Evidence suggests that physical activity may be related to the clinical expression of dementia, according to background information in the article. Whether the association includes low-intensity activity such as walking has not been known.
Robert D. Abbott, Ph.D., of the University of Virginia School of Medicine, Charlottesville, Va., and colleagues examined the association between walking and future risk of dementia in older men.
The study included 2,257 physically capable men aged 71 to 93 years in the Honolulu-Asia Aging Study. Distance walked per day was assessed from 1991 to 1993. Follow-up for incident dementia was based on neurological assessment at 2 repeat examinations (1994-1996 and 1997-1999).
The researchers found that after adjusting for age, men who walked the least (less than 0.25 mile/day) experienced a 1.8-fold excess risk of dementia compared with those who walked more than 2 miles/day. Men who walked 0.25 to 1 mile/day experienced a 71 percent increased risk of dementia compared to men who walked the most (more than 2 miles/day). These associations persisted after accounting for other factors, including the possibility that limited amounts of walking could be the result of a decline in physical function due to preclinical dementia.
"There are no clear explanations for the relation between walking and dementia," the authors write. "Although associations were independent of other study characteristics that were determined at the time when walking was assessed, it may be that men who walk frequently are more resistant to risk factor changes or transitions into adverse risk factor states. Although changes in risk factor status in the course of follow-up were not considered in the current study (nor were such data always available), it would be important to determine if men who walk regularly are less prone to development of intervening conditions that have a closer link with dementia."
"Although complex, this study and past evidence suggest that walking and active lifestyles in general are associated with a reduced risk of dementia," the researchers conclude.
(JAMA. 2004; 292: 1447-1453. Available post-embargo at www.jama.com.)
Editor's Note: This study was supported by grants from the National Institute on Aging, the National Heart, Lung, and Blood Institute, the National Institute of Neurological Disorders and Stroke, and by the Office of Research and Development, Medical Research Service, Department of Veterans Affairs.
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JAMA