivity [60],[34]. With respect to CSBD, ACC activity in response to sexually explicit cues was linked to sexual desire in men with CSBD [61]. Men with CSBD also displayed an enhanced preference for sexual novelty, which was related to ACC habituation [62]. As such, the current findings extend prior functional studies by suggesting that ACC volume relates importantly to CSBD symptomatology in men.

47) High Plasma Oxytocin Levels in Men With Hypersexual Disorder (Jokinen et al., 2020) [dysfunctional stress response].– From the research group that published 4 previous neuro-endocrine studies on male “hypersexuals” (sex/porn addicts). Because oxytocin is involved in our stress response, higher blood levels were interpreted as an indicator of an overactive stress system in the sex addicts. This finding aligns with the researcher’s previous studies and neurological studies reporting a dysfunctional stress response in substance abusers. Interestingly, therapy (CBT) reduced oxytocin levels in hypersexual patients. Excerpts:

Hypersexual disorder (HD) integrating pathophysiological aspects such as sexual desire deregulation, sexual addiction, impulsivity and compulsivity was suggested as a diagnosis for the DSM-5. “Compulsive Sexual Behavior Disorder” is now presented as an impulse-control disorder in ICD-11. Recent studies showed dysregulated HPA axis in men with HD. Oxytocin (OXT) affects the function of the HPA axis; no studies have assessed OXT levels in patients with HD. Whether a CBT treatment for HD symptoms has an effect on OXT levels has not been investigated.

We examined plasma OXT levels in 64 male patients with HD and 38 male age-matched healthy volunteers. Further, we examined correlations between plasma OXT levels and dimensional symptoms of HD using the rating scales measuring hypersexual behaviour.

Patients with HD had significantly higher OXT  levels compared to healthy volunteers. There were significant positive correlations between OXT levels and the rating scales measuring hypersexual behaviour. Patients who completed CBT treatment had significant reduction of OXT levels from pre-treatment. The results suggest hyperactive oxytonergic system in male patients with hypersexual disorder which may be a compensatory mechanism to attenuate hyperactive stress system. A successful CBT group therapy may have effect on hyperactive oxytonergic system.

48) Inhibitory control and problematic Internet-pornography use – The important balancing role of the insula (Anton & Brand, 2020) – [tolerance or habituation] – The authors state their results indicate tolerance, a hallmark of an addiction process. Excerpts:

Our current study should be seen as a first approach inspiring future investigations regarding the associations between psychological and neural mechanisms of craving, problematic IP use, motivation to change behavior, and inhibitory control.

Consistent with previous studies (e.g., Antons & Brand, 2018; Brand, Snagowski, Laier, & Maderwald, 2016; Gola et al., 2017; Laier et al., 2013), we found a high correlation between subjective craving and symptom severity of problematic IP use in both conditions. However, the increase in craving as measure for cue-reactivity was not associated with symptom severity of problematic IP use, this may relate to tolerance (cf. Wéry & Billieux, 2017) given that the pornographic images used in this study were not individualized in terms of subjective preferences. Therefore, the standardized pornographic material used may not be strong enough for inducing cue-reactivity in individuals with high symptom severity associated with low effects on the impulsive, reflective, and interoceptive systems as well as inhibitory control ability.

Effects of tolerance and motivational aspects may explain the better inhibitory control performance in individuals with higher symptom severity which was associated with differential activity of the interoceptive and reflective system. Diminished control over IP use presumably results from the interaction between the impulsive, reflective, and interoceptive systems.

Taken together, the insula as the key structure representing the interoceptive system plays a pivotal role in inhibitory control when pornographic images are present. Data suggest that individuals with higher symptom severity of problematic IP use performed better in the task due to decreased insula activity during image processing and increased activity during inhibitory control processing. This pattern of activity might be based on effects of tolerance, that is, less hyperactivity of the impulsive system causes less controlling resources of the interoceptive and reflective system. 

