Is exercising to prevent depression just wishful thinking?

Lisa Cooper-Patrick, M.D. Assistant Professor of Medicine, Johns Hopkins School of Medicine       YES Exercise provided no protective effect against depression in a cohort of white males we followed from the Precursors Study-a longitudinal follow-up of 1,337 former Johns Hopkins medical students from the classes of 1948 through 1964. The risk of depression was similar for those who exercised and those who did not. There was no relationship between the level of physical activity and subsequent psychiatric distress.   The data were from 973 doctors. The first analysis assessed the relationship between self-reported physical activity in 1978 and the rate of clinical depression through 1993. The second assessed the relationship between self-reported activity in 1986 and psychiatric distress by the General Health questionnaire in 1988. Participants were asked how often a week they exercised to sweat.   We were surprised by the results. Our first hypothesis was that physical activity would be protective against depression and psychiatric distress. Our second was that the protective effect would be accentuated in vulnerable individuals, in particular those with an “unstable” temperament or with a parental history of depression.   The results support neither hypothesis. The rate of depression in both groups over 15 years was 6.4%, and the psychiatric-distress rates were 15%. Even our assumption about a protective effect for people with a family history was not supported. Of 90 such physicians, nine developed depression. All exercised.   We know that exercise benefits health. Our study is no excuse not to exercise. But the study may strengthen the case for caution in recommending treatments or behavior changes that are not based on solid evidence. We wanted to believe that exercise could prevent depression. It doesn’t.

John Foreyt, Ph.D. Professor of Medicine, Baylor College of Medicine, Houston       NO Our studies have found that exercise helps prevent depression. The Hopkins findings were surprising to them and us.   A positive effect of exercise in preventing depression is fairly well accepted and has been shown in many studies. The fact that the Hopkins group’s well-done study found no benefit makes one wonder whether it was due to the fact that the group was entirely composed of male physicians. Females report depression much more often than men.   Our research, published in the International Journal of Obesity, was based on a cohort from the Reno Diet Heart Study. It looked at cardiovascular risk from 1985 through 1996 in a healthy population. We examined data on diet and exercise from 381 patients over a five-year period-an equal number of men and women evenly spread out by decades (20s through 60s), and an equal number of people who were obese and nonobese.   We found that people who exercise have less depression than people who don’t. The more exercise, we found, the greater the feeling of well-being. No one in the group studied was clinically depressed. Well-being was the endpoint of the study.   I suspect that exercising prevents depression by making people feel good about themselves. People who feel good about themselves report having a better sense of control over their lives, which is the antithesis of depression.   I hope the Hopkins group reviews its data and redoes its studies with other populations. One should not be discouraged by a single anomalous study. And even if exercise proves to have no effect in preventing depression, all its other benefits are so important that I would encourage people to exercise in any case.