Cumulative and recent psychiatric symptoms as predictors of substance use onset: Does timing matter?

Aims: We examined two questions about the relationship between conduct disorder (CD), depression and anxiety symptoms and substance use onset: (i) what is the relative influence of recent and more chronic psychiatric symptoms on alcohol and marijuana use initiation and (ii) are there sensitive developmental periods when psychiatric symptoms have a stronger influence on substance use initiation? Design: Secondary analysis of longitudinal data from the Pittsburgh Youth Study, a cohort study of boys followed annually from 7 to 19 years of age. Setting: Recruitment occurred in public schools in Pittsburgh, Pennsylvania, USA. Participants: A total of 503 boys. Measurements: The primary outcomes were age of alcohol and marijuana use onset. Discrete-time hazard models were used to determine whether (i) recent (prior year); and (ii) cumulative (from age 7 until 2 years prior to substance use onset) psychiatric symptoms were associated with substance use onset. Findings: Recent anxiety symptoms [hazard ratio (HR)=1.10, 95% confidence interval (CI)=1.03-1.17], recent (HR=1.59, 95% CI=1.35-1.87), cumulative (HR=1.45, 95% CI=1.03-2.03) CD symptoms, and cumulative depression symptoms (HR=1.04, 95% CI=1.01-1.08) were associated with earlier alcohol use onset. Recent (HR=1.39, 95% CI=1.22-1.58) and cumulative CD symptoms (HR=1.38, 95% CI=1.02-1.85) were associated with marijuana use onset. Recent anxiety symptoms were only associated with alcohol use onset among black participants. Conclusions: Timing matters in the relationship between psychiatric symptoms and substance use onset in childhood and adolescence, and the psychiatric predictors of onset are substance-specific. There is no single sensitive developmental period for the influence of psychiatric symptoms on alcohol and marijuana use initiation.