Hence, a shift from impulsive to compulsive behaviors as a consequence of developing problematic IP use or a motivational (avoidance-related) aspect might be relevant, so that all resources were focused on the task and away from pornographic images. The study contributes to a better understanding of diminished control over IP use which is presumably not only a result of an imbalance between dual systems but of the interaction between impulsive, reflective, and interoceptive systems.

49) Normal Testosterone but Higher Luteinizing Hormone Plasma Levels in Men With Hypersexual Disorder (2020) – [could indicate dysfunctional stress response] – From the research group that published 5 previous neuro-endocrine studies on male “hypersexuals” (sex/porn addicts), revealing altered stress systems, a major marker for addiction (1, 2, 3, 4, 5.). Excerpts:

In this study, we found that male patients with HD had no significant difference in plasma testosterone levels compared with healthy volunteers. On the contrary, they had significantly higher plasma levels of LH.

HD includes in its definition that the behavior can be a result of dysphoric states and stress,¹ and we have previously reported a dysregulation with hyperactivity of the HPA axis¹³ as well as related epigenetic changes in men with HD.

There are complex interactions between HPA and HPG axis, both excitatory as well as inhibitory with differences depending on the developmental stage of the brain.²⁷ Stressful events through effects of the HPA axis may cause an inhibition of LH suppression and consequently of reproduction.²⁷ The 2 systems have reciprocal interactions, and early stressors may alter neuroendocrine responses through epigenetic modifications.

The proposed mechanisms might include the HPA and HPG interaction, the reward neural network, or the inhibition of regulation impulse control of prefrontal cortex regions.³² In conclusion, we report for the first time increased LH plasma levels in hypersexual men compared with healthy volunteers. These preliminary findings contribute to growing literature on the involvement of neuroendocrine systems and dysregulation in HD.

50) Approach bias for erotic stimuli among heterosexual female college students who use pornography (2020) [sensitization and desensitization] – Neuro-psychological study on female porn users reports findings that mirror those seen in substance addiction studies. Approach bias to porn (sensitization) and anhedonia (desensitization) were positively correlated with pornography use. Study also reported: “we also found a significant positive association between erotic approach bias scores and scores on the SHAPS, which quantifies anhedonia. This indicates that the stronger the approach bias for erotic stimuli, the less pleasure the individual reported experiencing“. Put simply, the neuropsychological sign of an addiction process correlated with lack of pleasure (anhedonia). Excerpts:

Approach bias, or the relatively automatic action tendency to move certain stimuli toward the body rather than away from it, is a key cognitive process involved in key cognitive process involved in addictive behaviors. Dual processing models of addiction posit that addictive behaviors develop as a result of an imbalance between appetitive, “impulsive” motivational
drives and regulatory executive systems. Repeated engagement in addictive behaviors may lead to relatively automatic action tendencies whereby individuals approach rather than avoid addictive stimuli. This study assessed whether an approach bias for erotic stimuli exists among heterosexual college-aged females who report using pornography.

Participants demonstrated a significant approach bias of 24.81 ms for erotic stimuli as compared to neutral stimuli, and this approach bias significantly positively correlated with Problematic Pornography Use Scale scores. These findings are in line with and extend previous findings reporting an approach bias for erotic stimuli among men who regularly use pornography (Sklenarik et al., 2019; Stark et al., 2017).

Moreover, approach bias scores were significantly positively correlated with anhedonia  indicating that the stronger the degree of approach for erotic stimuli, the more anhedonia that was observed.…..This indicates that the stronger the approach bias for erotic stimuli, the less pleasure the individual reported experiencing.

51) Sexual cues alter working memory performance and brain processing in men with compulsive sexual behavior (2020) – [sensitization and poorer executive functioning] – Excerpts:

On the behavioural level, patients were slowed down by pornographic material depending on their pornography consumption in the last week, which was reflected by a higher activation in the lingual gyrus. In addition, the lingual gyrus showed a higher functional connectivity to the insula during processing of pornographic stimuli in the patient group. In contrast, healthy subjects showed faster responses when confronted with pornographic pictures only with high cognitive load. Also, patients showed a better memory for pornographic pictures in a surprise recognition task compared to controls, speaking for a higher relevance of pornographic material in the patient group. These findings are in line with the incentive salience theory of addiction, especially the higher functional connectivity to the salience network with the insula as a key hub and the higher lingual activity during processing of pornographic pictures depending on recent pornography consumption.

