Grinspoon dismissed the modern idea that persistent marijuana use leads to schizophrenia or other mental health problems, though he said the IQ study is strong and the drug — like much of what is sold by prescription — is not harmless.
But Grinspoon has been collecting stories for years about people’s experience with marijuana for medical and casual use, and he believes it is a safer recreational drug than alcohol. Someday research will reveal it as “a wonder drug,” he said.
“I have always been against young people using it,” Grinspoon said. “If it turns out to be right [that marijuana harms brain development in adolescence], that’s the most urgent reason for us to get the prohibition defeated, to treat it like alcohol.”
Regulating marijuana would allow for better tracking and punishment of people who sell it to minors and would eliminate some of the “forbidden fruit motivation” for teens trying the drug, Grinspoon said.
It is not clear just what impact medical marijuana laws are having on usage among teens.
A study published last year by researchers at Columbia University’s Mailman School of Public Health found that people ages 12 to 17 were more likely to use the drug in states permitting medical marijuana. But some of those states already had higher usage rates before the laws were enacted, so researchers couldn’t rule out the possibility that the prevalence of marijuana use simply made some states more likely to pass the laws.
Massachusetts, which decriminalized possession of small amounts of marijuana in 2008, had one of the highest rates in the country last year of high school students reporting ever having used marijuana, at about 43 percent, up slightly since 2007.
The Children’s Hospital center launched a website two years ago aimed at teaching parents about how teens’ brains work and the effects of drug use. In a small study tracking students in the weeks after they attend classes about brain development and drugs, Harris found that such information may reduce the likelihood of teens using drugs in the short term.
“If we can increase the dosage of this kind of information, not just with adolescents, with parents, with the larger community, then we could make some headway,” Harris said.
It’s a newer take on the old public service announcement, without the hot frying pan and egg: “This is your brain on drugs.”