Less grey matter is found in the brains of men who watch large amounts of sexually explicit material, a study has found. The research, published in the journal JAMA Psychiatry, could not determine if porn actually caused the brain to shrink, however, and the authors called for more study on the topic.”Future studies should investigate the effects of pornography longitudinally or expose naive participants to pornography and investigate the causal effects over time,” said researchers at the Max Planck Institute for Human Development in Berlin.
http://www.theguardian.com/culture/2014/may/29/porn-viewing-linked-less-grey-matter-brain