The effects of major depressive disorder (MDD) on the course of substance dependence may differ depending on the temporal relationship of depression to dependence. We investigated the effects of MDD on the outcome of substance dependence under 3 circumstances: (1) lifetime onset of MDD prior to lifetime onset of dependence onset, (2) current MDD occurring during a period of abstinence, and (3) current MDD during substance use that exceeded the expected effects of intoxication or withdrawal.
A sample of 250 inpatients with DSM-IV cocaine, heroin, and/or alcohol dependence were followed up at 6, 12, and 18 months. The Psychiatric Research Interview for Substance and Mental Disorders (PRISM) was used to make DSM-IV diagnoses. Using Cox proportional hazards models, stable remissions (those lasting at least 26 weeks) from DSM-IV cocaine, heroin, and/or alcohol dependence and from use were studied, as well as subsequent relapses of dependence and use.
Patients with current substance-induced MDD were less likely to remit from dependence (adjusted hazards ratio, 0.11) than patients with no baseline MDD. A history of MDD prior to lifetime onset of substance dependence also reduced the likelihood of remission relative to the absence of such a history(adjusted hazard ratio, 0.49). Major depressive disorder during sustained abstinence predicted dependence relapse (adjusted hazards ratio, 3.07) and substance use after hospital discharge compared with those without abstinence MDD (adjusted hazards ratio, 1.45).
The timing of depressive episodes relative to substance dependence served as an important factor in the remission and relapse of substance dependence and substance use.