1. Brain Structure and Functional Connectivity Associated With Pornography Consumption: The Brain on Porn (2014) – A German study which found 3 significant addiction-related brain changes correlating with the amount of porn consumed. It also found that more porn use correlated with less reward circuit activation while viewing sexual photos. Researchers stated their findings indicated desensitization, and possibly tolerance, which is the need for greater stimulation.
2. Neural Correlates of Sexual Cue Reactivity in Individuals with and without Compulsive Sexual Behaviours (2014) – The first in a series of Cambridge University studies found the same brain activity as seen in drug addicts and alcoholics. It also found that porn addicts fit the accepted addiction model of wanting “it” more, but not liking “it” more. 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.
3. Enhanced Attentional Bias towards Sexually Explicit Cues in Individuals with and without Compulsive Sexual Behaviours (2014) – 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].“
4. Novelty, Conditioning and Attentional Bias to Sexual Rewards (2015) – 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, porn addiction drives novelty-seeking in an attempt to overcome habituation and desensitization.
5. Neural Substrates of Sexual Desire in Individuals with Problematic Hypersexual Behavior (2015) – 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.
6. Sexual Desire, not Hypersexuality, is Related to Neurophysiological Responses Elicited by Sexual Images (2013) – This EEG study was touted in the media as evidence against the existence of porn addiction. Not so. This SPAN Lab study, like #7 below, actually lends support to the existence of porn addiction. How so? The study reported higher EEG readings (P300) 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. However, due to methodological flaws the findings are uninterpretable: 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 addiction. In line with the Cambridge University brain scan studies, this EEG study reported greater cue-reactivity to porn correlated with less desire for partnered sex. To put another way – individuals with more brain activation and cravings for porn would rather masturbate to porn than have sex with a real person. Study spokesman Nicole Prause claimed that porn users merely had high libido, yet the results of the study say something quite different. Three peer-reviewed papers expose the truth: 1, 2, 3, 4.  Read an extensive critique here.
7. Modulation of Late Positive Potentials by Sexual Images in Problem Users and Controls Inconsistent with “Porn Addiction” (2015) – Another SPAN Lab EEG study comparing the 2013 subjects from the above study to an actual control group. The results: compared to controls porn addicts had less response to photos of vanilla porn. The lead author, Nicole Prause, claims these results debunk porn addiction. However,  these findings align perfectly with Kühn & Gallinat (2014), which found that more porn use correlated with less brain activation in response to pictures of vanilla porn. Another EEG study found that greater porn use in women correlated with less brain activation to porn. Put simply, frequent porn users were desensitized and needed greater stimulation to achieve the same buzz or become aroused. Five peer-reviewed papers agree with this analysis of the study – 1, 2, 3, 4, 5. Read an extensive critique here.
8. HPA axis dysregulation in men with hypersexual disorder (2015) – 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 drug addiction.
9. Can pornography be addictive? An fMRI study of men seeking treatment for problematic pornography use (2016) – (in the press) Excerpts: Men with and without problematic porn sue (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.
10. Ventral striatum activity when watching preferred pornographic pictures is correlated with symptoms of Internet pornography addiction (2016) – 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.“
11. Altered Appetitive Conditioning and Neural Connectivity in Subjects With Compulsive Sexual Behavior (2016) – A German fMRI study replicating two major findings from Voon et al., 2014 and Kuhn & Gallinat 2014. Compared to controls compulsive porn users had 1) greater conditioned cue-induced activity in the amygdala, while having 2) decreased coupling between the ventral striatum and the prefrontal cortex. Number 1 indicates sensitization, while number 2 indicates hypofronatlity. In addition, 3 of the 20 compulsive porn users suffered from “orgasmic-erection disorder”.
12. Compulsivity across the pathological misuse of drug and non-drug rewards (2016) – A Cambridge University study comparing aspects of compulsivity in alcoholics, binge-eaters, video game addicts and porn addicts (CSB). Excerpts: CSB subjects were faster to learning from rewards in the acquisition phase compared to healthy volunteers and were more likely to perseverate or stay after either a loss or a win in the Reward condition. 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). 
13. Preliminary investigation of the impulsive and neuroanatomical characteristics of compulsive sexual behavior (2009) – Primarily sex addicts. Study reports more impulsive behavior in a Go-NoGo task in sex addicts (hypersexuals) compared to control participants. Brain scans revealed that sex addicts had greater disorganized prefrontal cortex white matter. This finding is consistent with hypofrontality, a hallmark of addiction.