…. This could be interpreted in a way that pornographic material has (probably due to learning processes) a high relevance for patients and thus activates the salience (insula) and attention network (inferior parietal), which then leads to a slower reaction time as the salient information is not relevant for the task. Based on these findings, one may conclude that, for subjects displaying CSB, pornographic material has a higher distracting effect and thus a higher salience. Subsequently, the data supports the IST of addiction in CSB.

52) Subjective reward value of visual sexual stimuli is coded in human striatum and orbitofrontal cortex (2020) – [sensitization] – Excerpts:

The higher a subject rated a VSS clip on sexual arousal or valence, the higher activity we found in NAcc, caudate nucleus and OFC during VSS viewing. Additionally, the association between individual sexual arousal ratings and NAcc as well as caudate nucleus activity was stronger when subjects reported more symptoms of problematic pornography use (PPU) measured by the s-IATsex

These individual differences in preference coding might represent a mechanism that mediates addictive VSS use experienced by some individuals. We not only found an association of NAcc and caudate activity with sexual arousal ratings during VSS viewing but the strength of this association was greater when the subject reported more problematic pornography use (PPU). The result supports the hypothesis, that incentive value responses in NAcc and caudate differentiate more strongly between differently preferred stimuli, the more a subject experiences PPU. This extends past studies, where PPU has been linked to a higher striatal response to VSS as compared to a control or non-preferred condition [29,38]. One study, also using an SID task, found increased NAcc activity associated with increased PPU during the anticipation phase only [41]. Our results indicate that a similar effect, i.e. altered incentive salience processing associated with PPU, can also be found in the delivery phase, but only if individual preference is taken into account. The increasing differentiation of incentive value signals in the NAcc could reflect an increased need for seeking and identifying preferred VSS during addiction development.

Given these results can be replicated, they may have important clinical implications. Increased differentiation of incentive value signals might be connected to an increase in time spent searching for highly stimulating material, which later leads to issues in personal or professional life and suffering because of this behavior.

53) The Neurosciences of Health Communication: An fNIRS Analysis of Prefrontal Cortex and Porn Consumption in Young Women for the Development of Prevention Health Programs (2020) – Excerpts:

The results indicate that the viewing of the pornographic clip (vs. control clip) causes an activation of Brodmann’s area 45 of the right hemisphere. An effect also appears between the level of self-reported consumption and the activation of right BA 45: the higher the level of self-reported consumption, the greater the activation. On the other hand, those participants who have never consumed pornographic material do not show activity of the right BA 45 compared to the control clip (indicating a qualitative difference between non-consumers and consumers). These results are consistent with other research made in the field of addictions. It is hypothesized that the mirror neuron system may be involved, through the mechanism of empathy, which could provoke vicarious eroticism.

54) Event-related potentials in a two-choice oddball task of impaired behavioral inhibitory control among males with tendencies towards cybersex addiction (2020) – Excerpts:

Impaired behavioral inhibitory control (BIC) is known to play a crucial role in addictive behavior. However, research has been inconclusive as to whether this is also the case for cybersex addiction. This study aimed to investigate the time course of BIC in male individuals with tendencies towards cybersex addiction (TCA) using event-related potentials (ERPs) and to provide neurophysiological evidence of their deficient BIC.

Individuals with TCA were more impulsive than HC participants and shared neuropsychological and ERP characteristics of substance use disorder or behavioral addictions, which supports the view that cybersex addiction can be conceptualized as a behavioral addiction.

Theoretically, our results indicate that cybersex addiction resembles substance use disorder and impulse control disorder in terms of impulsivity at electrophysiological and behavioral levels. Our findings may fuel the persistent controversy about the possibility of cybersex addiction as a novel type of psychiatric disorder.

