A new study has found that teenagers who begin using cannabis before age 15 face significantly greater health risks later in life compared with peers who abstain or begin use later. The research, based on data from the long-term Québec Longitudinal Study of Child Development, tracked more than 1,500 participants from childhood into young adulthood.
According to the findings, about 20 per cent of the study group reported using cannabis by age 15, and by age 17 they were using it monthly or more often. Those early and frequent users were much more likely in young adulthood to seek healthcare for mental and physical health conditions. Specifically, they had a 51 per cent higher risk of needing care for mental-health problems, and an 86 per cent higher risk of physical-health problems compared to teens who did not use cannabis in early adolescence.
Experts say the new study helps clarify why early cannabis use is problematic. The adolescent brain continues to develop well into young adulthood, particularly in areas that govern thinking, decision-making and emotional regulation. Regular cannabis use in this sensitive period may “interrupt” healthy development, leading to poorer outcomes.
One of the study authors, psychologist Massimiliano Orri of McGill University, said the risk was especially high in the group that started early and continued regular use of the “early and frequent” users. The study controlled for many confounding factors, including bullying, family environment and peer relationships, strengthening the evidence that early cannabis use itself poses risk.
Physical-health issues reported among the early users included more respiratory problems, injuries and accidents likely tied to intoxication or withdrawal effects.
Health professionals say the message is clear: avoiding early cannabis use until the brain is fully developed may reduce the risk of these adverse outcomes. For parents, educators and policy makers, the findings underscore the importance of prevention efforts aimed at younger teens.
