The Effect of Exercise in Clinically Depressed Adults: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Objective: To assess the effectiveness of exercise in adults with clinical depression.

Data Sources: The databases CINAHL, Embase, Cochrane Database of Systematic reviews, Cochrane Controlled Trials Register, MEDLINE, and PsycINFO were searched (1806-2008) using medical subject headings (MeSH) and text word terms depression, depressive disorder and exercise, aerobic, non-aerobic, physical activity, physical fitness, walk*, jog*, run*, bicycling, swim*, strength, and resistance.

Study Selection: Randomized trials including adults with clinical depression according to any diagnostic system were included.

Data Extraction: Two investigators evaluated trials using a prepiloted structured form.

Data Synthesis: Thirteen trials were identified that fulfilled the inclusion criteria. Eight had adequate allocation concealment, 6 had a blinded outcome, and 5 used intention-to-treat analyses. The pooled standardized mean difference (SMD) calculated using a random-effects model was −0.40 (95% CI, −0.66 to -0.14), with evidence of heterogeneity between trials (I2 = 57.2%, P = .005). There was an inverse association between duration of intervention and the magnitude of the association of exercise with depression (P = .002). No other characteristics were related to between-study heterogeneity. Pooled analysis of 5 trials with long-term follow-up (ie, that examined outcomes beyond the end of the intervention) suggested no long-term benefit (SMD, -0.01; 95% CI, −0.28 to 0.26), with no strong evidence of heterogeneity in this pooled analysis (I2 = 23.4%, P = .27). There was no strong statistical evidence for small study bias (P > .27). Only 3 studies were assessed as high quality (adequately concealed random allocation, blinded outcome assessment, and intention-to-treat analysis). When we pooled results from these, the estimated beneficial effect of exercise was more modest (SMD, −0.19; 95% CI, −0.70 to 0.31) than the pooled result for all 13 studies, with no strong evidence of benefit.

Conclusions: Our results suggest a short-term effect of exercise on depression: on average, depression scores 0.4 of a standard deviation lower in clinically depressed patients randomly assigned to an exercise intervention at the end of that intervention compared to those randomly assigned to a none exercise group. There is little evidence of a long-term beneficial effect of exercise in patients with clinical depression.

J Clin Psychiatry

Submitted: November 27, 2008; accepted October 5, 2009.

Online ahead of print: October 19, 2010 (doi:10.4088/JCP.08r04913blu).

Corresponding author: Jesper Krogh, MD, Psychiatric Center Bispebjerg, Bispebjerg University Hospital, DK-2400, Denmark ([email protected]).