Early Substance Use and Later Depressive Symptoms Among Canadian Adolescents: Examining the Association Using Intersectionality Theory
BACKGROUND: Growing evidence suggests adolescent substance use may lead to depression and earlier initiation may be especially problematic. Social identities or positions defined by such factors as gender, race, or socioeconomic status (SES), have been associated with adolescent substance use and depression; however, their effects have primarily been examined independently, whereas Intersectionality Theory emphasizes the potential synergistic effects of multiple aspects of individual identity. OBJECTIVES: First, to describe early substance users (<14 years) in Canada while considering intersecting social positions by gender, race, and SES; second, to examine the association between early substance use and depressive symptoms later in adolescence; and third, to investigate differences in this relationship at varying intersections of gender, race, and SES. METHODS: Data were from the 2017/2018 Canadian Health Behaviour in School-aged Children study, providing a nationally representative sample of adolescents in grades 9 and 10. Descriptive and multilevel, multivariable modified Poisson regression analyses were performed to estimate the relative risks for the association between early substance use and later depressive symptoms. Multiplicative interaction and stratification by two- and three-way combinations of gender, race, and SES were used to assess effect modification. RESULTS: Nearly one in four (23.5%) adolescents reported early substance use, and this proportion differed significantly across subgroups at intersecting social positions, with subgroups that included lower SES generally displaying a greater proportion of reported early substance use. The risk of depressive symptoms was significantly higher among those who reported early substance use compared to those who did not (RR 1.23; 95% CI 1.16-1.31). Combinations of gender, race and SES were not found to modify the relationship between early substance use and depressive symptoms; post hoc power calculations indicated that there was insufficient power to detect interacting effects between intersecting social positions and early substance use in predicting later depressive symptoms. CONCLUSION: Preventing substance use in early adolescence, such as by delaying substance use initiation, may help prevent depression overall in youth. As the proportion of reported early substance users differed by subgroups of intersecting social positions, interventions aimed at preventing early substance use should use a targeted, intersectional approach.