Among patients with substance dependence and comorbid major depressive disorder (MDD) receiving treatment in a controlled trial, we examined if group differences in depression were mediated by 12-step involvement, and if the effects of 12-Step involvement on future alcohol and drug use were mediated by reductions in depression.
Controlled trial of Twelve-Step Facilitation (TSF) and Integrated Cognitive Behavioral Therapy (ICBT), delivered in outpatient groups for 6 months with adjunct pharmacotherapy.
Outpatient dual diagnosis clinic in Veteran’s Affairs Healthcare Center.
Veterans (N = 209) diagnosed with alcohol, stimulant, or marijuana dependence and substance-independent MDD.
Twelve-step attendance and affiliation, depression severity, percent days drinking, and percent days using drugs assessed at baseline and Months 3, 6, and 9.
In multilevel analyses greater 12-step meeting attendance predicted lower depression and mediated the superior depression outcomes of the TSF group, explaining 24.3% of the group difference in depression. Independent of treatment group, lower depression severity predicted lower future alcohol use and mediated the effects of 12-step meetings, explaining 15.7% of their effects on future drinking. Controlled, lagged models indicated these effects were not confounded by current substance use, suggesting that depression had unique associations with 12-step meeting attendance and future drinking.
For patients with substance dependence and MDD, attendance at 12-step meetings is associated with mental health benefits that extend beyond substance use, and reduced depression could be a key mechanism whereby 12-step meetings reduce future drinking in this population.