Regular excercise may fight depression as effectively as prescription medication does, researchers say. According to a report published in the September/October issue of the journal Psychosomatic Medicine, patients who followed a modest excercise regimen fared as well as patients who took the antidepressant known as Zoloft.

Some 150 volunteers, all of whom were at least 50 years old and diagnosed with depression, followed one of three treatment programs: exercise, Zoloft or a combination of both. Participants in the exercise group worked out on a treadmill or stationary bicycle at 70 to 85 percent of their maximum heart rate for 30 minutes three times a week. Those receiving combination treatment followed the same exercise routine. At the end of the four-month study period, all three groups displayed significantly lower depression rates. Moreover, follow-up examinations six months later revealed that subjects in the excercise group experienced significantly lower relapse rates than those given the Zoloft or combination treatments.

Exactly why people in the combination group did not experience the same long-term benefits as those in the exercise-only group is unclear. But lead author James A. Blumenthal of Duke University speculates that "it is conceivable that the concurrent use of medication may undermine the psychological benefits of exercise by prioritizing an alternative, less self-confirming attribution for one's improved condition." That is, rather than feeling that their hard work had paid off, patients in the combination group may have attributed their improved mental state to the medication alone.

As impressive as these results are, the researchers caution that exercise may not bring relief to every person suffering from depression since, Blumenthal says, "exercise prescribed by a clinician may not be accepted and complied with to the same extent as when it is sought out and adopted on one's own," as in the case of the study participants. "The question remains whether the impressive results of this study will be applicable to the general population of middle-aged and older patients with major depressive disorders."