uk Mailing List: Fitness and the Brain: Can a Walk a Day Keep Alzheimer's Away?

[Dwiriana Setiati (dwiriana.setiati]

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November 25, 2008 in Mind & Brain <http://www.sciam.com/mind-and-brain> | 1
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Fitness and the Brain: Can a Walk a Day Keep Alzheimer's Away? A new study
looks at the connection between exercise and memory loss

By P. Murali Doraiswamy and Benson Hoffmann



**
Michael Krinke/iStockphoto

In the U.S. some five million people have Alzheimer's disease and 10 million
boomers will be at risk for memory problems over their lifetime. Worldwide,
more than 100 million people may have Alzheimer's by the year 2050. As
clinicians, we have learned to recognize that jokes about "old-timer's
disease" and "Teflon brain" are often calls for help from seniors worried
about their memory
lapses<http://www.sciam.com/article.cfm?id=partial-recall-why-memory-fades>.
Living longer is obviously no fun if you cannot
remember<http://www.sciam.com/article.cfm?id=delaying-dementia>your
home address or drive a car. Although we have made tremendous progress
in understanding brain changes that accompany aging and dementia, no
medications have proven effective for preventing Alzheimer's to date. In
recent years, however, more evidence is pointing to a non-medical way to
bolster brain health as we age: exercise.

*The Benefits of Exercise*
Scientists are excited about the prospects of physical activity and exercise
as anti-Alzheimer strategies for many reasons.
Exercise<http://www.sciam.com/article.cfm?id=exercise-may-improve-func>training
has been shown to reduce risk factors for dementia such as blood
pressure, cholesterol <http://www.sciam.com/topic.cfm?id=cholesterol>,
diabetes and depression <http://www.sciam.com/topic.cfm?id=depression>.
Studies in animal models of aging show that exercise can increase blood
flow, stimulate nerve cell growth in regions associated with memory and
reduce the pathologic changes characteristic of Alzheimer's. Studies of
exercise and memory in humans have been promising but not yet definitive.
For example, some, but not all, observational studies of older adults time
found that those who were more physically active (for example, in such
activities as swimming, walking, ballroom dancing) or who exercised at least
three times a week had a lower risk for dementia. Likewise some short-term
clinical trials found that aerobic exercise improved certain cognitive
abilities. The inconsistency across studies has hampered firm conclusions
about the relevance of these findings, however. What was needed to move the
field forward was a clinical trial testing whether regular exercise could
produce sustained long-term improvements in older adults with memory
problems.

In a 
study<http://www.ncbi.nlm.nih.gov/pubmed/18768414?ordinalpos=18&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_DefaultReportPanel.Pubmed_RVDocSum>published
in September 2008, Nicola Lautenschlager and colleagues at the
University of Western Australia attempted to do just that. They studied 170
older people with memory complaints of whom 60 percent had objective memory
deficits severe enough to be diagnosed with mild cognitive impairment, a
condition thought to be a precursor for Alzheimer's.

Over the next six months, half of the study participants were assigned to a
home-based exercise program. They were encouraged to do at least three
50-minute sessions of exercise (mostly walking) each week. Those who were
already doing this level of exercise at study entry (about 25 percent) were
asked to up their activity level by an additional 50 minutes. The other half
were assigned to receive basic health education as a control group. At the
end of six months, exercisers improved modestly (scoring about 20 percent
higher than controls) on an overall measure of cognitive abilities. The
subgroup of people with mild cognitive impairment also improved. One year
after the trial ended, the exercisers still sustained a 10 percent edge on
overall cognitive score compared with controls and also had significantly
less decline on a memory measure. A host of other cognitive subtests did not
differ between the groups, however. This study is important because it is
the first to demonstrate that exercise benefits cognition in older adults
with subjective and objective memory problems over 18 months.

*Further Questions*
But this study was not a clean win and raises additional questions. The
effect size was too small for an average person to be able to notice a
benefit (although any effect is better than nothing in a field with no
alternatives). Compliance with exercise decreases over time: Can we motivate
people to sustain exercise habits over long periods? Are memory benefits
seen only with aerobic exercise or can any type of physical activity help?
This study did not follow people long enough to address the billion dollar
question: Can regular exercise postpone the development of Alzheimer's
disease? The study by Lautenschlager and colleagues provides an important
proof of principle and will help us design future trials to test these
issues further. The availability of newer brain scans will also help us
directly track whether exercise can affect the progression of Alzheimer
brain pathology in people at risk. It has been said that "a man's health can
be measured by which he takes two at a time—pills or stairs." As our society
grows increasingly reliant on medications, lifestyle strategies such as
exercise seem like, well, a no brainer.