The health impacts of marijuana are currently the subject of significant public debate. Past data have suggested a link to numerous mental health outcomes including substance use disorders (SUDs), mood disorders, and anxiety, although whether marijuana use actually causes these conditions, or just shares common contributing factors, has been difficult to specify. A new study used data on nearly 35,000 participants in two waves (2001-2002 and 2004-2005) of the longitudinal National Epidemiological Survey on Alcohol and Related Conditions, to prospectively examine associations between marijuana use and various mental health outcomes. Like earlier studies, unadjusted analyses of the data found marijuana use to be associated with a wide range of psychiatric disorders; but after adjusting for common underlying factors that predict marijuana use (such as age and other sociodemographic characteristics), the only associations with marijuana use that remained significant across all analyses were SUDs—including alcohol use, nicotine dependence, cannabis use disorder, and other drug use disorders.
- Blanco C, Hasin DS, Wall MM, et al. Cannabis Use and Risk of Psychiatric Disorders: Prospective Evidence From a US National Longitudinal Study. JAMA Psychiatry. doi:10.1001/jamapsychiatry.2015.3229.