Michael Babyak, James A. Blumenthal, Steve Herman, Parinda Khatri, Murali Doraiswamy, Kathleen Moore, W. Edward Craighead, Teri T. Baldewicz, and K. Ranga Krishnan
Duke University Medical Center, Durham, North Carolina
Published in 'Psychosomatic Medicine', 62, 633-638, 2000
This study examined the effects of using physical exercise as treatment for people suffering from major depression. 156 adults with major depressive disorder (MDD), who were aged 50 years and older, voluntarily took part in the study. They were randomly assigned to a 4-month course of aerobic exercise, anti-depressant medication, or a combination of aerobic exercise and medication. None of the participants were in any form of psychotherapy at the beginning of the study. Nor were they already taking any anti-depressant medication or participating in any form of aerobic exercise. The main object of the study was to assess depression levels 6 months after completion of the treatment, in order to determine any lasting effects of each treatment method. Depression was therefore measured at baseline (before the treatment began), immediately after the 4-month period, and 6 months after the treatment ceased (i.e. 10 months after the onset of the study).
Participants who were assigned to the exercise group were required to attend three supervised exercise sessions per week for 16 consecutive weeks. Those who were assigned to the anti-depressant medication group were prescribed sertraline (Zoloft) and were monitored by a psychiatrist throughout the 16-week period. The participants who were given both exercise treatment and medication participated in the same exercise programme and received the same anti-depressants as those in the other two groups.
The majority of participants in all three treatment groups demonstrated significantly reduced levels of depression immediately after the 4-month treatment period. In most cases, these improvements in depressive symptoms persisted for at least 6 months after the treatment ended. Among the participants who were classified as being in full remission immediately after the 4-month treatment period, those who were in the exercise group were less likely to relapse compared with those who were given anti-depressant medication.
Furthermore, there were no additional advantages as a result of combining medication and exercise. In fact, relapse rates were greater compared to those within the exercise only group. According to the authors, this was an unexpected finding and they could simply speculate about the reasons for this result. One suggestion was that some participants assigned to this group expressed disappointment at being given medication in addition to exercise and many thought that the anti-depressants were interfering with the beneficial effects of the exercise programme. The authors believe that a sense of personal mastery and positive self-regard plays an important role in the depression-reducing effects of physical exercise and suggest that taking medication may somehow undermine the psychological effects of exercise alone. The authors emphasise the need for future research to consider the attitudes and beliefs that people associate with exercise therapy.
The results also indicated that those who continued to exercise during the 6-month follow-up period reported reduced depressive symptoms therefore the incidence of depression decreased significantly after 10 months. The authors acknowledge that the nature of the study design prevents them from concluding that exercise causes reduced depression and that people who continued to exercise may have done so because they were already less depressed as a result of the treatment. However, the results indicated that the number of minutes of exercise per week still predicted levels of depression 6 months after treatment. People may exercise more because they feel less depressed and in doing so, the continued exercise makes it less likely that the depression will resurface.
In conclusion, the authors suggest that a modest exercise programme is an effective method of treatment for patients with major depression, although some people may be more inclined to embrace it as a 'prescription' for depression than others. Nevertheless, if people are willing to participate in a physical exercise treatment programme for depressive symptoms they are likely to experience significant improvement in their condition and these benefits are likely to endure among those who adopt exercise as a regular, ongoing life activity.
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