The increase in cannabis use and cannabis use disorder (CUD) among young adults in the U.S, along with the concurrent rise in mental health issues such as depression, has emerged as a significant public health concern. Previous research indicates that depression and cannabis use may share overlapping risk factors and frequently co-occur; however, some findings have shown varying results. These discrepancies may arise from studies focusing predominantly on adolescents with limited cannabis access or relying on single-time-point assessments, which fail to capture the long-term effects of depressive symptoms. Consequently, the current study aims to systematically investigate the relationship between the cumulative experience of depressive symptoms from ages 19 to 23 and the likelihood of developing CUD by age 26. Additionally, it will explore how this relationship is influenced by individuals’ perceptions of cannabis accessibility and the associated risks.
The study surveyed 4,407 young adults participating in the Community Youth Development Study at ages 19, 21, and 23, collecting behavioral and psychosocial data. Depressive symptoms were assessed using the 9-item Patient Health Questionnaire (PHQ-9) at each wave, with the cumulative depressive experience calculated as the sum of instances where participants scored 10 or above. Cannabis use disorder (CUD) was evaluated via diagnostic interviews based on DSM-IV criteria. Additionally, participants self-reported perceived ease of access to cannabis and the anticipated harm associated with regular use. The collected data were analyzed using marginal structural modeling with inverse probability weighting, adjusting for both time-fixed and time-varying covariates, to examine the association between cumulative depressive symptoms and CUD at age 26, while also assessing the moderating effects of perceived cannabis access and harm.
The study found that cumulative depressive symptoms, measured over three survey waves from ages 19 to 23, were significantly associated with an increased risk of cannabis use disorder (CUD) at age 26. Specifically, each one-unit increase in cumulative depressive symptoms was associated with a 46% increase in the likelihood of developing CUD at age 26, after adjusting for prior cannabis and other substance use, depressive symptoms, and various time-fixed and time-varying covariates. Although the moderating effects of perceived ease of cannabis access and perceived harm were not statistically significant, the association appeared somewhat attenuated among individuals with lower perceived harm. Moreover, post hoc analyses revealed that among young adults reporting cannabis use at age 26, cumulative depressive symptoms were linked to an increased likelihood of using cannabis to alleviate anxiety or depression, which in turn was associated with a higher risk of CUD. These findings suggest that persistent depressive symptoms may promote cannabis use as a means of emotion regulation, ultimately increasing the risk for CUD.
Takeaway: Persistent depressive symptoms from ages 19 to 23 significantly increase the risk of developing cannabis use disorder at age 26, suggesting that enduring depression may drive cannabis use as a coping mechanism.