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Evidence that exercise helps in depression is still weak, finds review

BMJ 2013; 347 doi: https://doi.org/10.1136/bmj.f5585 (Published 13 September 2013) Cite this as: BMJ 2013;347:f5585
  1. Zosia Kmietowicz
  1. 1BMJ

An analysis of trials that looked at the effectiveness of exercise in treating depression found it to be of moderate benefit, but when the analysis was narrowed to only good quality trials it found no additional benefit in exercise.

The review, from the Cochrane Library, concluded that more large trials are needed to find out whether exercise is as effective as antidepressants or psychological treatments and to pinpoint how much and what type of exercise helps people with depression.1

The last Cochrane review on exercise for depression, published in 2012, found only limited evidence that exercise was helpful, but the publication of several new studies meant an update was needed.

The latest review analysed the results of 39 trials involving 2326 people with a diagnosis of depression. The researchers used Hedges’s g method to calculate effect sizes for each trial and a random effects model risk ratio for dichotomous data to calculate a standardised mean difference (SMD) for the overall pooled effect.

The researchers’ review of 35 trials that compared exercise with control treatment or no treatment in 1356 people found moderate benefit in using exercise to treat depression (SMD −0.62 (95% confidence interval −0.81 to −0.42). And pooled data from eight trials involving 377 people found that exercise had a small effect on mood in the long term (SMD −0.33 (−0.63 to −0.03)).

However, a separate analysis focusing on just high quality trials (six trials, 464 participants) in which the treatment allocated to the participants was adequately concealed found that the effect of exercise was not significant (SMD −0.18 (−0.47 to 0.11)).

Exercise was found to be as effective as psychological therapy (seven trials, 189 people) and antidepressants (four trials, 300 people), although these few trials were small and of low quality. One very small trial (18 participants) found that exercise was more effective than bright light therapy (mean difference −6.4 (−10.20 to −2.6)).

Gillian Mead, from the Centre for Clinical Brain Sciences at the University of Edinburgh and one of the review authors, said, “Our review suggested that exercise might have a moderate effect on depression. We can’t tell from currently available evidence which kinds of exercise regimes are most effective or whether the benefits continue after a patient stops their exercise programme.

“When we looked only at those trials that we considered to be high quality, the effect of exercise on depression was small and not statistically significant. The evidence base would be strengthened by further large scale, high quality studies.”

Notes

Cite this as: BMJ 2013;347:f5585

References

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