The myths of smoking pot

As Colorado and Washington state approve the sale of marijuana for recreational use and other states consider following suit, Volkow says, the notion that legalization represents a modest, cost-free move is dangerously overblown. The evidence on the supposed safety of marijuana — particularly marijuana in its modern, far more potent form — is far from clear enough to take this leap.

“I think that what we are seeing is a little bit of wishful thinking in the sense that we want to have a drug that will make us all feel good and believe that there are no harmful consequences,” she said. “When you are intoxicated, your memory and learning are going to go down. When you are intoxicated, your motor coordination is going to go down. When you are repeatedly using marijuana, there is an increased risk for addiction. And if you are an adolescent and you are taking marijuana, there is a higher increased risk for addiction and there is also a higher risk for long-lasting decreases in cognitive capacity — that is, lowering of IQ.”

Adolescents are a chief focus of Volkow’s worry, to the extent that when I observe that tobacco use is clearly worse for teens, she challenges that easy assumption.