To Treat Depression, a Healthy Dose of Exercise

When recommending treatment for clinical depression, physicians typically prescribe a tried-and-true regimen: anti-depressant medication and "talk" therapy. In the future, however, health professionals may be advocating a healthy dose of exercise.

"It may have a potentially important role in treatment," explains James Blumenthal, Ph.D., professor of medical psychology in the department of psychiatry and behavioral sciences at Duke University, and a lead researcher in the National Institute of Health's "Exercise Training and Depression in Older Adults" study.

The study analyzed exercise as an alternative treatment for depression among older adults. "Results from our study suggest that exercise was as effective as medication in reducing depression in patients with moderate-severe as well as mild depression," he says. And for patients who worry about the stigma associated with depression and other forms of mental illness, working out may seem more palatable than a prescription or the prospect of psychotherapy.

It works, but we don't know why

While many experts acknowledge exercise can prove beneficial in treating less severe forms of depression, they have yet to reach consensus on the most basic question: Why?

Some experts theorize that intense workouts can stimulate production of serotonin, a brain chemical that's been linked to mood. Others contend that exercise increases the level of endorphins. As the body's natural painkillers, endorphins can sometimes create a feeling of euphoria. And then there are experts who argue that the true benefit of exercise isn't physiological at all -- it's psychological. In other words, you feel better after you exercise because you're relieving stress and leading a more healthy life. This, in turn, helps improve confidence and self-esteem.

"I believe each of these theories are plausible," Dr. Blumenthal says. "But the truth is, we don't know the mechanisms or what chemicals are released."

Even more confounding, there's no evidence to suggest one form of exercise is more effective than another in treating depression. Most studies have measured the effects of aerobic activity, such as running, but others indicate non-aerobic exercise like weight training can have an equally positive impact. Researchers have also been unable to determine how long, how intense or how often patients must exercise to experience a marked decrease in depressive symptoms. Studies have shown, however, that improvements are greatest after four months of regular exercise.

Understandably, physicians have been slow to replace traditional therapies with exercise. Research is in the pioneering stage, and scientists still have many questions to answer before exercise ever becomes a prescribed -- much less preferred -- method for treating depression. Plus, testing the efficacy of exercise versus other treatments inherently puts the patient at risk because it takes him or her off a proven course of treatment -- an especially dangerous proposition when dealing with severely depressed individuals.

"The jury's still out," Dr. Blumenthal says. "It's a big step from exercising in a group [such as in a study] to getting a prescription to exercise on your own."

There's no harm in trying

Given the uncertainty, it begs the question: Should patients with depression bother to exercise?

"For people who are physically able, adding exercise as an adjunct to other treatment certainly wouldn't hurt," says Andrea Dunn, Ph.D., associate director of the Dose Response Study, a research project partially funded by the National Institutes of Mental Health and the Cooper Institute for Aerobic Exercise and Depression Research in Dallas, Texas. "Some physicians who prescribe cognitive behavioral therapy [psychotherapy] and medication therapy ask their patients to exercise because they believe it helps improve the effectiveness of those treatments. And, there's some anecdotal clinical evidence to suggest exercise does help make those treatments more effective."

Until more is known about the link between exercise and depression, Dr. Dunn and other experts recommend physical training be used to complement traditional forms of treatment. If nothing else, exercise helps people escape the cycle of inactivity that often accompanies depression, and exercise has other known health benefits.

The key, however, is to be realistic; researchers stress that getting in shape or losing weight may be a healthy side effect, but it isn't an essential outcome for an exercise regimen. In fact, studies show that walking or running 20 minutes to an hour, three to five times per week, is reasonable -- and effective.