Exercise variety - not intensity - appears to reduce some Alzheimer's disease risk

The variety of leisure and physical activity one engages in -- and not its intensity in terms of calories expended - may
reduce dementia risk in older people, according to researchers at Johns Hopkins. An association between variety of activity
and dementia risk, however, did not hold up in those with the so-called APOE-4 genetic predisposition to the disease found in
about one-quarter to one-third of Alzheimer's patients, according to a report appearing in the April 1, 2005, issue of the
American Journal of Epidemiology.


General physical activity is already known to enhance cardiovascular health and help maintain independence and quality of
life in older people, but the results of this study - which establish a statistical association, and not a direct cause and
effect, between variety of exercise and reduced dementia risk -- suggest that participating in a number of different
activities may be as or more important than frequency, duration, and intensity of physical activity with respect to dementia
risk, according to the report.


"We don't yet know why this association exists or what causes it. It could well be that maintaining a variety of activities
keeps more parts of the brain active, or that this variety reflects better engagement in both physical and social activities.
Confirmation of this association in future studies may provide an additional impetus for people to remain or become engaged
in several physical and other leisure activities later in life," says Constantine G. Lyketsos, M.D., professor of psychiatry
and behavioral sciences at Johns Hopkins and senior author on the report.


The study included 3,375 men and women age 65 years or older who participated in the Cardiovascular Health Cognition Study
from 1992 to 2000 and who did not have dementia at the onset of the study. Each study volunteer was asked to fill out a
questionnaire about the frequency and duration of the 15 most common types of physical activity in older adults, including
walking, household chores, mowing, raking, gardening, hiking, jogging, biking, exercise cycling, dancing, aerobics, bowling,
golfing, general exercise and swimming. The researchers then created an activity index, calculated as the number of different
activities each subject participated in over the previous two weeks. Other measurements, including APOE gentotype, age,
gender, education level, ethnicity, smoking, alcohol use, and other physical and mental health-related history, were also
considered in the study.


The researchers found 480 new cases of dementia over an average of 5.4 years of follow-up. Among these, dementia occurred
less frequently in those participating in more activities relative to those who participated in fewer activities (one or no
activity had 130 cases, two activities had 152 cases, three activities had 113 cases, four or more activities had 84 cases).
The association held true for all types of dementia, including Alzheimer's disease and vascular dementia. The association did
not hold true for those who have the APOE-4 genotype.


"These findings, taken together with recent findings from our colleagues at the University of Chicago studying physical
activity and plaque buildup in the brains of mice with Alzheimer's (published this year in the journal Cell) provide a good
picture from basic and clinical science of how activity and exercise work to reduce the risk of dementia," says Lyketsos.



According to the Alzheimer's Association, dementia is a group of diseases that all gradually destroy brain cells and lead to
progressive decline in mental function. An estimated 4.5 million Americans have Alzheimer's disease, the most common form of
dementia. The number of American's with Alzheimer's disease has more than doubled since 1980 and is projected to reach 11.3
to 16 million by the year 2050.


Other authors of the report are Laura Jean Podewils, Eliseo Gualler, Linda Fried and Michelle Carson of Johns Hopkins, and
Lewis H. Kuller and Oscar L. Lopez of the University of Pittsburg. The research was funded by the National Heart, Lung and
Blood Institute and the National Institute on Aging.


On the Web:

hopkinsmedicine/Psychiatry/Clinical/geriatric.html

aje.oupjournals


Contact: Trent Stockton

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410-955-8665

Johns Hopkins Medical Institutions

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