According to a new study just published in the journal Hippocampus, adolescents who were once heavy marijuana users have abnormally-shaped hippocampus—an area of the brain that controls long-term memory. The damage reportedly lasted years after the teenagers stopped smoking marijuana.
A team of researchers at Northwestern University in Evanston, Illinois studied volunteers who had smoked marijuana for approximately three years starting at age 16 or 17 but did not use other drugs. (The subjects had not yet been smoking for two years when the study began.) The investigative team compared these participants with a control group as well as a group of subjects suffering from different psychiatric disorders.
Following a brain scan, the volunteers took a memory examination. They listened to different stories and then recalled as much as possible 20 or 30 minutes later.
Those who had been heavy pot smokers as teenagers scored 26 percent poorer on the test than non-smokers who had schizophrenia. The investigators believe this was, as brain scans seemed to indicate, the former marijuana users had hippocampus damage.
Northwestern Medicine researcher, Matthew Smith, PhD stated: “What we found was the differences in the hippocampus shape were directly related to performing more poorly on memory assessments.”
Additionally, those who were heavy marijuana users scored 18 percent lower on long-term memory assessments in comparison to the subjects who never used cannabis. Smith continued:
“So what the findings suggest is there may be a sustained effect of marijuana on the brain. I think one of the main implications; if you introduce a drug into the brains of adolescents the adolescent brain is maturing and doing a lot of things to prepare for adulthood. That can alter the development of the adolescent brain.”
The researchers report that the longer the teenagers were heavy marijuana smokers the more abnormal the hippocampus. They note that this specific area of the brain is more than likely susceptible to marijuana because it’s thick with THC receptors — a cannabinoid that is found in marijuana.
Adolescent Marijuana Use Affects Memory