Watching pornography may shrink the brain and dull responses to sexual stimulation, researchers have suggested.
Scientists have found for the first time that regularly viewing sexual images could be physically harmful.
Researchers from the Max Planck Institute in Berlin found that a part of the brain which activates when people feel motivated or rewarded, shrinks and works less efficiently.
So people who watch a lot of porn are likely to need increasingly graphic material to achieve the same sexual stimulation.
For the study, Dr Kuhn and her colleague Jurgen Gallinat from Charite University, also in Berlin, recruited 64 healthy men between the ages of 21 and 45 years and asked them questions about their porn-watching habits.
They also took images of the men’s brains to measure volume and to see how their brains reacted to pornographic pictures.
They found noticeable differences in the men who abstained compared with those who regularly accessed sexual videos or images.
However other researchers claimed that pornography in moderation was probably not damaging.
“Everything is going to be bad in excess and it’s probably not terrible in moderation,” Dr Gregory Tau of the Columbia University
Dr Tau, who was not involved with the study, agreed that more research should be done in this area and that longer studies would be need to find out if porn leads to brain changes.
“It is possible that there are individuals with a certain kind of brain that are more susceptible to these kinds of behaviors,” he said.
The study was published in JAMA Psychiatry.