A new brain scanning study just about to be published in a prestigious academic journal, finds that consumption of pornography in men is associated with smaller cerebral gray matter volume, and lower connectivity, in certain cortical regions.
One theory that Dr Simone Kühn and Dr Jürgen Gallinat, the authors of the study, propose, is that more pornography consumption actually damages the brain, or at least reduces its volume in certain areas. As the brains of men who consume more pornography are found, by this study, to be clearly different, an alternative explanation is that it is also possible certain brain types predict which men are going to find erotica more rewarding.
The 64 otherwise healthy male participants, who were brain scanned in the study, reported on average 4.09 hours a week of consuming pornography.
A particularly intriguing result was that the reduction in gray matter volume found in the specific brain region, could not be accounted for by accompanying internet or sex addiction. In other words, there appeared to be something specific about more hours spent a week consuming pornography, which was particularly linked to lower cerebral gray matter volumes in certain brain regions.
The authors of the study, from the Max Planck Institute for Human Development, Berlin, and the University Clinic for Psychiatry and Psychotherapy, Hamburg, were partly prompted to conduct the research, because of recent data from the United States showing 66% of men and 41% of women (perhaps because of the recent impact of the Internet) consume pornography on a monthly basis. The authors also quote estimates that 50% of all Internet traffic is related to sex.
The consumption of erotica may be based on strong biological drives. This is possibly illustrated by another study quoted by Dr Kühn and Dr Gallinat - that male monkeys gave up juice rewards to watch pictures of female monkeys' bottoms. In other words, for monkeys at least, consuming the ape equivalent of porn, could be more important than food or drink.
The study, entitled, Brain Structure and Functional Connectivity Associated With Pornography Consumption - The Brain on Porn, suggests that intense exposure to pornography results in a reduction of the natural neural response to sexual stimuli. This might explain a previous research finding that higher pornography consumption in men is associated with generally poorer relationship quality.
The study, published in the Journal of the American Medical Association Psychiatry, also found an association between increased pornography use and depression as well as alcohol use, suggesting that consuming erotica could be associated with other psychiatric problems.
The authors point out that similar kinds of brain volume differences in these same regions have previously been associated with addiction to all kinds of drugs such as cocaine, methamphetamine and alcohol. They argue this indicates that increased pornography use may be linked to neural addiction processes.
Dr Simone Kühn and Dr Jürgen Gallinat conclude their report by arguing one possible interpretation of their data is that the frequent brain activation caused by pornography exposure could lead to structural 'wearing' and reduced activity of the underlying brain regions. This in turn results in a higher need for external stimulation of this reward system. This then produces a tendency to search for novel and more extreme sexual material.
This might explain the decline in satisfaction in the sex life of relationships that has been reported as accompanying greater pornography usage. Clinical experience within sexual therapy however suggests that pornography within a consenting couple relationship can sometimes enhance sex lives. It seems also possible that greater use of pornography could on occasions be a result of lowered erotic fulfilment in a relationship.
However, the authors point to a representative recent study on adolescent boys where daily erotica consumption was associated with more interest in deviant and illegal types of pornography. Such consumption has also been linked with more frequently reported wishes to actualize what was seen, in real life. Some investigators have found heavy consumers of pornography seem to want to execute 'pornography scripts' in real life.
This self-perpetuating process could be similar to proposed mechanisms in drug addiction. Taking drugs reduces longer term activity in the brain rewards centres, which then leads to the craving for more stimulants to get those parts of the brain as active as before.
The authors caution however that the observed brain volume association with pornography use could likewise be a 'pre-condition', rather than a consequence, of frequent pornography consumption. Individuals with lower brain volume in these reward centres may need more external stimulation to experience pleasure, and might therefore experience pornography consumption as more rewarding.
In other words, the finding of brain differences in those who consume more pornography may explain the tendency to use, rather than being a consequence of it.
The only way to uncover what is really happening to the 'brain on porn' would be to conduct a kind of study where people (including those with no previous interest in erotica) are randomised to groups who are given a lot of sexual material to consume, while others are given 'control' alternatives, and then brain scans of the groups are compared. However, there are possible ethical and other problems with such a study.
This means we may never know which comes first - whether the brain differences found in this new research, predispose to more pornography use, or whether more usage brings about brain changes.
If the internet means pornography is no longer a minority interest, but instead has become a mass phenomenon, with a widening impact on general society, then this new finding of reduced brain activity and volume in certain areas, might suggest millions of people may be unknowingly altering their brains by consuming more erotica.
If 50% of all Internet traffic is related to sex, then that's a lot brain volume being shrunk.