Participating in a variety of exercise activities may reduce the
risk of dementia in older people -- and having variety in exercise
seems to be even more important than how often, how long or how
intense the exercise is performed, according to Johns Hopkins researchers.
The study involved 3,375 people aged 65 years and older who took
part in the Cardiovascular Health Cognition Study from 1992 to 2000.
None of the volunteers had dementia at the beginning of the study.
Each participant filled out a questionnaire reporting how often,
and for how long, they performed 15 types of physical activity ranging
from hiking and jogging to household chores and gardening. The researchers
then created an activity index that calculated the number of different
activities each person had participated in over the previous two
weeks (other factors, such as APOE genotype (indicating a predisposition
to Alzheimer's disease), age, gender, smoking and education level
were also taken into account).
After an average of 5.4 years, 480 new cases of dementia were found.
Those who participated in more activities had a lower risk of all
forms of dementia, including Alzheimer's disease and vascular dementia.
However, the association was not found among those who have the
APOE-4 genotype.
Specifically:
- Among the people who reported one or no activity, 130 cases
of dementia occurred.
- 152 cases occurred among those who reported two activities.
- 113 cases occurred among those who reported three activities.
- 84 cases occurred among those who reported four or more activities.
Researchers are not certain what is causing the association, but
suggest that participating in a variety of activities may keep more
areas of the brain active, or may indicate that a person is more
involved in physical and social activities overall.
Confirming the association between activity and a lowered risk
of dementia may motivate people to stay involved in a variety of
physical and leisure activities as they age. This is an important
finding as close to 4.5 million Americans currently suffer from
Alzheimer's disease, the most common form of dementia, and the disease
is expected to affect 11.3 million to 16 million Americans by 2050.
American
Journal of Epidemiology April 1, 2005, 161(7): 639-651
Science
Daily April 14, 2005
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