James A. Foulds, Simon J. Adamson, Joseph M. Boden, Jonathan A. Williman, Roger T. Mulder

In patients with an alcohol use disorder, depression is commonly categorised as independent (ID) or substance-induced (SID). It is not established whether these conditions respond differently to treatment. MEDLINE, Embase and Cochrane databases from 1980 to 2014 were searched for studies on alcohol use disorders with coexisting depressive symptoms. Meta-analyses were conducted using random effects models, to derive pooled effect estimates of the change in depression during treatment and the effect of antidepressant therapy. Twenty-two studies met inclusion criteria for the review, of which 11/22 were included in the meta-analysis. All studies reported a large improvement in depression symptom score, most of which occurred within the first 3-6 weeks of treatment. The amount of improvement during follow up was similar in studies on ID in comparison to those in undifferentiated depression. Evidence on the outcome for SID was limited. The effect size of antidepressant therapy compared to placebo was 0.25 (0.06, 0.44) for ID and 0.08 (-0.31, 0.47) for SID or undifferentiated depression. Few studies examined the natural history and treatment response of SID. There was heterogeneity between studies, which was partly explained by baseline depression severity. Treatment for depression co-occurring with an alcohol use disorder is associated with a large early improvement in depression, even if depression is believed to be independent of drinking. The effect of antidepressant therapy on depression in patients with alcohol use disorders is modest, with stronger evidence in ID.