Aims: The association between depression and substance dependence is poorly understood; examinations of these two disorders over time during key developmental periods can provide insight into how these problems relate to each other. The goal of the present study was to examine longitudinal associations between depression and substance (alcohol and illicit drug) dependence during the period from adolescence through early adulthood.
Participants: Participants in the Minnesota Twin Family Study, a community-based sample of 1252 youth and their families, were used. Youth were first assessed at age 17; they returned to the study at ages 20 and 24.
Measurements: Major depression and drug and alcohol dependence were assessed via structured interviews. Gender was examined as a possible moderator.
Findings: The results indicated that both substance dependence and depression showed stability over time--that is, each disorder was associated with increased risk for the same disorder later. Substance dependence between ages 17 and 20 predicted increased risk of depression between ages 20 and 24. These associations did not differ significantly by gender.
Conclusions: Substance dependence during late adolescence predicts the subsequent occurrence of major depression.
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