Last week, the Journal of the American Medical Association (JAMA) Psychiatry published a German study claiming there was a link between excessive pornography viewing and decreased brain volume.

Authored by the Max Planck Institute for Human Development in Berlin, the study took brain images of 64 men after polling them on their porn-watching habits. They found that the volume of the striatum, the area of the brain that’s commonly associated with “reward processing and motivated behavior,” was slightly decreased in those who reported watching lots of pornography compared to those who didn’t.

While the study’s authors were careful to note that the findings were not conclusive, they were enough to set the hair of every Pornhub-bookmarking man, woman, and teenager. A host of media outlets capitalized on what they perceived as the study’s “OMG PORN MAKES YOU STUPID” message. Jezebel’s headline screamed “People Who Watch Tons of Porn Have Smaller Brains,” while the Telegraph, channeling Chris Traeger, wrote: “Is porn literally shrinking men’s brains?”

There’s just one problem with this story: It might not actually be true.

The problem, says Dr. Nicole Prause of the University of California Los Angeles, is not with the study itself, but with the way the media interpreted it.

“It’s a great first study, and the authors are very cautious not to say this is causal, that these are just relationships [between decreased brain volume and porn viewing],” says Prause. “They did not show that porn causes brain atrophy and they didn’t claim that they did.”

But as any Psych 101 student knows, there’s an important distinction between causation and correlation. This, Prause says, is where the media’s interpretation of the study has gone wrong. With such a small sample size, there is no way to determine that watching porn causes brain changes; just that there’s a correlation between brain size and hours of porn watched.

Prause says that even the correlation between decreased brain volume and porn consumption is suspect, because the study’s authors failed to control for other factors, such as alcohol consumption and depression, which would also lead to decreased grey volume in these specific regions of the brain.

“Lots of studies have shown that certain brain regions are smaller in people who suffer from high levels of depression,” she says. “It could be that all [the study’s authors] are documenting is the depression effect, and people who are depressed also happen to watch more porn, which seems very reasonable to me.”

In short, it might not be the porn at all that’s causing the subjects’ brains to “shrink,” but other factors, like depression and lifestyle choices, that produce similar effects.

So, what if the authors of the German study did control for such factors as alcohol use and depression? What if it could, beyond any reasonable doubt, be established that watching two blonde ladies go to town on each other on Redtube caused changes to your brain’s size and functioning?

More research and follow-up studies are required to determine whether that’s actually the case. But even if it is, Prause says that it might not even matter. Contrary to the headlines screaming about how porn makes you “lazy” or “stupid,” the loss of grey matter does not necessarily equate to a marked change in brain activity. Put simply, having a smaller brain doesn’t make you stupid.

“Women’s brains are on average smaller than men’s, so if you’re making that claim, you’d be saying women are stupid, and obviously I’d say that isn’t the case,” Prause says with a laugh. “Differences you see in the brain don’t necessarily manifest in behavioral changes. ... if there’s functional loss, there might be a problem. But what type of problem it is, how it’s going to manifest, whether you can tell the difference, is a very different story.”

The fact is that lots of activities, be it watching porn or washing dishes, has been linked by researchers to changes in the brain: “Basically everything that people do very frequently can shape their brain structure and function,” Kuhn recently told Reuters about the study. As of now, there’s simply no way to determine for sure whether excessive porn consumption actually makes your brain smaller; or if men with slightly smaller brains, or preexisting conditions that might cause smaller brains, are somehow more predisposed to watching lots o’ porn.

The question of whether porn actually causes significant changes in the brain is one that will ultimately require tons of additional research before we can answer with the utmost certainty. But saying that excessive porn consumption may or may not yield such structural changes requires a lot more nuance and attention to detail than the media—which is already predisposed to blaming porn for many of society’s ills, from mass shootings to body image issues—is willing or able to invest.

Ultimately, when it comes to the question of whether porn is good or bad for us, there are many shades of gray (matter).

Update: Dr. Simone Kuhn of the Max Planck Institute for Human Development has commented via e-mail on the results of the study:  "Less grey matter does not mean that people are lazier or more stupid. We do not even know the direction of causality of this effect. It could be that porn causes this brain region to decrease, but it could also be that people with a small striatum like porn better." 

H/T Reuters | Photo by Lies Thru a Lens/Flickr (CC BY 2.0)