January 27, 2014
Marijuana Hurts the Brain Circuitry
“Adolescence is a sensitive time for brain development,” says Matthew J. Smith, a research assistant professor of psychiatry and behavioral sciences. “If a teen introduces the abuse of marijuana at that point in their life, it could have consequences for their ability to problem solve, for their memory and for critical thinking in general.”
Unfortunately, this crucial message is getting lost in the pro-legalization fervor. Use of pot among adolescents, which had declined from the late 1990s through the mid-to-late 2000s, is again on the rise, according to the National Institute on Drug Abuse. One likely reason: “The percentage of high-schoolers who see great risk from being regular marijuana users has dropped,” over time the agency points out.
That perception, however, is all wrong. In a study published last month, Smith and his colleagues found that teens who smoked a lot of pot had abnormal changes in their brain structures related to working memory—a predictor of weak academic performance and impaired everyday functioning—and that they did poorly on memory-related tasks.
While the study focused on heavy marijuana users—specifically, those who indulged daily for about three years—one of its most crucial findings related not to the amount of pot an adolescent smoked, but when he or she started: The earlier the drug was taken up, the worse the effects on the brain.
“Marijuana is the ideal compound to screw up everything for a kid,” says Hans Breiter, a professor of psychiatry and behavioral sciences at Northwestern University’s Feinberg School of Medicine, and a senior author of the study. “If you’re an athlete, a chess player, a debater or an artist, you need working memory, and marijuana hurts the brain circuitry.”
Breiter, who himself has four children 11 to 21, adds: “The more I study marijuana, the more I wonder if we should have legislation banning the use of it for everyone under 30.”
Read more: Pot Legalization: Why It's Still a Big Deal If Your Teen Smokes Pot