Abstract
BACKGROUND: There is controversy about whether psychotherapies are effective in the treatment of subclinical depression, defined by clinically relevant depressive symptoms in the absence of a major depressive disorder. AIMS: To examine whether psychotherapies are effective in reducing depressive symptoms, reduce the risk of developing major depressive disorder and have comparable effects to psychological treatment of major depression. METHOD: We conducted a meta-analysis of 18 studies comparing a psychological treatment of subclinical depression with a control group. RESULTS: The target groups, therapies and characteristics of the included studies differed considerably from each other, and the quality of many studies was not optimal. Psychotherapies did have a small to moderate effect on depressive symptoms against care as usual at the post-test assessment (g = 0.35, 95% CI 0.23-0.47; NNT = 5, 95% CI 4-8) and significantly reduced the incidence of major depressive episodes at 6 months (RR = 0.61) and possibly at 12 months (RR = 0.74). The effects were significantly smaller than those of psychotherapy for major depressive disorder and could be accounted for by non-specific effects of treatment. CONCLUSIONS: Psychotherapy may be effective in the treatment of subclinical depression and reduce the incidence of major depression, but more high-quality research is needed.