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New Study Adds to Evidence that Exercise May Slow
Alzheimer’s and Dementia
 April 26, 2005 - The
new research demonstrates
that long-term physical activity enhances the learning ability of mice
and decreases the level of plaque-forming beta-amyloid protein
fragments - a hallmark characteristic of Alzheimer's disease (AD) - in
their brains. This is the latest of several studies in recent years
claiming exercise can slow Alzheimer’s and dementia. (For other studies
see box on left.)
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Other Studies |
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Two Recent Studies
Exercise Proves Valuable in Lowering Risk for
Alzheimer’s and Parkinson’s
March 15, 2005 – Two of the diseases most feared by
senior citizens – Alzheimer’s and Parkinson’s – may be prevented or
slowed by exercise, according to two recent studies. The Alzheimer’s
study showed that middle-aged people taking regular exercise at least
twice a week could reduce their risk of developing Alzheimer's disease
by 50 percent. The Parkinson’s study found that men who exercised
regularly and vigorously early in their adult life lowered risk for
Parkinson's by as much as 60 percent.
Read more...
Alzheimer’s Risk Lowered by Exercise Variety – Not
Intensity
April 14, 2005 - 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.
Read
more...
Older Men Show Less Cognitive Decline by Maintaining
Physical Activity
Dec. 28, 2004 - Longer and more intense physical
activity may help people maintain their cognitive skills as they age,
according to a 10-year study of elderly men published in the December
28, 2004 issue of Neurology, the scientific journal of the American
Academy of Neurology.
Read More...
12/28/04*
Two
Studies of Older Adults Confirm Exercise Reduces Dementia Risk
Sept. 21, 2004 – Two studies – one of older men and
the other of older women – confirm that exercise, even walking, can mean
a reduced risk of dementia.
Read
More... 9/21/04*
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A number of population-based studies suggest that
lifestyle interventions may help to slow the onset and progression of
AD. Because of these studies, scientists are seeking to find out if and
how physically or cognitively stimulating activity might delay the onset
and progression of Alzheimer's disease.
In this study, scientists have now shown in an
animal model system that one simple behavioral
intervention--exercise--could delay, or even prevent, development of
AD-like pathology by decreasing beta-amyloid levels.
Results of this study, conducted by Paul A. Adlard,
Ph.D., Carl W. Cotman, Ph.D., and colleagues at the University of
California, Irvine, are published in the April 27, 2005, issue of The
Journal of Neuroscience. The research was funded in part by the National
Institute on Aging (NIA), a component of the National Institutes of
Health, U.S. Department of Health and Human Services. Additional funding
was provided by the Christopher Reeve Paralysis Foundation.
To directly test the possibility that exercise (in
the form of voluntary running) may reduce the cognitive decline and
brain pathology that characterizes AD, the study utilized a transgenic
mouse model of AD rather than normal mice. The transgenic mice begin to
develop AD-like amyloid plaques at around 3 months of age.
Initially, young mice (6 weeks or 1 month of age)
were placed in cages with or without running wheels for periods of
either 1 month or 5 months, respectively. Mice with access to running
wheels had the opportunity to exercise any time, while those without the
wheels were classified as "sedentary."
On 6 consecutive days after the exercise phase, the
researchers placed each mouse in a Morris water maze to examine how fast
it could learn the location of a hidden platform and how long it
retained this information. (This water maze task involves a small pool
of water with a submerged platform that the mouse must learn how to
find.)
The animals that exercised learned the task faster.
Thus, the mice that used the running wheels for 5 months took less time
than the sedentary animals to find the escape platform. The exercised
mice acquired maximal performance after only 2 days on the task, while
it took more than 4 days for the sedentary mice to reach that same level
of performance. This suggests that exercise may help to offset
learning/cognitive deficits present in AD patients.
Next, the investigators examined tissues from the
brains of mice that had exercised for 5 months. They compared the levels
of plaques, beta-amyloid fragments, and amyloid precursor protein, a
protein found throughout the body and from which the beta-amyloid
peptide is derived. In AD, beta-amyloid fragments clump together to form
plaques in the hippocampus and cerebral cortex, the brain regions used
in memory, thinking, and decision making.
Compared to the sedentary animals, mice that had
exercised for 5 months on the running wheels had significantly fewer
plaques and fewer beta-amyloid fragments (peptides) in the cerebral
cortex and hippocampus, approximately by 50 percent. Additional studies,
of exercised animals at 10 weeks old, showed that the mechanism
underlying this difference began within the first month of exercise.
"These results suggest that exercise--a simple
behavioral strategy--in these mice may bring about a change in the way
that amyloid precursor protein is metabolized," says D. Stephen Snyder,
Ph.D., director of the etiology of Alzheimer's program in the NIA's
Neuroscience and Neuropsychology of Aging Program. "From other research,
it is known that in the aging human brain, deposits of beta-amyloid
normally increase. This study tells us that development of those
deposits can be reduced and possibly eliminated through exercise, at
least in this mouse model."
These findings follow another recent report of a
link between an enriched environment and Alzheimer's-like brain changes.
That study, published Orly Lazarov, Ph.D., and colleagues in the March
11, 2005, issue of the journal Cell, found that beta-amyloid levels
decreased in the brains of another kind of transgenic mice when they
were housed in groups and in environments that were enriched with
running wheels, colored tunnels, and toys.
"Both of these studies are exciting because they
offer insight into one of the pathways through which exercise and
environment might promote resistance to development of cognitive changes
that come with aging and AD," Snyder notes. "It is as though exercise or
environmental enrichment forces the metabolism of amyloid precursor
protein through a pathway that is less harmful and might even be
beneficial. Further research will help us to understand those
mechanisms, to learn how much and what kind of exercise is best, and to
see if these same effects occur in humans."
For more information on participation in an AD
clinical trial, visit
http://www.clinicaltrials.gov/ (search for Alzheimer's disease
trials), or the Alzheimer's Disease Education and Referral (ADEAR)
Center website at
http://www.alzheimers.org. ADEAR may also be contacted toll free at
1-800-438-4380. The ADEAR Center is sponsored by the NIA to provide
information to the public and health professionals about AD and
age-related cognitive change and may be contacted at the website and
phone number above for a variety of publications and fact sheets, as
well as information on clinical trials.
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