55) White matter microstructural and Compulsive Sexual Behaviors Disorder – Diffusion Tensor Imaging study – Brain scan study comparing the white matter structure of porn/sex addicts (CSBD) to controls. Significant differences between controls and CSB subjects. Excerpts: 

This is one of the first DTI studies assessing differences between patients with the Compulsive Sexual Behaviors Disorder and healthy controls. Our analysis has uncovered FA reductions in six regions of the brain in CSBD subjects, compared to controls. The differentiating tracts were found in the cerebellum (there were probably parts of the same tract in the cerebellum), the retrolenticular part of the internal capsule, the superior corona radiata and the middle or lateral occipital gyrus white matter.

Our DTI data shows that the neural correlates of CSBD overlap with regions previously reported in the literature as related both, to addiction and OCD (see the red area in Fig. 3). Thus, the present study demonstrated an important similarity in shared FA reductions between CSBD and both OCD and addictions.

56) Sexual incentive delay in the scanner: Sexual cue and reward processing, and links to problematic porn consumption and sexual motivation – The findings do not align with the addiction model (cue-reactivity).

57) Aberrant orbitofrontal cortex reactivity to erotic cues in Compulsive Sexual Behavior Disorder (2021)– [sensitization – greater cue-reactivity in the ventral striatum and anterior orbitofrontal cortex in porn addicts compared to healthy controls] Excerpts:

The functional pattern observed in CSBD subjects comprising superior parietal cortices, supramarginal gyrus, pre and postcentral gyrus, and basal ganglia might be indicative of intensified (as compared to healthy controls) attentional, somatosensory, and motor preparation to erotic reward approach and consummation (wanting) in CSBD which is evoked by predictive cues (Locke & Braver, 2008; Hirose, Nambu, & Naito, 2018). This is in line with Incentive Sensitization theory of addiction (Robinson & Berridge, 2008) and existing data on cue-reactivity in addictive behaviors (Gola & Draps, 2018; Gola, Wordecha, et al., 2017; Kowalewska et al., 2018; Kraus et al., 2016b; Potenza et al., 2017; Stark, Klucken, Potenza, Brand, & Strahler, 2018; Voon et al., 2014)….

Most importantly, with the results of ROI analysis, this work broadens the previously-published results (Gola, Wordecha, et al., 2017) by showing that the elevated response of reward circuitry to erotic reward cues in CSBD occurs not only in the ventral striatum in the reward anticipation phase but also in the anterior orbitofrontal cortex (aOFC). Additionally, the activity in this region also seems to be dependent on reward probability. The BOLD signal change was higher in CSBD individuals than in healthy controls, particularly for the lower probability values, which might indicate that lower chances of obtaining the erotic reward do not decrease the excessive behavioral motivation induced by the presence of the erotic reward cues.

Based on our data, it might be suggested that the aOFC plays an important role in mediating the specific ability of cues of particular reward types to motivate reward-seeking behavior in CSBD participants. In fact, the role of OFC has been implicated in neuroscientific models of addictive behaviors.

58) Electrophysiological evidence of enhanced early attentional bias toward sexual images in individuals with tendencies toward cybersex addiction (2021) [sensitization/cue reactivity and habituation/desensitization] Study assessed porn addicts’ behavior (response times) and brain responses (EEG) to pornographic and neutral images. In line with Mechelmans et al. (2014) above, this study found porn addicts have greater early attentional bias to sexual stimuli. What’s new is this study found neurophysiological evidence of this early attentional bias to addiction related cues. Excerpts:

Incentive sensitization theory has been employed to explain attentional bias toward addiction-related cues in individuals with certain addiction disorders (Field & Cox, 2008; Robinson & Berridge, 1993). This theory proposes that repeated substance use increases the dopaminergic response, making it more sensitive and motivationally salient. This triggers the characteristic behavior of addicted individuals through the urge to feel the experiences elicited in response to addiction-related cues (Robinson & Berridge, 1993). After the repeated experience of a given stimulus, related cues become salient and attractive, thus garnering attention. The findings of this study showed that [porn addicts] did in fact present stronger interference in the color judging of sexually explicit images relative to neutral ones. This evidence is similar to results reported for substance-related (Asmaro et al., 2014; Della Libera et al., 2019) and non-substance-related behavior, including sexual behavior (Pekal et al., 2018; Sklenarik, Potenza, Gola, Kor, Kraus, & Astur, 2019; Wegmann & Brand, 2020).

