A Massachusetts General Hospital (MGH) study finds that one month of abstaining from cannabis use resulted in measurable improvement in memory functions important for learning among adolescents and young adults who were regular cannabis users. The study published in the Journal of Clinical Psychiatry is one of the first to prospectively track over time changes in cognitive function associated with halting cannabis use.
“Our findings provide two pieces of convincing evidence,” says Randi Schuster, Ph.D., director of Neuropsychology at the Center for Addiction Medicine in the MGH Department of Psychiatry, lead author of the paper. “The first is that adolescents learn better when they are not using cannabis. The second—which is the good news part of the story—is that at least some of the deficits associated with cannabis use are not permanent and actually improve pretty quickly after cannabis use stops.”
The authors note that the use of cannabis among adolescents is common, with more than 13 percent of middle and high school students reporting cannabis use in a recent survey and rates of daily use increasing between grades 8 and 12. But adolescence is a critical time for brain maturation, specifically for brain regions that are most susceptible to the effects of cannabis. A 2016 study from the same research team found that cannabis users aged 16 and under had difficulty learning new information, a problem that was not observed in users age 17 and older.