First comprehensive examination of strenuous physical activity and the risk of developing Parkinson's disease

In the first comprehensive examination of strenuous physical activity and the risk of developing Parkinson's disease, researchers from the Harvard School of Public Health (HSPH) have found that men who exercised regularly and vigorously early in their adult life had a lower risk for developing Parkinson's disease compared to men who did not. The findings appear in the February 22, 2005 issue of the journal Neurology.

Parkinson's disease is a progressive nervous disease occurring generally after age 50. It destroys brain cells that produce dopamine and is characterized by muscular tremor, slowing of movement, rigidity and postural instability.

Men who were the most physically active at the start of the study cut their risk of developing Parkinson's disease by 50 percent compared to men study participants who were the least physically active. The authors also found that men who reported regularly having engaged in strenuous physical activity in early adult life cut the risk for Parkinson's by 60 percent compared to those who did not.

Among women in the study, strenuous activity in the early adult years was also linked to a lower risk of Parkinson's, but this relationship was not statistically significant, and there was no clear relationship between physical activity later in life and Parkinson's risk.

To examine the relationship between physical activity and Parkinson's disease, participants were chosen from the Health Professionals Follow-Up Study at HSPH and the Nurses' Health Study, a Brigham and Women's Hospital-based study. More than 48,000 men and 77,000 women, who were free of Parkinson's disease, cancer or stroke, were included. Participants completed comprehensive questionnaires on disease, lifestyle practices and physical and leisure time activities beginning in 1986 and were updated every two years through 2000. During the course of the study, 387 cases of Parkinson's disease (252 men and 135 women) were diagnosed among the study participants.

The questionnaires contained inquiries on activities such as walking, hiking, jogging, running, bicycling, lap swimming, tennis, squash, racquetball, aerobic exercising and other activities. Additionally, participants were asked to report the number of flights of stairs they climbed per day ranging from two to 15.

Alberto Ascherio, senior author and associate professor of nutrition and epidemiology at the Harvard School of Public Health, said: "These are intriguing and promising findings that suggest that physical activity may contribute to the prevention of Parkinson's. A protective effect of physical activity has been recently found in an animal model of Parkinson's disease -- this convergence of epidemiological and experimental data is what we are looking for, because consistent results are more likely to reflect biological mechanisms with important clinical implications. Future studies should also address the possibility that physical activity slows the progression of Parkinson's."

The research was funded by the National Institutes of Health, National Institute for Neurological Diseases and Stroke and the Kinetics Foundation.