Researchers say they have found evidence to support previous research that suggests exercise may reduce symptoms of depression, according to a review published in The Cochrane Library.
The updated systemic review, conducted by UK researchers, analyzed the Cochrane Depression, Anxiety and Neurosis Review Group's Controlled Trials Register (CCDANCTR), which includes randomized controlled trials from various bibliographic databases.
The previous version of the review found only limited evidence to suggest that exercise could benefit people suffering from depression. However, the researchers have now carried out further investigation after more trials have since been conducted.
The researchers analyzed 35 trials involving a total of 1,356 participants who were clinically diagnosed with depression. Patients who underwent exercise in line with recommendations from the American College of Sports Medicine were monitored.
These patients were compared with those who received the following treatment for their symptoms of depression:
- Standard treatment
- No treatment or placebo treatment
- Pharmacological treatment
- Psychological treatment
- Other active treatment.
Exercise shows 'moderate benefits' for depressive symptoms
When comparing patients who carried out exercise with those who underwent no treatment or control treatments, those who exercised showed moderate benefits regarding depressive symptoms.
The researchers found that exercising proved as effective as psychological therapy or taking antidepressants. They add, however, that these findings were based on only a small number of low-quality trials.
The study authors say:
"Exercise is moderately more effective than a control intervention for reducing symptoms of depression, but analysis of methodologically robust trials only shows a smaller effect in favor of exercise.
When compared to psychological or pharmacological therapies, exercise appears to be no more effective, though this conclusion is based on a few small trials."
When conducting a closer analysis on six trials that were of higher quality, however, the researchers found that the effects of exercise on depression was weaker.
Higher quality studies needed
"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," says Gillian Mead of the Centre for Clinical Brain Sciences at the University of Edinburgh in the UK and study author.
Overall, the researches say they are unable to say at present what level of exercise may reduce symptoms of depression, and that further studies will be needed to determine this.
"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 program," she adds.
Previous research from the Harvard School of Public Health suggests that low levels of exercise and watching lots of TV are each linked to higher risk of depression.