Pornography triggers brain activity in people with compulsive sexual behaviour - known commonly as sex addiction - similar to that triggered by drugs in the brains of drug addicts, researchers said.
However, the researchers caution that this does not necessarily mean that pornography itself is addictive.
Previous studies have suggested that as many as one in 25 adults is affected by compulsive sexual behaviour, an obsession with sexual thoughts, feelings or behaviour which they are unable to control.
This can have an impact on a person's personal life and work, leading to significant distress and feelings of shame.
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Researchers at the University of Cambridge looked at brain activity in 19 male patients affected by compulsive sexual behaviour and compared them to the same number of healthy volunteers.
The patients started watching pornography at earlier ages and in higher proportions relative to the healthy volunteers.
"The patients in our trial were all people who had substantial difficulties controlling their sexual behaviour and this was having significant consequences for them, affecting their lives and relationships," said Dr Valerie Voon, a Wellcome Trust Intermediate Clinical Fellow at Cambridge.
The participants were shown a series of short videos featuring either sexually explicit content or sports whilst their brain activity was monitored using functional magnetic resonance imaging (fMRI), which uses a blood oxygen level dependent (BOLD) signal to measure brain activity.
Researchers found that three regions in particular were more active in the brains of the people with compulsive sexual behaviour compared with the healthy volunteers.
Significantly, these regions - the ventral striatum, dorsal anterior cingulate and amygdala - were regions that are also particularly activated in drug addicts when shown drug stimuli.
Patients with compulsive sexual behaviour also showed higher levels of desire towards the sexually explicit videos, but did not necessarily rate them higher on liking scores.
The study was published in the journal PLOS ONE.