Marijuana and your health: What 20 years of research reveals

Marijuana and your health: What 20 years of research reveals | Fox News
Critics argue that other variables besides marijuana use may be at work in the increased risk of mental health problems, and that it's possible that people with mental health problems are more likely to use marijuana to begin with, Hall wrote in the review.
However, other studies have since attempted to sort out the findings, he wrote, citing a 27-year follow-up of the Swedish cohort, in which researchers found "a dose–response relationship between frequency of cannabis use at age 18 and risk of schizophrenia during the whole follow-up period."
In the same study, the investigators estimated that 13 percent of schizophrenia cases diagnosed in the study "could be averted if all cannabis use had been prevented in the cohort," Hall reported.