MEDSCAPE: Cannabis Harms Brain, Imaging Shows

“Our study provides definitive evidence that in heavy cannabis users, there is a detectable deficit of striatal dopamine release using an amphetamine challenge,” said Dr Weinstein. “Within the striatum, the subdivisions seem to have a different pattern, in contrast to reports of other substance abuse. And our exploratory analysis suggests that the deficits we are seeing in dopamine release in the striatum have a functional significance — that lower dopamine release is associated with lower working memory and learning performance.”