Teens who start using cannabis before age 15 are significantly more likely to experience both mental and physical health problems in young adulthood, according to new research published this week in JAMA Network Open.
The study, conducted by researchers at McGill University and based on data from the Québec Longitudinal Study of Child Development, followed more than 1,500 participants from birth through young adulthood. It found that those who began using cannabis early and continued frequently were far more likely to need medical care later for mental or physical health conditions compared to peers who either started later or abstained altogether.
“The risk is concentrated among those who start early and use frequently,” said the study’s lead author, psychologist Massimiliano Orri of McGill University.
Among the teens studied, 60% reported no cannabis use during adolescence. Of the remaining 40%, half began experimenting in their later teen years and used the drug infrequently. But those who began before age 15—roughly 20% of participants—used cannabis at least monthly by age 17 and were 51% more likely to seek treatment for mental health issues and 86% more likely to seek help for physical health problems, even after controlling for factors like family environment, bullying, and social relationships.
Researchers found that early users were especially prone to respiratory issues, accidents, and unintentional injuries. These outcomes, they wrote, may stem from both intoxication and withdrawal effects.
“This further builds the case that cannabis use in adolescence adversely affects the health trajectories of those who use it,” said Dr. Ryan Sultan, a Columbia University psychiatrist not involved in the study.
Psychologist Krista Lisdahl of the University of Wisconsin-Milwaukee, who studies adolescent brain development, called the findings “alarming,” adding that regular cannabis use may disrupt brain maturation in areas responsible for emotion regulation and decision-making.
Experts like Sultan emphasize delaying cannabis use until at least age 25 to minimize risks. “The adolescent brain is still developing,” he said. “Using cannabis early can interfere with that process and increase the likelihood of long-term health and behavioral issues.”
Read the whole article from NPR here.
