According to new analysis of previous research, learning and memory problems caused by marijuana consumption could last for weeks, even when the user is not high.
Researchers from the University of Montreal found that many of the known learning and memory difficulty from marijuana use among young people, could linger for weeks. This includes a slow processing speed, and difficulties in focusing.
Verbal learning, retention and recall were especially affected for longer periods when the person was no longer high.
Marijuana taps into existing brain systems that use endocannabinoids, cannabis-like substances that occur naturally in the body, explained Dr. Sharon Levy, director of the Adolescent Substance Use and Addiction Program at Boston Children’s Hospital.
“When you consume cannabis you’re really flooding the system with the psychoactive plant chemical THC (tetrahydrocannabinol), which in the short term is really great at hijacking the brain’s reward system.”
“The problem here is that you can’t do a randomized, controlled trial of 100 kids where 50 are told to smoke cannabis and 50 are told not to,” Levy said.
In adolescence the brain is especially vulnerable, remarked Staci Gruber, director of the Cognitive and Clinical Neuroimaging Core and the Marijuana Investigations for Neuroscientific Discovery (MIND) at McLean Hospital. “Almost anything can change the trajectory of brain development,” added Gruber, who is also an associate professor of psychiatry at Harvard Medical School. “If you can protect your brain from everything, not just cannabis, it’s best for the brain. What parents should be saying is not ‘just say no’ but rather ‘just not yet.’”
As for the question of whether or not marijuana today may be the cause, Carrie Cuttler, an assistant professor in the department of psychology and director of the Health and Cognition lab at Washington State University has said, “The cannabis of today is very different. Back then cannabis had maybe 3 percent THC, now we’re seeing as much as 90 percent in some samples.”
