Directions of the relationship between substance use and depressive symptoms from adolescence to young adulthood
Because both depression and substance use are prevalent among adolescents and are often comorbid, researchers explored the longitudinal relationship between the two from adolescence into young adulthood. A total of 12,288 adolescents in grades 7-12 were sampled in 1994 and were interviewed in waves until 2009. The Center for Epidemiologic Studies Depression scale (CES-D) was used at each interview wave to capture depressive symptoms and frequency. Substance use and frequency of alcohol binge drinking, cigarettes, and marijuana were also assessed at each interview. Increases on the CES-D predicted an average increase in male monthly marijuana use by 1 day, and an increase in monthly cigarette smoking frequency by 2 days for females. In other words, depressive symptoms were associated with later increases in smoking frequency for females and marijuana use frequency for males. Smoking was also associated with later increases in depressive symptoms for both males and females. These findings support the self-medication hypothesis that individuals are self-medicating depressive symptoms with the use of marijuana and cigarettes. However, there is also a reverse pathway that indicates an increase in smoking frequency is significantly associated with later increases in depressive symptoms among both genders. Interestingly, this study found no evidence supporting the idea that individuals self-medicated with binge drinking, which could be a function of the measures used.
Take away: The findings of this study indicate a bidirectional relationship between depressive symptoms and substance use among adolescents. This research shows that screening for both depression and substance use in this population is important. Interventions and prevention strategies involving depression could benefit from having a substance use component, and vice versa.
Wilkinson, A.L., Halpern, C.T., & Herring, A.H. (2016) Directions of the relationship between substance use and depressive symptoms from adolescence to young adulthood. Addictive Behaviors, 60, 64-70.