People don't have to run marathons to keep their brain
cells in shape -- regular, light activity may do the trick.
In the first study to show that lifelong exercise decreases
cellular aging in the brain, scientists from the McKnight
Brain Institute of the University of Florida say that
moderately active rats have healthier DNA and more robust
brain cells than their less active counterparts. The research
was at the Society for Neuroscience's 35th annual meeting
in Washington, D.C.
"It would be wonderful if we had a pill that contained
all the benefits of exercise, but we don't," said Thomas
Foster, Ph.D., the Evelyn F. McKnight chair for brain
research in memory loss at the College of Medicine. "For
this study animals were not forced to run; they did it
because it was entertaining, the same as a pet hamster
on a running wheel. The results show that regular mild
exercise can prevent oxidative damage. In people, that
translates to a daily 30-minute walk or a light 1-mile
run."
Oxidative damage in the brain is believed to be a natural
consequence of aging and a contributor to memory loss.
In addition, increased oxidative damage has been implicated
in the loss of brain cells that is associated with Alzheimer's
disease and Parkinson's disease.
Oxidative damage can occur when molecules of oxygen gain
electrons and become free radicals. The free radicals
regain their balance by giving electrons to their neighbors.
Most of the time the body routinely handles these renegades,
but sometimes not before extensive damage occurs in the
cell. Working with Christiaan Leeuwenburgh, Ph.D., an
associate professor of aging and geriatric research at
UF's Institute on Aging, Foster looked at groups of rats
that had lived to old age. Some were more sedentary, while
others had access to an exercise wheel.
At the end of the experiment, scientists examined chemical
compounds in 41 tissue samples taken from a part of the
brain important for balance and movement.
The more active rats were found to have fewer byproducts
of oxidative stress in their brains. Fats known as lipids
that help stabilize cell membranes, and DNA, the molecule
that contains our genetic blueprint, both better withstood
the rigors of time.
"The DNA for these animals after two years looked as
if it were from their younger counterparts of only about
6 months of age," Foster said. "It shows a little bit
of exercise may stimulate the body to fight stress that's
normally occurring in the brain."
Damage to DNA causes cell mutations and cell death. Finding
ways to preserve it may help prevent age-related memory
loss and defend against deterioration of balance and motor
function -- important health goals as the U.S. population
continues to age. The 2000 Census shows 34.9 million Americans
are 65 or older. That amount is projected to grow to 47
million by 2020.
"There have been implications that exercise is beneficial
for preventing neurological diseases and aging impairments,
but these studies put a molecular imprint on what might
be happening," said Eric Klann, Ph.D., a professor of
molecular physiology and biophysics at the Baylor College
of Medicine who is not connected to the research.
"The difference between humans and rats is that it isn't
as easy to get humans to exercise," Klann added. "Put
an exercise wheel in a rat cage and a rat will zoom around
on that thing all the time, unless it's sleeping. But
putting an exercise machine in your family room doesn't
mean you're going to use it."
The next step in the research is to determine which natural
chemicals and mechanisms are triggered by exercise to
fight oxidative stress, and to test whether reducing the
stress actually improves brain function.
"By age 50 almost everyone has mild memory deficits,"
Foster said. "We forget where we put the keys or jumble
the names of our kids. If these losses increase, then
we run into problems. We want to prevent that. Certainly
exercise with a doctor's permission is good at any time
of life. Light walking, burning 150 calories at a time,
may be beneficial in changing the enzymes within our bodies
that protect us from free radicals and remove damaged
molecules."
- More articles
on Exercise
Reference
Source 125
November
15, 2005
