Cognitive-behavioral therapy for depression in bipolar disorder: a meta-analysis.

Given the prevalence of null hypothesis significance testing, cognitive-behavioral therapy's effect on depressive symptoms of bipolar disorder is not fully understood in the absence of effect size statistics. The present study discusses the disadvantages associated with null hypothesis significance testing and seeks to overcome these shortcomings via conducting a meta-analysis which examines cognitive-behavioral therapy for depressive symptoms in persons with bipolar disorder. A systematic literature search was conducted and included articles were subject to meta-analytic procedures. With a mean weighted Cohen's d of -0.29, relative to treatment as usual, cognitive-behavioral therapy has a small effect on depressive symptoms in persons with bipolar disorder. The strengths, limitations, and need for future research are discussed.