Watch porn and your brain may suffer from the intense stimulation of the reward system. One of the results of this can be a lower top-down modulation of prefrontal cortical areas (i.e., a loss of executive function and the ability to associate behaviors with outcomes). Another outcome is that exposure to porn imagery produced reduced activation in parts of brain associated with motivation - suggesting that porn (like other drugs) reduces the desire to do anything other than look at porn.
The researchers point out, rightly, that they cannot say that porn reduces grey matter - only that those who watch more porn has less grey matter. It may be the later that leads to the former.
By the way, the average porn consumption for the 64 men was 4 hours a week.
Below is a summary of the research from Science Alert, followed by the abstract of the full article (which is sequestered behind a pay wall).
Porn consumption has been linked to differences in the structure and function of male brains
Felicity Nelson | Saturday, 31 May 2014
Men who watch porn have significantly less grey matter in their brains, a new study shows. MRI brain scans of 64 men between 21 and 45 years of age were taken while participants were shown images of porn and people exercising.
The participants were later requested to provide information about weekly porn consumption via a phone interview. Every person in the study volunteered to answer these questions, even though they were not told that this information would be needed before commencing. The men had a wide range of porn consumption averaging 4 hours a week.
Men with higher porn consumption had lower grey matter volumes. Interestingly, when men were shown sexually explicit material during the MRI scan, the region of the brain associated with motivation showed reduced activity.
"Our findings indicated that grey matter volume of the right caudate of the striatum is smaller with higher pornography use," researchers at the Max Planck Institute for Human Development in Berlin, Germany told ABC Science.
The study could not show that porn caused men's brains to lose grey matter. "Future studies should investigate the effects of pornography longitudinally or expose naive participants to pornography and investigate the causal effects over time", researchers told ABC Science.
This research was published this week in the journal JAMA Psychiatry.
Kühn, S; Gallinat, J. (2014, May 28). Brain Structure and Functional Connectivity Associated With Pornography Consumption. JAMA Psychiatry. Online First. doi:10.1001/jamapsychiatry.2014.93
The Brain on Porn ONLINE FIRSTSimone Kühn, PhD; Jürgen Gallinat, PhD
Importance Since pornography appeared on the Internet, the accessibility, affordability, and anonymity of consuming visual sexual stimuli have increased and attracted millions of users. Based on the assumption that pornography consumption bears resemblance with reward-seeking behavior, novelty-seeking behavior, and addictive behavior, we hypothesized alterations of the frontostriatal network in frequent users.
Objective To determine whether frequent pornography consumption is associated with the frontostriatal network.
Design, Setting, and Participants Sixty-four healthy male adults with a broad range of pornography consumption at the Max Planck Institute for Human Development in Berlin, Germany, reported hours of pornography consumption per week. Pornography consumption was associated with neural structure, task-related activation, and functional resting-state connectivity.
Main Outcomes and Measures Gray matter volume of the brain was measured by voxel-based morphometry and resting state functional connectivity was measured on 3-T magnetic resonance imaging scans.
Results We found a significant negative association between reported pornography hours per week and gray matter volume in the right caudate (P < .001, corrected for multiple comparisons) as well as with functional activity during a sexual cue–reactivity paradigm in the left putamen (P< .001). Functional connectivity of the right caudate to the left dorsolateral prefrontal cortex was negatively associated with hours of pornography consumption.
Conclusions and Relevance The negative association of self-reported pornography consumption with the right striatum (caudate) volume, left striatum (putamen) activation during cue reactivity, and lower functional connectivity of the right caudate to the left dorsolateral prefrontal cortex could reflect change in neural plasticity as a consequence of an intense stimulation of the reward system, together with a lower top-down modulation of prefrontal cortical areas. Alternatively, it could be a precondition that makes pornography consumption more rewarding.