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Young people who use marijuana weekly have double the risk of this mental illness later in life
What is Depression? (and Schizophrenia)
Heavy Marijuana users are more likely than non-users to be diagnosed with schizophrenia later in life. A recent study found that people who had used marijuana more than 50 times before the age of 18, had a threefold increased risk of developing schizophrenia later in life.
Source: Zammit, S et al., "Self-reported cannabis use as a risk factor for schizophrenia in Swedish conscripts of 1969: historical cohort study," British Medical Journal, 325:1199-1201, 2002 Arseneault L, et al., "Cannabis use in adolescence and risk for adult psychosis: longitudinal prospective study," British Medical Journal, 325:1212-1213, 2002
Source: Patton, GC et al. "Cannabis use and mental health in young people: cohort study." British Medical Journal, 325: 1195�1198, 2002