Can Exercise Treat Depression?

ABSTRACT & COMMENTARY

Source: Babyak M, et al. Exercise treatment for major depression: Maintenance of therapeutic benefit at 10 months. Psychosom Med 2000;62:633-638.

Exercise is considered a standard part of a multi-faceted treatment program for patients with depression. Studies have indicated that there is an inverse relationship between physical activity and depressive symptoms, and that aerobic exercise may help reduce depression. These studies are limited though, since patients were also receiving concomitant psychotherapy and/or medication. A recent study by Babyak and colleagues revealed that exercise, pharmacotherapy (sertraline 50-200 mg/d), and a combination all resulted in significant reductions in depression at 4-month follow-up; more than 60% of each group improved significantly with no differences between the groups.¹ The exercise intervention involved attending three groups/week for 45 minutes, led by an instructor, in a group format, with individualized evaluations to target 70-85% of heart rate reserve.

The current study evaluated the same cohort over sixadditional months. Participants responded to an advertisement regarding exercise (only) treatment of depression. The diagnosis of depression was confirmed by structured clinical interview. Subjects were excluded if they had a current alcohol or substance problem, medical contraindications to exercise, another primary psychiatric disorder, imminent suicidal thoughts, current psychotherapy, or currently participated in regular aerobic exercise. All subjects were older than 50 years old. Participants were evaluated after six months of treatment, using the Hamilton Depression Rating Scale (HDRS, clinician interview) and the Beck Depression Inventory (BDI, self-report, 21 items). The follow-up care was flexible. In the exercise group, 64% continued exercising (by self report) vs. 66% in the combination care group. Only 26% of the medication group continued medication compared to 40% in the combination group and 7% of the exercise group who subsequently initiated medication. There was no difference between the groups in terms of those who subsequently added concomitant psychotherapy.

Of the 156 completing the original study and entering the current study, 133 completed the follow-up evaluation; there were no differences in the lost-to-follow-up rate between groups. Using the BDI, there was no difference between the groups. Using the HDRS and DSM-IV criteria, the exercise-only group had less recurrence (30%) than the medication (52%) and combination (55%) groups. Multiple logistic regression analysis revealed that those who continued to engage in exercise were less likely to be depressed. Age, gender, baseline depression scores, and antidepressant use did not significantly predict the same.

COMMENT BY DONALD M. HILTY, MD

This study provides some positive, yet to be replicated data, which suggest that depression may be reduced by exercise. However, it is very likely that the sample is not generalizable due to recruitment by advertisement for exercise (i.e., the patients wanted exercise to work and according to Babyak et al, some patients complained about having to take medication). This would explain why the exercise group did better than the combination group, which would otherwise be unlikely. In addition, it may be possible that those who exercised were already less depressed. It is likely, as Babyak et al point out, that there is a reciprocal relationship between depression and exercise—feeling less depressed may make it more likely that patients will continue to exercise, and continuing to exercise may make it less likely that the patient will suffer a return of depression. It is premature to use exercise as a sole treatment in the 4- to 9-month remission period of depression. However, exercise may be a reasonable strategy to incorporate into the treatment of depression, especially for older adults. As previously covered in Psychiatric Medicine in Primary Care (April 2000), both exercise and antidepressants increase the expression of the brain derived neurotrophic factor in the hippocampus of rats.

Reference

1. Blumenthal JA, et al. Effects of exercise on older adults with major depression. Arch Intern Med 1999;159:2349-2356.