Teenagers who smoke marijuana daily are over 60 percent less likely to complete high school than those who never use. They're also 60 percent less likely to graduate college and seven times more likely to attempt suicide. Those are the startling conclusions of a new study of adolescent marijuana use published in The Lancet Psychiatry, a British journal of health research.
Researchers gathered data on the frequency of marijuana use among 3,725 students from Australia and New Zealand, and then looked at the students' developmental outcomes up to the age of 30. They found "clear and consistent associations between frequency of cannabis use during adolescence and most young adult outcomes investigated, even after controlling for 53 potential confounding factors including age, sex, ethnicity, socioeconomic status, use of other drugs, and mental illness."
Significantly, they found that the risks for negative outcomes increased with the frequency of marijuana use. Study co-author Edmund Sillins said that the relationship between marijuana use and negative outcomes is significant even at low levels of use (e.g., less than monthly), and that "the results suggest that there may not be a threshold where use can be deemed safe" for teens.
According to the study, there are significant relationships between marijuana use and high school graduation, college graduation, suicide attempts, marijuana dependency (not wholly surprising), and other illicit drug use.