Internalizing disorders and substance use disorders in youth: Comorbidity, risk, temporal order, and implications for intervention

This review examines the empirical literature on the relationship between internalizing disorders and substance use disorders (SUDs) in youth in terms of (a) comorbidity rates, (b) risk relationships, (c) temporal sequencing, and (d) implications for intervention. Findings from community and clinical samples suggest that comorbidity rates range from 9.0 to 47.9%. The majority of the evidence supports the temporal precedence of internalizing disorders before substance use disorders and a unidirectional risk model in which internalizing disorders increase risk for later substance use disorders. Implications of this relationship for interventions are considered, both in terms of treatment outcome for principal disorders and in terms of the potential “secondary benefit” of treating one disorder for preventing or reducing risk of the other. Finally, recommendations for future research on the relationship between internalizing disorders and SUDs in youth are discussed.

Research highlights
► Internalizing disorders and substance use disorders are frequently comorbid in youth.
► Evidence suggests internalizing disorders temporally precede substance use disorders.
► Internalizing disorders increase risk for later substance use disorders.
► Findings have important implications for interventions.