Mental Health

Marijuana Or Alcohol, What's Worse? Weed Harms Teen Brains More, Study Suggests

With the increasing legalization of marijuana use for adults, there also comes an increased risk of teenagers giving it a try. While research is still trying to narrow down the exact effects of the drug on the brain, many have indicated a risk of impaired cognition in younger individuals. 

In their new findings, researchers at the University of Montreal, Canada, suggested these negative consequences may be long-lasting and even worse than those of alcohol consumption.

The study titled "A Population-Based Analysis of the Relationship Between Substance Use and Adolescent Cognitive Development" was published in the American Journal of Psychiatry on Oct. 3.

The research team recruited nearly 4,000 teenagers from over thirty different Canadian schools to track them for a period of four years. At the start of the study, the teens were in seventh grade i.e. around 13 years old.

On an annual basis, each participant was asked to rate if and how often they used marijuana and drank alcohol. The team gave their word the details would not be shared with parents unless there was a risk of harm. Participants were also instructed to take computer-based cognitive tests which measured their recall memory, perceptual reasoning, inhibitory control, and short-term memory.

Overall, teens who used cannabis and drank alcohol were more likely to fare poorly on all domains of the cognitive test. It was noted an increase in marijuana use, unlike alcohol consumption, showed "additional concurrent and lagged effects" on functions like memory. Cognition did not show improvement even after students reported stopping the use of cannabis.

"This study focuses on the neuropsychological effects of cannabis. We think it’s important because it is linked to how someone functions in life," said lead author Patricia Conrad, a professor of psychiatry at Montreal.

"Cannabis causes cognitive impairment and delayed cognitive development in adolescents. Our study showed that early marijuana use has a lasting effect on cognitive ability," she added.

Diving into lasting effects, one association Conrad found particularly concerning was between cannabis use and inhibitory control. Lower performance in this domain is believed to be a risk factor for other addictive behaviors. Conrad said this might explain why cannabis use, in some cases, has the potential to become a gateway drug for other addictions. 

"We also want to identify if these effects on brain development are related to other difficulties such as poor academic performance, neuroanatomical damage, and the risk of future addiction or mental health disorders," said co-author Jean-François G. Morin, a Ph.D. student at Montreal.

In a 2017 report by the American Academy of Pediatrics, experts emphasized against the use of marijuana by children and teenagers since their brains are still developing and highly vulnerable.

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