Effects of independent and substance-induced major depressive disorder on remission and relapse of alcohol, cocaine and heroin dependence.

Aims: Little is known about the differential effects of independent and substance-induced major depression on the longitudinal course of alcohol, cocaine and heroin disorders when studied prospectively.

Design: Consecutively admitted in-patients, evaluated at baseline, 6-, 12- and 18-month follow-ups.

Setting: Baseline evaluations in a short-stay in-patient urban community psychiatric hospital unit.

Participants: Adults (n = 250) with current DSM-IV cocaine, heroin and/or alcohol dependence at baseline.

Measurements: The Psychiatric Research Interview for Substance and Mental Disorders (PRISM), used to evaluate independent and substance-induced major depression, alcohol, cocaine and heroin dependence, and other psychiatric disorders. Outcomes for each substance: (i) time (weeks) from hospital discharge to first use; (ii) time from discharge to onset of sustained (≥26 weeks) remission from dependence; (iii) time from onset of sustained remission to relapse.

Findings: Substance-induced major depression significantly predicted post-discharge use of alcohol, cocaine and heroin (hazard ratios 4.7, 5.3 and 6.5, respectively). Among patients achieving stable remissions from dependence, independent major depression predicted relapse to alcohol and cocaine dependence (hazard ratios 2.3 and 2.7, respectively).

Conclusions: Substance-induced and independent major depressions were both related to post-discharge use of alcohol, cocaine and heroin. The findings suggest the importance of clinical attention to both types of depression in substance abusing patients.