Watching Porn May Shrink Your Brain, Or Porn-Watchers May Already Have Smaller Brains, Finds Least Surprising Study Ever

While sex itself could potentially make you smarter, a new study has found that men who watch porn tend to have less grey matter (that's the clever part of brain made up of nerve-cell bodies), and less activity in the area of the brain associated with rewards. Which is making a lot of people conclude that porn makes you stupid. A tempting interpretation, no doubt, but not entirely accurate — the study proves only correlation, not causation, and so it could just be that men with smaller brains are more drawn to porn (which, let's face it, could be just as likely).

The very small study, published earlier this week and undertaken at the Max Planck Institute in Berlin, looked at the porn-watching habits of 64 healthy men between the ages of 21 and 45.(It didn't look at women at all, so whatever effects porn as on the female brain remain a mystery.) Researchers examined these habits alongside MRI scans of the mens' brains, looking at how they reacted when shown pornographic pictures.

Their results were pretty intuitive: the area of the brain that works when someone is rewarded or motivated shrinks and is less effective in people who watch a lot of porn, suggesting that the more a person watches, the more graphic the porn has to be in order to produce the same sexual response — in other words, a type of tolerance is built.“We found that the volume of the so-called striatum, a brain region that has been associated with reward processing and motivated behavior was smaller the more pornography consumption the participants reported," the researchers said.

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They also found "a significant negative association between reported pornography hours per week and gray matter volume," although that's not to say that these porn-watching men were necessarily dumber in some way — while grey matter has been linked with intelligence, scientists continue to debate how directly it affects cleverness, with many holding that it's more subtle characteristics that determine how smart you are.

What's really important to keep in mind is that the study couldn't prove causation, only correlation. Which, as Dr. Simone Kühn pointed out in an email to The Daily Beast, means “it is not even clear whether pornography consumption causes the brain to shrink, or whether the brain structure is the precondition that makes people vulnerable for pornography consumption.” In other words, are men with certain brain types (less efficient reward centers and smaller volumes of grey matter) more likely to watch porn? It would explain a lot, that's for sure.

Recently, another German study found that increased porn watching was associated with worse memory performance, although it too had a small sample size of only 28 people. Either way, porn isn't doing anyone any favors, but that much we could have guessed.