14. Watching Pornographic Pictures on the Internet: Role of Sexual Arousal Ratings and Psychological-Psychiatric Symptoms for Using Internet Sex Sites Excessively (2011) – 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 
15. Pornographic picture processing interferes with working memory performance (2013) – 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.
16. Sexual Picture Processing Interferes with Decision-Making Under Ambiguity (2013) – 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.
17. Cybersex addiction: Experienced sexual arousal when watching pornography and not real-life sexual contacts makes the difference (2013) – 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.
18. Empirical Evidence and Theoretical Considerations on Factors Contributing to Cybersex Addiction From a Cognitive-Behavioral View (2014) – Dysfunctional use of sex mediated the relationship of sexual excitability with cybersex addiction (CA). 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 cybersex addiction. 
19. Cybersex addiction in heterosexual female users of internet pornography can be explained by gratification hypothesis (2014) – Results indicated that Internet porn users rated pornographic pictures as more arousing and reported greater craving due to pornographic picture presentation compared with non-users. 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 porn users. Being in a relationship, number of sexual contacts, satisfaction with sexual contacts, and use of interactive cybersex were not associated with cybersex addiction.
20. Prefrontal control and internet addiction: a theoretical model and review of neuropsychological and neuroimaging findings (2015) – 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.
21. Implicit associations in cybersex addiction: Adaption of an Implicit Association Test with pornographic pictures. (2015) – 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. 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.
22. Symptoms of cybersex addiction can be linked to both approaching and avoiding pornographic stimuli: results from an analog sample of regular cybersex users (2015) – 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.
23. Getting stuck with pornography? Overuse or neglect of cybersex cues in a multitasking situation is related to symptoms of cybersex addiction (2015) – 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. The results of the current study point towards a role of executive control functions, i.e. functions mediated by the prefrontal cortex, for the development and maintenance of problematic cybersex use (as suggested by Brand et al., 2014). Particularly a reduced ability to monitor consumption and to switch between pornographic material and other contents in a goal adequate manner may be one mechanism in the development and maintenance of cybersex addiction.
24. Trading Later Rewards for Current Pleasure: Pornography Consumption and Delay Discounting (2015) –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. 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.
25. Sexual Excitability and Dysfunctional Coping Determine Cybersex Addiction in Homosexual Males (2015) – 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.
26. Subjective Craving for Pornography and Associative Learning Predict Tendencies Towards Cybersex Addiction in a Sample of Regular Cybersex Users (2016) – 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
27. Exploring the Relationship between Sexual Compulsivity and Attentional Bias to Sex-Related Words in a Cohort of Sexually Active Individuals (2016) – This study replicates the findings of this 2014 Cambridge University study that compared the attentional bias of porn addicts to healthy controls. The new study differs: rather than comparing porn addicts to controls, the new study correlated scores on a sex addiction questionnaire to the results of a task assessing attentional bias (explanation of attentional bias). The study described two key results: 1) Higher sexual compulsivity scores correlated with greater interference (increased distraction) during the attentional bias task. This aligns with substance abuse studies. 2) Among those scoring high on sexual addiction, fewer years of sexual experience were related to greater attentional bias. 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 section: “One possible explanation for these results is that as a sexually compulsive individual engages in more compulsive behaviour, an associated arousal template develops 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.”
28. Compulsive sexual behavior: Prefrontal and limbic volume and interactions (2016) – Compared to healthy controls, porn addicts had increased left amygdala volume and reduced functional connectivity between the amygdala and dorsolateral prefrontal cortex in the brain. 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 gray 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 is very stressful – and chronic social stress is related to increased amygdala volume. Another study on this list found that “sex addicts” have a overactive stress system. Could the chronic stress related to porn/sex addiction, along with factors that make sex unique, lead to greater amygdala volume?
29. Mood changes after watching pornography on the Internet are linked to symptoms of Internet-pornography-viewing disorder (2016) – 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.

Together these brain studies found:

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 viewing sexual images.
4. 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 addicts have greater preference for sexual novelty yet their brains habituated faster to sexual images. Not pre-existing.
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. The younger the porn users the greater the cue-induced reactivity in the reward center.
11. Higher EEG (P300) readings when porn users were exposed to porn cues (which occurs in other addictions).
12. Less desire for sex with a person correlating with greater cue-reactivity to porn images.
13. More porn use related with lower LPP amplitude when viewing sexual photos: indicates habituation or desensitization.
14. Dysfunctional HPA axis which reflects altered brain stress circuits.