The study suggests that the brains of heavy porn users show signs of degradation and shrinkage.
Researchers at the Max Planck Institute for Human Development in Berlin found that men who watch a lot of porn tend to have a smaller striatum, an area of the brain "linked to rewards and motivation".
They also found that the connection between the striatum and the prefrontal cortex - the part of the brain associated with behaviour and decision making degraded with increased porn watching, 'The Telegraph' reported.
Although the study suggests that porn causes the brain to shrink, researchers cautioned it could be that people with smaller brains are more attracted to porn.
For the study, sixty-four healthy male adults with a broad range of pornography consumption reported hours of pornography consumption per week.
Pornography consumption was associated with neural structure, task-related activation, and functional resting-state connectivity.
Gray matter volume of the brain as measured by voxel-based morphometry and resting state functional connectivity was measured on magnetic resonance imaging scans.
"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," researchers wrote in the journal JAMA Psychiatry.
"Functional connectivity of the right caudate to the left dorsolateral prefrontal cortex was negatively associated with hours of pornography consumption," they said.