Our novel result is that individuals with [porn addiction] displayed the early modulation of P200 relative to neutral stimuli in response to sexual stimuli. This result is consistent with that of Mechelmans et al. (2014), who reported participants with compulsive sexual behavior showing greater attentional bias toward sexually explicit than neutral stimuli, especially during early stimuli latency (i.e., an early orienting attentional response). P200 is associated with lower processing of stimuli (Crowley & Colrain, 2004). Thus, our P200 findings demonstrate that the differences between sexual and neutral stimuli may be discriminated by individuals with [porn addiction] at relatively early stages of attention during the low-level processing of stimuli. Enhanced P200 amplitudes to sexual stimuli in the [porn addiction] group manifest as an amplified early attentional engagement because the salience of these stimuli increases. Other addiction ERP studies have revealed comparable findings, namely that the discrimination in addiction-related cues begins in the early stages of stimuli processing (e.g., Nijs et al., 2010; Versace, Minnix, Robinson, Lam, Brown, & Cinciripini, 2011; Yang, Zhang, & Zhao, 2015).

During a later, more controlled and more conscious stage of attentional bias, this study found lower LPP amplitude in porn addicts (high TCA group). The researchers suggest habituation/desensitization as possible explanations for this finding. From discussion:

This can be explained in several ways. First, cybersex addicts may experience habituation to still images. With the proliferation of pornographic content on the Internet, frequent users of online pornography are more likely to watch pornographic movies and short videos than still images. Given that pornographic videos generate higher physiological and subjective arousal than sexually explicit images, static pictures result in less sexual responsiveness (Both, Spiering, Everaerd, & Laan, 2004). Second, intense stimulation may cause significant neuroplastic changes (Kühn & Gallinat, 2014). Specifically, regularly viewing pornographic materials reduces the volume of gray matter in the dorsal striatum, a region related to sexual arousal (Arnow et al., 2002).

59) Alterations in oxytocin and vasopressin in men with problematic pornography use: The role of empathy [dysfunctional stress response] Excerpts:

findings suggest several alterations in neuropeptide functioning in PPU and demonstrate their links to lower empathy and more severe psychological symptoms. Furthermore, our findings suggest specific relationships between psychiatric symptomatology, AVP, oxytocin, empathy and pornography-related hypersexuality, and understanding these relationships may help guide clinical interventions….

Although preclinical studies repeatedly demonstrate alterations in oxytocin and AVP functionality in animal models of addiction, no prior human study has tested their joint involvement in people with PPU. The current results suggest alterations in oxytocin and AVP in men with PPU as expressed in baseline levels, reactivity patterns, neuropeptide balance, and links with pornography-related hypersexuality.

60) Neural and behavioral correlates of sexual stimuli anticipation point to addiction-like mechanisms in compulsive sexual behavior disorder (2022) [sensitization] This fMRI study found that porn/sex addicts (CSBD patients) have abnormal behavior and brain activity during anticipation of viewing porn, specifically in the ventral striatum. Furthermore, the study also found porn/sex addicts “wanted” porn more, but didn’t “like” it any more than healthy controls. Excerpts:

Importantly, these behavioral differences suggest that processes involving the anticipation of erotic and non-erotic stimuli may be altered in CSBD and support the idea that reward anticipation-related mechanisms similar to those in substance use disorders and behavioral addictions may play an important role in CSBD, as previously suggested (Chatzittofis et al., 2016; Gola et al., 2018; Jokinen et al., 2017; Kowalewska et al., 2018; Mechelmans et al., 2014; Politis et al., 2013; Schmidt et al., 2017; Sinke et al., 2020; Voon et al., 2014). This was further supported by the fact that we did not observe differences in other cognitive tasks measuring risk taking and impulse control, opposing the idea that general compulsivity-related mechanisms are at play (Norman et al., 2019; Mar, Townes, Pechlivanoglou, Arnold, & Schachar, 2022). Intriguingly, the behavioral measure ΔRT correlated negatively with hypersexuality symptoms and sexual compulsivity, indicating that anticipation-related behavioral alterations increase along with CSBD symptom severity….

