Cannabis might be legal, but is it safe? That might depend on age, genetics and frequency of use

Marijuana is legal in 24 states, three U.S. territories and Washington D.C., so many assume it's harmless. And for some it might be. But a new study shows that those with cannabis use disorder (or an inability to stop using it despite health or social consequences) are three times more likely to die in the next five years than those without the disorder. A second study shows that those with the disorder are also more likely to develop schizophrenia than others.

Dr. Daniel Myran is a professor of family medicine at the University of Ottawa and an author on both studies. He explains how the studies were conducted and how to interpret the results.