Exercise for depression

Rimer J, Dwan K, Lawlor DA, Greig CA, McMurdo M, Morley W, Mead GE

Published Online:

July 11, 2012

Depression is a common and disabling illness, affecting approximately 121 million adults worldwide. While depression is commonly treated with antidepressants or psychological therapy, there is increasing interest in the effect of alternative therapies. Exercise has been advocated as a treatment for depression and has been the subject of research for several decades. In our previous Cochrane review, we found that exercise seemed to improve depressive symptoms in people with a diagnosis of depression, but further research was needed. Since then, several new trials have been published. This updated review has identified all available randomised trials which compared exercise with either no treatment or an established treatment (e.g. talking therapy) for people with a diagnosis of depression. We combined data from 30 trials. There were some methodological problems with some of the trials, which limits our confidence in the conclusions drawn. There were 28 trials (1101 participants) that included a comparison of exercise with either waiting list or placebo; overall, we found exercise seemed to improve the symptoms of depression. However, when only the high-quality trials were included, the effect on depression was small. More research is needed to confirm these findings.

Abstract (click to read)

Background:

Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychotherapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression. This is an update of an earlier review first published in 2009.

Objectives:

To determine the effectiveness of exercise in the treatment of depression. Our secondary outcomes included drop-outs from exercise and control groups, costs, quality of life and adverse events.

Search strategy:

We searched the Cochrane Depression, Anxiety and Neurosis (CCDAN) Review Group's Specialised Register (CCDANCTR), CENTRAL, MEDLINE, EMBASE, Sports Discus and PsycINFO for eligible studies (to February 2010). We also searched www.controlled-trials.com in November 2010. The CCDAN Group searched its Specialised Register in June 2011 and potentially eligible trials were listed as 'awaiting assessment'.

Selection criteria:

Randomised controlled trials in which exercise was compared to standard treatment, no treatment or a placebo treatment in adults (aged 18 and over) with depression, as defined by trial authors. We excluded trials of postnatal depression.

Data collection and analysis:

For this update, two review authors extracted data on outcomes at the end of the trial. We used these data to calculate effect sizes for each trial using Hedges' g method and a standardised mean difference (SMD) for the overall pooled effect, using a random-effects model. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis. We systematically extracted data on adverse effects and two authors performed the 'Risk of bias' assessments.

Main results:

Thirty-two trials (1858 participants) fulfilled our inclusion criteria, of which 30 provided data for meta-analyses. Randomisation was adequately concealed in 11 studies, 12 used intention-to-treat analyses and nine used blinded outcome assessors. For the 28 trials (1101 participants) comparing exercise with no treatment or a control intervention, at post-treatment analysis the pooled SMD was -0.67 (95% confidence interval (CI) -0.90 to -0.43), indicating a moderate clinical effect.

However, when we included only the four trials (326 participants) with adequate allocation concealment, intention-to-treat analysis and blinded outcome assessment, the pooled SMD was -0.31 (95% CI -0.63 to 0.01) indicating a small effect in favour of exercise. There was no difference in drop-outs between exercise and control groups. Pooled data from the seven trials (373 participants) that provided long-term follow-up data also found a small effect in favour of exercise (SMD -0.39, 95% CI -0.69 to -0.09). Of the six trials comparing exercise with cognitive behavioural therapy (152 participants), the effect of exercise was not significantly different from that of cognitive therapy. There were insufficient data to determine risks, costs and quality of life.

Five potentially eligible studies identified by the search of the CCDAN Specialised Register in 2011 are listed as 'awaiting classification' and will be included in the next update of this review.

Authors' conclusions:

Exercise seems to improve depressive symptoms in people with a diagnosis of depression when compared with no treatment or control intervention, however since analyses of methodologically robust trials show a much smaller effect in favour of exercise, some caution is required in interpreting these results.

This record should be cited as:

Rimer J, Dwan K, Lawlor DA, Greig CA, McMurdo M, Morley W, Mead GE. Exercise for depression. Cochrane Database of Systematic Reviews 2012, Issue 7. Art. No.: CD004366. DOI: 10.1002/14651858.CD004366.pub5

Assessed as up to date:

February 5, 2010

PEARLS - Practical Evidence About Real Life Situations (click to read)

Clinical question:

How effective is exercise in the treatment of depression?

Bottom line:

Exercise seems to improve depressive symptoms in people with a diagnosis of depression. However, when only methodologically robust trials were included, the effect sizes were only moderate and not statistically significant. The effect of exercise was not significantly different from that of cognitive therapy.

Caveat:

The majority of trials had methodological weaknesses. The number of comparison groups ranged from 2 to 6, and there was wide variation in the type and duration of exercise intervention. The review was unable to be sure how effective exercise is as treatment for people with depression, what constitutes the most effective type of exercise (aerobic, resistance or mixed), whether group or individual exercises are better, or the optimum duration of exercise. There were insufficient data to determine risks and costs.

Context:

Depression is a common illness, affecting at least 1 in 5 people during their lifetime. Exercise has been advocated as an adjunct to usual treatment.

Cochrane Systematic Review:

Mead GE et al. Exercise for depression. Cochrane Reviews 2008, Issue 4. Article No. CD004366. DOI: 10.1002/14651858.CD004366.pub3. This review contains 28 trials involving 1599 participants. Twenty five trials provided data for meta-analyses.

Authored by:

Brian R McAvoy

Cochrane Primary Health Care Field

Health topics:

Mental health > Depression > Depressive disorders & major depression

Cochrane Summaries

Independent high-quality evidence for health care decision making

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