Our findings suggest that CSBD is associated with altered behavioral correlates of anticipation, which further related to VS activity during anticipation of erotic stimuli. The findings support the idea that mechanisms similar as in substance and behavioral addictions play a role in CSBD and suggest that the classification of CSBD as an impulse-control disorder may be arguable on the basis of neurobiological findings.

61) Functional Connectivity in Compulsive Sexual Behavior Disorder – Systematic Review of Literature and Study on Heterosexual Males (2022) [sensitization]

We found increased fc between left inferior frontal gyrus and right planum temporale and polare, right and left insula, right Supplementary Motor Cortex (SMA), right parietal operculum, and also between left supramarginal gyrus and right planum polare, and between left orbitofrontal cortex and left insula when compared CSBD and HC. The decreased fc was observed between left middle temporal gyrus and bilateral insula and right parietal operculum.

The study was the first large sample study showing 5 distinct functional brain networks differentiating CSBD patients and HC.

The identified functional brain networks differentiate CSBD from HC and provide some support for incentive sensitization as mechanism underlying CSBD symptoms.

Together these neurological studies reported:

1. The 3 major addiction-related brain changes: sensitization, desensitization, and hypofrontality.
2. More porn use correlated with less grey matter in the reward circuit (dorsal striatum).
3. More porn use correlated with less reward circuit activation when briefly viewing sexual images.
4. And more porn use correlated with disrupted neural connections between the reward circuit and prefrontal cortex.
5. Addicts had greater prefrontal activity to sexual cues, but less brain activity to normal stimuli (matches drug addiction).
6. Porn use/exposure to porn related to greater delayed discounting (inability to delay gratification). This is a sign of poorer executive functioning.
7. 60% of compulsive porn addicted subjects in one study experienced ED or low libido with partners, but not with porn: all stated that internet porn use caused their ED/low libido.
8. Enhanced attentional bias comparable to drug users. Indicates sensitization (a product of DeltaFosb).
9. Greater wanting & craving for porn, but not greater liking. This aligns with the accepted model of addiction – incentive sensitization.
10. Porn addicts have greater preference for sexual novelty yet their brains habituated faster to sexual images. Not pre-existing.
11. The younger the porn users the greater the cue-induced reactivity in the reward center.
12. Higher EEG (P300) readings when porn users were exposed to porn cues (which occurs in other addictions).
13. Less desire for sex with a person correlating with greater cue-reactivity to porn images.
14. More porn use correlated with lower LPP amplitude when briefly viewing sexual photos: indicates habituation or desensitization.
15. Dysfunctional HPA axis and altered brain stress circuits, which occurs in drug addictions (and greater amygdala volume, which is associated with chronic social stress).
16. Epigenetic changes on genes central to the human stress response and closely associated with addiction.
17. Higher levels of Tumor Necrosis Factor (TNF) – which also occurs in drug abuse and addiction.
18. A deficit in temporal cortex gray matter; poorer connectivity between temporal corporate and several other regions.
19. Greater state impulsivity.
20. Decreased prefrontal cortex and anterior cingulate gyrus gray matter compared to healthy controls.
21. Reductions in white matter compared to healthy controls.

