Researchers from the Max Planck Institute for Human Development in Berlin have published a study in the journal JAMA Psychiatry which found that hours spent watching pornography was associated with differences in gray matter volume in a particular region of the brain.

For the investigation, scientists recruited 64 healthy males between the ages of 21-45. Participants were asked to fill out surveys on the amount of time spent watching porn per week, which was found to vary considerably between participants. Typically, the men were found to not spend more than 4 hours per week viewing pornographic material.

The brains of the men were then scanned using magnetic resonance imaging (MRI) whilst they were either being shown pornographic images or non-sexual images. They found a negative association between time spent watching porn and gray matter volume of the right caudate of the striatum. When the men were being shown pornographic material, the MRI scans also revealed an apparent decrease in function of a brain region known to process motivation. Furthermore, functional connectivity between the right caudate and the left dorsolateral prefrontal cortex was negatively associated with the amount of reported time watching porn.

Since the researchers cannot prove that it is the porn that caused this decrease in gray matter volume, they have called for further investigation. “Future studies should investigate the effects of pornography longitudinally or expose naïve participants to pornography and investigate causal effects over time,” said the researchers. The former would probably be easier to gain approval from an ethics committee!

The researchers acknowledge that they are uncertain at this stage as to what the results mean, however, they have a couple of hypotheses. It could be that excessive stimulation of the reward system has resulted in alterations in neural plasticity. On the flip side, it could be that men with less gray matter in the striatum require more stimulation than others and find watching porn more rewarding, which could lead to an increase in porn consumption.

This study is preliminary and once again, the researchers acknowledge that further investigation is needed with a more rigorous methodology before conclusions can be drawn.

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