Teens who use weed before age 15 have more trouble later, a study finds

Teens who start using cannabis before age 15 are more likely to use the drug often later in their lives. They are also more likely to develop mental and physical health problems in young adulthood compared to their peers who did not use the drug in adolescence.

Those are the findings of a new study in JAMA Network Open .

"This further builds the case that cannabis use in adolescence adversely affects the [health] trajectories of those who use it," says psychiatrist Dr. Ryan Sultan at Columbia University, who wasn't involved in the new research.

The new study used data from the Québec Longitudinal Study of Child Development. Researchers in Montreal, Canada, have been following more than 1,500 kids since birth into young adulthood to understand the factors that influence their d