A study on teenagers suggests that marijuana is worse than alcohol for the brain

WAlthough the recreational use of marijuana is an increasingly legalized activity, the exact science of what the drug does to the brain is not yet conclusive. In an effort to understand what happens to the brain early in the smoking season, scientists have recently studied the use of psychoactive substances in nearly 4,000 adolescents in Canada. Their research indicates that marijuana not only affects the cognitive abilities of adolescents, but also has more long-term effects on working memory than alcohol.

In the study, published Wednesday in the American Journal of PsychiatryScientists at CHU Sainte-Justine and the Université de Montréal have determined that when adolescents consume more and more marijuana, cognitive functions such as recall memory inhibition and working memory are damaged. Both alcohol and marijuana influence the brain functioning of teenagers, Patricia Conrod, lead author, Ph.D., Wednesday, "The increase in cannabis use, but not the consumption of cannabis." alcohol, had simultaneous and delayed effects on cognitive functions. "

For the study, Conrod and his team evaluated 3,826 seventh grade students in 31 schools in the Montreal metropolitan area for four years. Once a year, researchers asked students to rate the frequency of their marijuana and alcohol use on a six-point scale. Students were assured that parents and teachers would not have access to information unless their habits indicate an imminent risk of harm.

Then, cognitive functions of adolescents were evaluated using various memory tests. For example, a delayed recall test involved reproducing a previously learned stimulus pattern 30 minutes later. In a perceptual reasoning test, teens were asked to perform a series of increasingly difficult puzzles, and in an inhibitory control test, they had to learn by trial and error when to respond to "good" or "Bad" numbers.

These tests, combined with reports on adolescent substance use, found that people who used cannabis and alcohol were more likely to have working memory, perceptual reasoning and worse inhibitory control. The results are in line with previous research, but the new part of the study is the revelation that cannabis could be worse for brain growth.

"Beyond the effect of predisposing to cannabis use during adolescence, when increases in the frequency of cannabis use were observed during a given year, reductions in memory with delayed recall and perceptual reasoning were observed the same year. These effects were independent of any changes in the amount and frequency of alcohol, write the authors.

This conclusion differs from previous research that addressed a much debated question: what is worse for your brain, your marijuana or your alcohol? A study conducted in 2017 by the University of Colorado at Boulder came to the opposite conclusion, suggesting that alcohol consumption is more damaging to the brain than cannabis. When these scientists examined the brains of 850 adults and 430 adolescents, they discovered that alcohol led to a reduction in gray and white matter, essential tissues that affect brain function. Smoking marijuana did not result in the same losses.

However, the National Institute for Combating Drug Abuse maintains his position that "substantial evidence from animal research and a growing number of studies in humans indicate that exposure to marijuana during development can cause long-term, even permanent, changes in the brain ". Other studies are needed, especially those that will continue to follow. adolescents, because they have easier access to substances in college – to know their effects on cognitive functions. Until then, it can be said that smoking marijuana has cognitive consequences.