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.