The temporal dynamics of relationships between cannabis, psychosis and depression among young adults with psychotic disorders: findings from a 10-month prospective study.
Psychological Medicine July 1, 2007 Louisa Degenhardt, Chris Tennant, Stuart Gilmour et al.
Over 10 months, 101 patients with schizophrenia and related disorders were assessed monthly for cannabis use, medication compliance, and symptoms of psychosis and depression. Cannabis use predicted a small but statistically significant increase in psychotic symptoms, but not depressive symptoms, after controlling for other variables. Symptoms of depression and psychosis did not predict cannabis use. Continued cannabis use by persons with schizophrenia predicts a small increase in psychotic symptom severity, but not vice versa.