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Study shows importance of exercise for those
at special risk for Alzheimer's
November 20, 2010--Physical activity promotes
changes in the brain that may protect
high-risk individuals against cognitive
decline, including development of
Alzheimer's disease, according to a new
study done at the University of
Wisconsin-Milwaukee (UWM).
J. Carson Smith, an assistant professor of
health sciences, included in the study both
people who carry a high-risk gene for
Alzheimer's disease, and other healthy older
adults without the gene.
"Our study suggests that if you are at genetic
risk for Alzheimer's disease, the benefits
of exercise to your brain function might be
even greater than for those who do not have
that genetic risk," says Smith.
While evidence already shows that physical
activity is associated with maintenance of
cognitive function across a life span, most
of this research has been done with healthy
people, without any consideration of their
level of risk for Alzheimer's, says Smith.
A team of researchers compared brain activation
during memory processing in four separate
groups of healthy 65- to 85-years-olds.
The level of risk was defined by whether an
individual carried the apolipoprotein
E-epsilon4 (APOE–ϵ4)
allele. Physical activity status was defined
by how much and how often the participants
reported physical activity (PA).
The study divided subjects
into Low Risk/Low PA, Low Risk/High PA, High
Risk/Low PA and High Risk/High PA.
Functional magnetic resonance imaging (fMRI)
was used to measure brain activation of
participants while they performed a mental
task involving discriminating among famous
people.
This test is very useful, says Smith, because
it engages a wide network called the
semantic memory system, with activation
occurring in 15 different functional regions
of the brain.
"When a person thinks about people – for
example, Frank Sinatra or Lady Gaga – that
involves several lobes of the brain,"
explains Smith.
In the study groups of those carrying the gene,
individuals who exercised showed greater
brain activity in memory-related regions
than those who were sedentary.
Perhaps even more intriguing, physically active
people with the gene had greater brain
activity than those who were physically
active but not gene carriers.
There are many physiological reasons why this
could be happening, Smith says. "For
example, people with this increased
activation might be compensating for some
underlying neurological event that is
involved in cognitive decline.". "Using more
areas of their brain may serve as a
protective function, even in the face of
disease processes."