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Articles listing relevant studies and debunking misinformation:

Debunking misinformation:

1. Gary Wilson exposes the truth behind 5 studies propagandists cite to support their assertions that porn addiction doesn’t exist and that porn use is largely beneficial: Gary Wilson – Porn Research: Fact or Fiction (2018). 
2. Debunking “Why Are We Still So Worried About Wat­­ching Porn?”, by Marty Klein, Taylor Kohut, and Nicole Prause (2018).
3. How to recognize biased Articles: They cite Prause et al. 2015 (falsely claiming it debunks porn addiction), while omitting over 40 neurological studies supporting porn addiction.
4. If you are looking for an analysis of a study that you cannot find on this “Critiques of Questionable & Misleading Studies” page, check this page: Porn Science Deniers Alliance (AKA: “RealYourBrainOnPorn.com” and “PornographyResearch.com”). It examines the YBOP trademark infringers’ “research page,” including its cherry-picked outlier studies, bias, egregious omission, and deception.
5. Is Joshua Grubbs pulling the wool over our eyes with his “perceived porn addiction” research? (2016)
6. Research suggests the Grubbs, Perry, Wilt, Reid review is disingenuous (“Pornography Problems Due to Moral Incongruence: An Integrative Model with a Systematic Review and Meta-Analysis”) 2018.
7. Religious People Use Less Porn and Are No More Likely to Believe They Are Addicted (2017)
8. Critique of: Letter to the editor “Prause et al. (2015) the latest falsification of addiction predictions”
9. Op-ed: Who exactly is misrepresenting the science on pornography? (2016) 
10. Debunking Justin Lehmiller’s “Is Erectile Dysfunction Really on the Rise in Young Men” (2018)
11. Debunking Kris Taylor’s “A few hard truths about porn and erectile dysfunction” (2017)
12. And Debunking “Should you be worried about porn-induced erectile dysfunction?” – by The Daily Dot’s Claire Downs. (2018)
13. Debunking the “Men’s Health” article by Gavin Evans: “Can Watching Too Much Porn Give You Erectile Dysfunction?” (2018)
14. How porn is messing with your manhood, by Philip Zimbardo, Gary Wilson & Nikita Coulombe (March, 2016)
15. More on porn: guard your manhood—a response to Marty Klein, by Philip Zimbardo & Gary Wilson (April, 2016)
16. Dismantling David Ley’s response to Philip Zimbardo: “We must rely on good science in porn debate” (March, 2016)
17. YBOP response to Jim Pfaus’s “Trust a scientist: sex addiction is a myth” (January, 2016)
18. YBOP response to claims in a David Ley comment (January, 2016)
19. Sexologists deny porn-induced ED by claiming masturbation is the problem (2016)
20. David Ley attacks the Nofap movement (May, 2015)
21. RealYourBrainOnPorn tweets: Daniel Burgess, Nicole Prause & pro-porn allies create a biased website and social media accounts to support the porn industry agenda (beginning in April, 2019).
22. Prause’s efforts to silence Wilson foiled; her restraining order denied as frivolous & she owes substantial attorney fees in a SLAPP ruling.
23. Is Calling It Porn Addiction Dangerous? Video debunking Madita Oeming’s “Why We Need To Stop Calling It Porn Addiction“.

Lists of relevant studies (with excerpts):

• Porn and sexual problems? This list contains over 40 studies linking porn use/porn addiction to sexual problems and lower arousal to sexual stimuli. The first 7 studies in the list demonstrate causation, as participants eliminated porn use and healed chronic sexual dysfunctions.
• Porn’s effects on relationships? Over 80 studies link porn use to less sexual and relationship satisfaction.
• Porn use affecting emotional and mental health? Over 85 studies link porn use to poorer mental-emotional health & poorer cognitive outcomes.
• Porn use affecting beliefs, attitudes and behaviors? Over 40 studies link porn use to “un-egalitarian attitudes” toward women and sexist views.
• Over 60 studies reporting findings consistent with escalation of porn use (tolerance), habituation to porn, and even withdrawal symptoms (all signs and symptoms associated with addiction).
• Debunking the unsupported talking point that “high sexual desire” explains away porn or sex addiction: Over 25 studies falsify the claim that sex & porn addicts “just have high sexual desire”.

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