Mental health

Sex addiction affects brain in 'same way as drugs'

“Is compulsive sexual behaviour comparable to drug addiction?” asked The Guardian today.

This and other related headlines came from a UK study that looked at brain scans of 19 men with compulsive sexual behaviour (CSB) while they watched either sexually explicit, erotic or non-sexual videos.

CSB is a not a well-established diagnosis as it does not have a formal, universally accepted, definition. It has been described as the inability to control the sexual urges, behaviour or thoughts, often with negative consequences for the individual concerned.

Examples given in the study include spending large amounts of money on escort services and losing a job due to viewing pornography at work.

The study indicated that some areas of the brain were activated more when viewing sexually explicit content in men with CSB than in similarly aged men without the disorder.

Given the pattern of brain activity and other ratings of desire, the researchers indicated that the behaviour showed similarities with drug addiction. However, this comparison was theoretical and was not actually tested in this study.

The research did not involve many men, so the results cannot be taken as definitive. Research in larger groups will be needed to confirm these initial observations and to increase confidence that the observations are true in more general terms.

It is hoped that these initial investigations will give addiction researchers some focus for future research into the condition, which has been poorly studied.

Where did the story come from?

The study was carried out by researchers from the University of Cambridge and was funded by the Wellcome Trust, National Institutes for Health (US) and the National Centre for Responsible Gaming.

The study was published in the peer-reviewed medical journal PLOS One. This is an open-access journal, so the study is free to read online.

Generally, the media reported the facts of the study accurately. The Guardian provided especially useful background context on the issue of CSB and pornography.

What kind of research was this?

This was a human study investigating the brain activity of men who had compulsive sexual behaviour.

CSB was described in the paper as excessive or problematic engagement in sex, which has also been described as “sex addiction”. Like other compulsive disorders, this is far more than just enjoying sex a lot.

It is described as the inability to control sexual urges, behaviours or thoughts, which often has a detrimental effect on the person’s life, such as not being able to engage in stable relationships.

They may not actually want or enjoy what they are doing. The researchers suggest CSB may have common brain signals and networks as other natural and drug addictions. The researchers say little is known about how the brain reacts to sexually explicit material in individuals with CSB and those without – so the researchers decided to find out.

Studying brain activity is a common tool for indicating which areas of the brain are triggered and active during different stimuli. During the scans, researchers see areas of the brain light up corresponding to activity and, depending on the area, can infer whether this is in areas of reward, fear, excitement and other emotions and responses.

What did the research involve?

Researchers scanned the brains of 19 men with CSB while watching videos – some sexually explicit, some erotic and others non-sexual – to compare the brain activity in each scenario. They also asked the men to rate their sexual desire and whether they liked the videos. The same experiment was carried out with 19 age-matched healthy volunteers without CSB, to act as a comparison group.

Men with CSB were recruited via internet-based advertisements or referrals from therapists, and were interviewed by a psychiatrist to ensure that they met diagnostic criteria for the disorder. They were aged over 18 (with an average age of 25.6 years), heterosexual and free from any other compulsive disorders or serious mental health issues. The men filled in questionnaires assessing their impulsivity, depression, anxiety, alcohol dependence and intelligence. Age-matched heterosexual males without CSB were recruited by community advertisement.

Two of the 19 CSB subjects were taking antidepressants or had coexisting generalised anxiety disorder and social phobia (two of them), social phobia (one of them), or a childhood history of ADHD (one of them). One man with CSB and one healthy volunteer used cannabis intermittently.

The team used functional magnetic resonance imaging to observe changes in brain activity while the men watched the videos.

What were the basic results?

There were both similarities and differences in the brain responses of men with CSB and those without. Sexual desire or watching of the explicit sexual videos was linked to activation in a part of the brain called dACC ventral striatal-amygdala functional network across both groups. However, it was more strongly activated and linked to sexual desire in the CSB group.

Sexual desire ratings to explicit videos were greater in men with CSB compared to healthy volunteers, but not to erotic cues, whereas liking ratings to erotic cues were greater in CSB compared to healthy volunteers, but not to explicit cues. This showed that men’s rating of desire and liking were not always related.

The researchers said that the dissociation between desire and liking is consistent with theories of motivation underlying CSB seen in drug addictions.

How did the researchers interpret the results?

The researchers highlighted similarities between the brain activity they had observed in men with CSB and similar findings from other research in the brains of drug addicts.


This observational study used the brain scans of 19 men with CSB to point to some areas of the brain that were activated more when viewing sexually explicit content, compared with men without the compulsive behaviour.

There were many similarities between the brains and responses of men with and without CSB, indicating that the distinction was complex and overlapping. However, some areas were identified as being more active in men with CSB. This gives researchers in the field of addiction a better focus for future research.

The research did not compare the brains of men with CSB to those people with substance misuse, or those with other forms of addiction (such as gambling), to look for differences directly. These comparisons were theoretical and were not tested empirically in this study.

Given the research involved so few men, the results cannot be taken as definitive. More research in larger groups will be needed to confirm these initial observations and to increase confidence that the observations are true in more general terms.

It is important to note that there is no formal diagnostic criteria for CSB, and there is debate as to whether it should be labelled as a condition.

Similar debate has surrounded other addictive behaviour associated with excessive or compulsive use of the internet or computer games.

Research like this is important in understanding the brain biology and the psychological processes behind this behaviour – which often has a negative impact on a person’s life.

If you are concerned that a preoccupation with sex or sexual content online may be having a negative impact on your life, it is reassuring to know that there is help available.

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