Youth Who Use Cannabis at Early Age More Likely to Have Health Problems as Adults, McGill Study Finds

Using marijuana before age 15 is linked to more physical and psychological problems in early adulthood, a McGill University study says. Roxana Gonzalez/Shutterstock10/29/2025|Updated: 10/29/2025Youth who start using marijuana before the age of 15 have more physical and psychological problems into early adulthood, according to a study by McGill University researchers.The study used data from the Quebec Longitudinal Study of Child Development, with researchers looking at cannabis use in 1,591 individuals between 12 and 17 years old, as well as health-care records up to age 23.Chandra Philip is a news reporter with the Canadian edition of The Epoch Times. Author’s Selected Articles