Effects of exercise training on cognition in adults with depression: A systematic review and three-level meta-analysis

Background: Cognitive impairment is a central feature of depression. Exercise training has enormous potential as a nonpharmacological intervention to improve cognition in depressed individuals. Objective: This review aimed to evaluate and update the effect of exercise training on overall cognition and its subdomains, as well as whether moderators influence the effect of exercise training on cognition in depressed adults. Design: Systematic review and three-level meta-analysis of randomized controlled trials. Methods: We systematically searched Embase, Ovid MEDLINE, Web of Science, PubMed, and Scopus from their inception to February 14, 2024, and updated the search results on December 5, 2024. Randomized controlled trials investigating how exercise training affected cognition in depressed adults were included. The meta-analysis was performed using a random-effects model in R. We used the Physiotherapy Evidence Database scale to evaluate the study's quality. Results: Twenty-two studies were included. Exercise training showed statistically significant improvements in overall cognition [g = 0.21; 95 % confidence interval (CI) = 0.12, 0.30] and cognitive subdomains of processing speed (g = 0.20; 95 % CI = 0.04, 0.36), attention (g = 0.21; 95 % CI = 0.06, 0.35), memory (g = 0.24; 95 % CI = 0.11, 0.38), and executive function (g = 0.21; 95 % CI = 0.09, 0.33) compared with comparison groups in depressed adults. The greater cognitive benefits were observed when participants exercised twice a week (g = 0.30; 95 % CI = 0.03, 0.56), at a low intensity (g = 0.26; 95 % CI = 0.08, 0.43), spent more than 60 min per session (g = 0.24; 95 % CI = 0.05, 0.44), 150 min or more per week (g = 0.27; 95 % CI = 0.09, 0.45), had a program duration more than 10 weeks (g = 0.25; 95 % CI = 0.12, 0.39), and engaged in mind–body exercise (g = 0.26; 95 % CI = 0.08, 0.43). The clinical setting, sample size, and comparison group for memory moderated the effects of exercise training on cognition. Conclusions: Exercise training is an effective nonpharmacological intervention that enhances overall cognition and subdomains of processing speed, attention, memory, and executive function compared with comparison groups in depressed adults. This study only included English-language articles, which may have caused a language bias, and Egger's test revealed a possibility of publication bias. Registration number: CRD42023457900 (PROSPERO). Tweetable abstract: Exercise training is an effective nonpharmacological intervention for adults with depression to improve overall cognition and cognitive subdomains of processing speed, attention, memory, and executive function compared with comparison groups.