Exercise, A Depression Antidote

A modest amount of regular exercise effectively relieves mild to moderate depression, according to a study published in the American Journal of Preventive Medicine (2005;28:1-8).

Mild to moderate depression is a leading cause of disability and premature death in the developed world, second only to heart disease. Symptoms include depressed mood, loss of interest in activities, body weight loss or gain, insomnia or excessive sleeping, fatigue or loss of energy, and inability to concentrate. Antidepressant medications are often prescribed to treat depression, which usually work by increasing brain levels of serotonin or norepinephrine, chemical messengers (neurotransmitters) that calm or excite the nervous system and improve mood. Although they are generally effective at relieving mild to moderate depression symptoms, some of these medicines can cause serious and uncomfortable side effects, including sexual dysfunction. Other treatment approaches include psychotherapy, dietary changes such as sugar and caffeine restriction, herbal remedies such as Saint John’s wort, and exercise. A number of studies have found that exercise can reduce the symptoms of depression, and one study found that it can be as effective as medication in treating mild to moderate depression.

The current study tested the effects of exercise on 80 people between the ages of 20 and 45 who had untreated mild to moderate depression and had not been exercising regularly at the beginning of the study. They were randomly assigned to one of five groups: a low-dose/low-frequency exercise group, a low-dose/high frequency group, a moderate-dose/low-frequency group, a moderate-dose/high frequency group, and a placebo group. Researchers defined a low dose of exercise as expending 3 calories per pound of body weight each week, and a moderate dose as expending 8 calories per pound per week, an amount that meets current public health recommendations. The low-frequency groups exercised three times per week, and the high-frequency groups exercised five times per week. People in the exercise groups exercised with supervision, using a treadmill or stationary bicycle at each session, and the placebo group did only stretching. A well-established rating scale for measuring the symptoms of depression was used weekly to assess progress. At the end of 12 weeks, depression scale scores in people in the moderate-dose exercise groups improved significantly more than those in the low-dose groups and those in the placebo group; there was no significant difference in improvement between the low-dose and placebo groups. Exercise frequency did not affect depression scale scores.

The results of this study add to the evidence that exercise can relieve the symptoms of mild to moderate depression in people using no other treatment. Furthermore, these findings show that the amount of exercise currently recommended by public health officials is effective, but an amount of exercise that expends less energy is not. Based on these findings, healthcare providers can offer current exercise guidelines to people with mild to moderate depression: at least 30 minutes of moderate-intensity exercise on most days of every week.

Maureen Williams, ND, received her bachelor’s degree from the University of Pennsylvania and her Doctorate of Naturopathic Medicine from Bastyr University in Seattle, WA. She has a private practice in Quechee, VT, and does extensive work with traditional herbal medicine in Guatemala and Honduras. Dr. Williams is a regular contributor to Healthnotes Newswire.

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