Brain scans of nearly 1,000 past and present marijuana users revealed abnormally low blood flow throughout their brains, compared with a smaller control group of 92 people who'd never used pot.
"The differences were astonishing," said lead researcher Dr. Daniel Amen, a psychiatrist and founder of the U.S.-based Amen Clinics. "Virtually every area of the brain we measured was lower in blood flow and activity in the marijuana smokers than in the healthy group." Blood flow was lowest in the hippocampus of marijuana users, which Amen found most troubling.
