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 While past research suggests that brain shrinkage may be an
unavoidable part of aging, the new findings add inactivity to a
growing list of factors like smoking, obesity, diabetes and high
blood pressure that are thought to accelerate the process.
“We found that poor fitness in midlife was linked to more rapid
brain aging two decades later,” said lead author Nicole Spartano of
Boston University School of Medicine.
“This message may be especially important for people with heart
disease or at risk for heart disease, in whom we found an even
stronger relationship between fitness and brain aging,” Spartano
added by email.
The study included 1,583 people enrolled in the long-running
Framingham Heart Study who took a treadmill test to assess their
fitness levels when they were 40 years old on average, and were free
of dementia and heart disease at that time.
Almost two decades later, researchers put them back on the
treadmill, and also did magnetic resonance imaging (MRI) scans of
their brains. At this point, they were around 58 years old.
In that first treadmill test, 89 percent of the participants
achieved their target heart rate, a level slightly below what
researchers estimated to be their peak capacity.
At this point, participants had an average estimated exercise
capacity of 39 milliliters of oxygen per kilogram of body mass per
minute (mL/kg/min), which is also known as “peak VO2,” and
represents the maximum amount of oxygen the body is capable of using
in one minute. The score of 39 is considered fairly typical for
nonatheletes in their 40s.
Spartano and colleagues found that two decades later, people with
below average fitness in the first test had smaller total brain
volume than the others. Each 8 mL/kg/min of exercise capacity below
the average performance level in the first test was associated with
enough reduction in brain volume by the end of the study to amount
to two extra years of brain aging, according to the results in
Neurology.
People whose blood pressure and heart rate surged more during the
first treadmill test – another indication of poor fitness – were
also more likely to have smaller brain volumes two decades later.
Over the course of the study, the ranks of people with hypertension
surged to 28 percent from 9 percent.
One limitation of the study is that the treadmill test at the end
was easier than the one participants did at the start. As a result,
researchers couldn’t estimate maximum exercise capacity.
The study also wasn’t designed to prove that poor fitness erodes
brain volume or directly causes cognitive decline.
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Even so, the findings should encourage people to exercise earlier in
life, and often, said Sandra Bond Chapman, founder and chief
director of the Center for BrainHealth at the University of Texas in
Dallas.
“The take-home message is a familiar one – an ounce of prevention is
worth a pound of cure,” Chapman, who wasn’t involved in the study,
said by email.
People who haven’t started exercising by 40 can still get moving,
Chapman added. Some sedentary people 50 and older who start workout
routines may see improved cognition and neural health after as
little as 6 weeks of aerobic exercise.
Findings from the current study offer more evidence that the choices
people make in their 40s can impact brain health later in life, said
Scott Hayes, a researcher at Boston University and the Memory
Disorders Research Center at VA Boston Healthcare System.
“Given that most people fail to meet the minimum recommended
requirements for physical activity, this could provide some
motivation for those middle-aged adults to become more physically
active,” Hayes, who wasn’t involved in the study, said by email.
Each week, adults need at least 2.5 hours of moderate intensity
aerobic activity like brisk walking and a minimum of two muscle
strengthening workouts.
“Ideally, one would do aerobic and strength training coupled with
stabilization exercises to improve balance and coordination, as well
as flexibility training,” Hayes added.
SOURCE: http://bit.ly/1f4kQ99 Neurology, online February 10, 2016.
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