A new German study shows that men who view too much pornography may become lazier.

Greater use of pornography by men in the study was associated with a decreased volume of brain matter in areas related to reward and motivation, say researchers at the Max Planck Institute for Human Development in Berlin.

“We found a significant negative association between reported pornography hours per week and gray matter volume in the right caudate as well as with functional activity during a sexual cue–reactivity paradigm in the left putamen,” the researchers wrote in the study, published Wednesday in JAMA Psychiatry. “Functional connectivity of the right caudate to the left dorsolateral prefrontal cortex was negatively associated with hours of pornography consumption.”

The study is the first to provide strong evidence that pornography might harm the brain in some ways, says study leader Simone Kühn. She and her colleagues recruited 64 healthy German men between the ages of 21 and 45 years old, inquiring about their consumption of pornography. They then studied the participants’ brains with functional magnetic resonance imaging, watching to see how the brain reacted to pornography.

“We found that the volume of the so-called striatum, a brain region that has been associated with reward processing and motivated behaviour was smaller the more pornography consumption the participants reported,” Kühn told reporters, according to the Daily Mail. “Moreover we found that another brain region, that is also part of the striatum that is active when people see sexual stimuli, shows less activation the more pornography participants consumed,” she said.

In essence, the connectivity between the brain’s striatum and prefrontal cortex worsened with increased consumption of pornography, suggesting poorer and impaired decision-making capability. But the researchers decline to say the study proves any causal relationship between greater pornography use and lowered connectivity associated with behavioral changes. Such behavioral changes might reflect a neuroplasticity in the brain’s reward system, or maybe it’s the other way around.

In this case, the researchers had wondered how pornography would alter the brain’s frontostriatal network among the heaviest users. Assuming that pornography consumption is like other reward-seeking human behaviors, they hypothesized that very frequent use would surely change how the brain works.

“Basically everything that people do very frequently can shape their brain structure and function,” Kühn said.

 

Source: Kühn S, Gallinat J. Brain Structure and Functional Connectivity Associated With Pornography Consumption: The Brain on Porn. JAMA Psychiatry. 2014.