"Our findings indicated that gray matter volume of the right caudate of the striatum is smaller with higher pornography use," the researchers wrote in the journal article, referring to an area of the brain associated with reward processing and motivation. Men who watched more porn also showed less activity in another area of the striatum, called the left putamen, which usually lights up in response to sexual images.

Heavy porn consumers also had a weaker connection between the striatum and the prefrontal cortex, an area of the brain associated with decision-making.