Background: The number of randomized, controlled studies of cognitive remediation (CR) for mood disorders (major depressive disorder [MDD] and bipolar illness [BD]), has grown substantially over the past 10 years. The role of study quality, participant characteristics, and intervention features in CR treatment effects remains largely unknown.
Methods: Electronic databases were searched up to February 2022 using variants of the key words: "cognitive remediation", "clinical trials", "major depressive disorder" and "bipolar disorder". This search produced 22 unique randomized, controlled trials that met all inclusion criteria for the study. Data were extracted by 3 authors with strong reliability (>90 %). Primary cognitive, and secondary symptom and functional outcomes were assessed with random effects models.
Results: The meta-analysis (993 participants) revealed that CR produced significant small-to-moderate size effects in attention, verbal learning and memory, working memory and executive function (Hedge's g = 0.29-0.45). CR produced a small-moderate effect on one secondary outcome: depressive symptoms (g = 0.33). CR programs that used an individualized approach produced larger effects on executive function. Samples with lower baseline IQ were more likely to benefit from CR on measures of working memory. Sample age, education, gender, or baseline depressive symptomatology did not serve as barriers to treatment gains, and observed effects were not epiphenomena of poorer design quality.
Limitations: The number of RCTs remains low.
Conclusions: CR produces small to moderate improvements in cognition and depressive symptoms in mood disorders. Future research should study how CR might be optimized to help generalize CR-related cognitive and symptom improvements to function.
Keywords: Bipolar illness; Clinical trial; Cognitive training; Major depressive disorder; Thinking skills.
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