“But the bottom line is that long-term, heavy cannabis use may impair the dopaminergic system, which could have a variety of negative effects on learning and behavior,” said Dr. Anissa Abi-Dargham, professor of psychiatry and a lead author of the paper.
 
“I used to be able to read a book and even after a couple years I would still know most of the book,” she said. “Now I have to read something four or five times to remember.”