Does Early Onset Marijuana Use Increase the Risk of Young Adult Anxiety and Depression in Urban Youth? Evidence from a Baltimore City Cohort

Background: Substance use and internalizing conditions are highly comorbid; however, the direction of the relationship is unclear. There is well-established evidence that those who experience anxiety and depression often self-medicate with various substances, such as marijuana. What is less clear is whether marijuana use in particular also increases the risk for anxiety and depression among those who use marijuana but do not have a history of depression or anxiety. Theorists have suggested that those who use marijuana early in the life course fail to develop appropriate coping skills to deal with life’s adversity. Youth in urban areas may be particularly at risk for using marijuana given greater adversities and stressors these youth may experience and a high prevalence of marijuana in these settings. This study examines whether those who begin to use marijuana during early adolescence are more vulnerable to depression and/or anxiety in adulthood compared to those who initiate later in life or not at all.

Methods: This study uses data from a cohort study of Baltimore youth (89% Black, 70% low SES) who were part of a preventive intervention in first grade and followed annually through age 26. Adjusted logistic regression analyses examine the potential impact of early onset marijuana use (before age 15) compared to later onset and to non-users on the development of major depression and generalized anxiety disorder in adulthood (ages 19-26), measured by the DISC. Models control for race, socioeconomic status, gender, intervention status, earlier depressive symptoms, anxious mood, aggressive behavior, neighborhood disadvantage, community violence, and alcohol and tobacco use.

Results: Rates of major depressive disorder or generalized anxiety disorder are highest among those who initiated marijuana before age 15 (14.9%), compared to those who initiated at age 15 or older (8.2%) and those who did not use marijuana (1.5%). After adjusting for confounders, youth who began marijuana use in early adolescence (before age 15) are significantly more likely than those who initiated later (ages 15+, aOR=2.9, p=.009) and those who did not use at all (aOR=22.7, p=.004) to meet criteria for past year major depressive disorder and/or generalized anxiety disorder in young adulthood.

Conclusion: Results suggest that early onset marijuana use may make an individual more vulnerable to the development of depression and anxiety, potentially because early marijuana users may not develop appropriate coping skills for dealing with stressors. Future research should directly test this mechanism and consider intervening with marijuana users early in adolescence to facilitate the development of coping skills that may reduce later internalizing problems and negative sequelae.