Fitness and Parkinson's Disease

Summarized by Robert W. Griffith, MD
April 10, 2006

Introduction

Clinical studies have shown that physical therapy can improve the abilities and quality of life for patients with Parkinson's disease. So it would be helpful to know if physical fitness might prevent or delay the onset of the disease in otherwise healthy individuals. This problem was investigated by Harvard researchers; they've published their results in the journal Neurology, and we provide a brief summary here.

What was done

Two collections of volunteers were used - the Health Professionals Follow-Up Study (HPFS) and the Nurses Health Study (NHS); the former were male, the latter female. The HPFS started enrollment in 1986, entering 51,500 men aged 40 to 75. The NHS started in 1976 when 121,000 registered nurses aged 30 to 55 were enrolled.

Information was obtained by questionnaires administered at baseline and then every 2 years. The topics covered were general health, major medical events, and physical activity. Exercise was assessed using the number of hours a week participants spent on energetic activities like hiking, jogging, running, bicycling, swimming, tennis, and so on. Total physical activity was expressed in metabolic equivalent tasks (METS), where the energy for each activity was multiplied by the time spent on it. Participants were also asked about their levels of strenuous activity as young adults.

A specific question on Parkinson's disease was included in the questionnaires from 1988 (HPFS) and 1994 (NHS) onwards. After permission had been granted, the subject's neurologist was contacted to confirm the diagnosis. In some cases, medical records were consulted.

For the analyses, participants were classified into 5 groups, called quintiles, according to their amount of physical activity.

What was found

The average ages across the two populations were 54½ (men) and 52½ (women). The more active participants were less likely to be smokers; they drank less coffee but more alcohol, and were leaner.

There were 252 men and 135 women who developed Parkinson's disease during the course of the study. They were, on average, 70 and 65, respectively, when Parkinson's symptoms first appeared.

Compared with the least active men (those in the lowest quintile), the most active men (the highest quintile) had a 30% lower risk of developing Parkinson's disease. Those who had exercised strenuously as young adults had a 60% lower risk of Parkinson's.

In women, there was no obvious relationship between amount of physical activity during the study period and the development of Parkinson's. However, those who had exercised strenuously as young adults had a 50% decreased risk of developing the disease.

Significant declines in physical activity were seen in both men and women with Parkinson's disease - already present 12 years before the diagnosis in men, and 2 to 4 years before the diagnosis in women.

What these results mean

There seem to be two possible explanations for these findings: either higher levels of physical activity lower the risk for men of contracting Parkinson's disease, or men that are predisposed to the disease tend to avoid strenuous activity in their early adult years. However, the activity changes reported prior to diagnosis may merely reflect increased fatigue - one of the earliest presenting symptoms of Parkinson's.

Why were the findings in women less pronounced, or less clear-cut? This may have been because there were relatively few cases of Parkinson's reported in the women (about half those seen in men) and so were more easily affected by random variations; and the women exercised less, in general, than the men. However, a gender difference in susceptibility to Parkinson's cannot be excluded . . .

Source

• Physical activity and the risk of Parkinson disease. H. Chen, SM. Zhang, MA. Schwarzschild,  et al., Neurology, 2005, vol. 64, pp. 664--669

Related Links
Parkinsonpoly: Role of Exercise
National Parkinson Foundation
PDF: Exercise May Slow Parkinson's

Please take a moment to give us your comments. For questions about Health matters you may check our "Questions & Answers" Portal and Service.