NBC News (8/27, Fox) reports on two studies published in JAMA Psychiatry that examine the effect of marijuana on the brain. In the first study, “David Pagliaccio, formerly of Washington University in St. Louis and now at the National Institute of Mental Health, and colleagues” compared the brains of marijuana users to non-users.
The results seemed to suggest that marijuana users “had some shrinkage in two brain regions called the amygdala and the right ventral striatum,” but when researchers compared marijuana users to their siblings, “the differences disappeared.” Meanwhile, a second study “found that marijuana appears to change the brain structure of young men with a high genetic risk of schizophrenia.” Dr. David Goldman, of the National Institute on Alcohol Abuse and Alcoholism, said the studies don’t offer a clear picture of anything, adding, “It’s probably more a story of what we don’t know than what we do know.”
According to HealthDay (8/27, Thompson), Dr. Goldman wrote, “The burden of cannabis’ effects may fall more heavily on people who, because of genetic makeup or early life exposures, are at greatest risk for brain structural changes, psychosis or addiction.” He added “It is safer not to expose people to psychoactive drugs.”
— “Marijuana Doesn’t Shrink Brains, But It Can Change Them, Studies Find,” Maggie Fox, NBC News, August 27, 2015.