Exercise can be beneficial for people with depression, according to a new systematic review published in The Cochrane Library. The authors of the review found that exercise can reduce depressive symptoms, although they say more trials are needed to prove this idea. There are about 120 million people worldwide with depression, and antidepressant use and psychological treatment are currently the dominant approaches to fighting depression. However, antidepressants have significant side effects, some patients refuse to use them, and others are unable to receive psychological treatment. Physical exercise has also been used in antidepressant treatment because it can affect the body’s hormone levels and thus change the state of mind, as well as distract patients from dwelling on negative emotions. The Library of Evidence-Based Medicine has published a review of similar studies that found a benefit of exercise in combating depression, but cited less evidence. Now researchers have done more experiments and have more refined results. They did 39 experiments on 2,362 depressed patients, assessing the severity of their symptoms using certain criteria. The researchers found that in 35 trials, exercise had a therapeutic effect on depression in the exercise group compared to the control group (the group that did not have any treatment). Exercise was as effective as taking antidepressants and heart treatments, although these results came from a small number of, small trials. ”Our study shows that exercise has a therapeutic effect on depression,” said one of the authors of the article, Gillian Mead from the Centre for Clinical Brain Science Research at the University of Edinburgh, U.K. “We do not yet have the means to discover which part of the motor area of the brain is most effective in treating depression, and whether the benefits from this exercise will have an effect after the patient stops exercising.” Conducting high-quality evaluations of exercise-related trials is more difficult; for example, it is difficult for researchers not to know which patients are in the experimental group and which patients are in the control group. As a result, researchers have conducted high-quality trials with separate analyses. Among the six trials, the effect of exercise on treating depression was not significant. ”When we focused on the high-quality trials, there was no significant change in the effect of exercise on treating depression,” Mead said, “and we need larger, higher-quality studies to confirm our findings.