Published: Oct. 24, 1999
Updated: Sept. 29, 2005
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By Duke Medicine News and Communications
DURHAM, N.C. -- A brisk 30-minute walk or jog around the track three times a week may be just as effective in relieving the symptoms of major depression as the standard treatment of anti-depressant medications, according to the results of a Duke University Medical Center study.
The researchers studied 156 elderly patients diagnosed with major depressive disorder (MDD) and assigned them to three groups: exercise, medication, or a combination of medication and exercise. To the surprise of the researchers, after 16 weeks all three groups showed statistically significant and similar improvement in measurements of depression.
"One of the conclusions we can draw from this is that exercise may be just as effective as medication and may be a better alternative for certain patients," said the lead researcher, Duke psychologist James Blumenthal, who published the results of his team's study in the Oct. 25 issue of The Archives of Internal Medicine. The research is supported by a number of grants from the National Institutes of Health.
"While we don't know why exercise confers such a benefit, this study shows that exercise should be considered as a credible form of treatment for these patients," Blumenthal said in an interview. "Almost one-third of depressed patients in general do not respond to medications, and for others, the medications can cause unwanted side effects. Exercise should be considered a viable option."
While the researchers studied middle-aged and elderly people, Blumenthal said the results probably hold true for the general population. "Because the elderly tend to have additional medical problems that might make regular exercise difficult, this is the most difficult group to test the exercise hypothesis."
Symptoms of MDD, as defined by the psychiatric reference book Diagnostic and Statistical Manual IV (DSM-IV), include depressed mood or loss of interest or pleasure combined with at least four of the following: sleep disturbances, weight loss, changes in appetite, psychomotor agitation, feelings of worthlessness or excessive guilt, impaired cognition or concentration and recurrent thoughts of death.
Based on the DSM-IV definition of depression, 60.4 percent of the patients who only exercised were no longer depressed after 16 weeks, compared with 65.5 percent for the medication group and 68.8 percent of the combination group. When a second commonly used measure of depression, the Hamilton Rating Scale for Depression, was added, 47.2 percent of exercise group were no longer considered depressed, compared to 56 percent of medication group and 47 percent of combination.
In both cases, according to Blumenthal, the differences between the groups were not statistically significant.
Researchers did note that patients who took the anti-depressants saw their symptoms relieved sooner, but by 16 weeks the group differences had disappeared.
Blumenthal said it was possible that the structured and supportive atmosphere of the exercise program also could have an effect in improving the symptoms of the exercise group, but he doesn't attribute the majority of the benefit to social support. Studies have shown that improved levels of physical fitness are related to improved symptoms of depression, he said. Nevertheless, early next year, Blumenthal plans to begin a new study to gauge the effect of exercising in a less-supportive atmosphere, and he also plans to include a placebo group.
Blumenthal suggested that exercise may be beneficial because patients are actually taking an active role in trying to get better.
"Simply taking a pill is very passive," he said. "Patients who exercised may have felt a greater sense of mastery over their condition and gained a greater sense of accomplishment. They felt more self-confident and had better self-esteem because they were able to do it themselves, and attributed their improvement to their ability to exercise.
"These findings could change the way some depressed patients are treated, especially those who are not interested in taking anti-depressants," Blumenthal said. "While these medications have been proven to be effective, many people want to avoid the side effects or are looking for a more 'natural' way of feeling better."
The anti-depressant used in the study was sertraline (trade name Zoloft), which is a member of a class of commonly used anti-depressants known as selective serotonin reuptake inhibitors.
Blumenthal cautions that the study did not include patients who were acutely suicidal or had what is termed psychotic depression. Also, because patients were recruited by advertisements, these patients were motivated to get better and interested in exercise.