Moderators of fluoxetine treatment response for children and adolescents with comorbid depression and substance use disorders.

Our recent 8-week, randomized, placebo-controlled trial of fluoxetine in adolescents (ages 12-17 years) with comorbid depression and substance use disorder (SUD) did not detect a significant antidepressant treatment effect. The purpose of this secondary analysis was to explore moderators of the effect of fluoxetine in this sample. Static moderators measured at baseline were depression chronicity and hopelessness severity; time-varying moderators measured at baseline and weekly during the 8-week trial period were alcohol and marijuana use severity. Treatment effects on depression outcomes were examined among moderating subgroups in random effects regression models. Subjects assigned to fluoxetine treatment with chronic depression at baseline (p = .04) or no more than moderate alcohol use during the trial (p = .04) showed significantly greater decline in depression symptoms in comparison to placebo-assigned subgroups. The current analysis suggests that youth with chronic depression and no more than moderate alcohol consumption are likely to respond better to treatment with fluoxetine compared with placebo than youth with transient depression and heavy alcohol use.