A systematic review of cognitive effects of exercise in depression

OBJECTIVE: The aim of the present systematic review and meta-analysis was to evaluate the impact of physical exercise on cognitive symptoms in depressed adult patients. METHODS: Systematic literature search was performed in Web of Science™ and CINAHL from inception to August 2016. Two reviewers independently selected randomized trials evaluating the effect of exercise on cognitive functions in patients with a validated diagnosis of depression. Outcome measures included global cognition and different cognitive domains (speed of processing, attention/vigilance, working memory, verbal and visual memory, and reasoning). RESULTS: Eight trials met inclusion criteria (637 patients). A fixed-effects model showed absence of beneficial effect on global cognition (Hedges' g = 0.07, 95% CI -0.08 to 0.24, I2 = 0%) as well as on specific cognitive domains. Sensitivity analyses did not show an impact of exercise in studies with shorter intervention duration compared to longer trials (between group heterogeneity Q = 3.564, df = 1, P = 0.059), single session per week compared to multiple sessions (Q = 2.691, df = 1, P = 0.101) and low exercise intensity compared with moderate/high intensity (Q = 2.952, df = 1, P = 0.086). CONCLUSION: Our meta-analysis did not observe a substantial benefit of physical exercise on cognitive symptoms in depression.