Increase Daily Movement to Avoid
Age-Related Brain Shrinkage
February 26, 2016
Story at-a-glance
-
Physical exercise decreases risk of age-related brain
shrinkage, and increases cognitive abilities by
promoting neurogenesis — your brain’s ability to adapt
and grow new brain cells
Low physical fitness correlates to smaller brain volume
over time
Any movement that strengthens your leg muscles, such as
walking, leg extensions, and squats, helps protect your
brain against cognitive decline and memory loss
By Dr. Mercola
Scientists have linked physical
exercise to brain health for many years.
In fact, there’s compelling evidence that physical exercise helps
build a brain that not only resists shrinkage, but increases
cognitive abilities1
by promoting neurogenesis, i.e. your brain’s ability to adapt and
grow new brain cells.
In essence, physical activity produces biochemical changes that
strengthen and renew not only your body but also your brain —
particularly areas associated with memory and learning.
The converse is also true. Researchers have shown a sedentary
lifestyle correlates to brain shrinkage, which increases your risk
of memory loss and other cognitive problems.
“A new study3
published ... in Neurology links low levels of physical fitness
in midlife to lower brain tissue volume two decades later. These
findings affirm the role physical fitness plays in protecting
the brain as we age.
‘Brain volume is one marker of brain aging...and this
atrophy is related to cognitive decline and increased risk for
dementia,’ says lead author Nicole Spartano ...
‘So it is important to determine the factors — especially
modifiable factors, such as fitness — that contribute to brain
aging.’”
Low Physical Fitness Correlates to Smaller Brain Volume
Exercise helps protect and improve your brain function by
improving and increasing blood flow to your brain; increasing
production of nerve-protecting compounds; improving development and
survival of neurons; and reducing damaging plaques in your brain.
Over time, the cumulative effects help slow down the rate at
which your brain ages.
In this study4,5
data on more than 1,580 participants in the Framingham Heart Study
were analyzed. At the outset, all were free of dementia and heart
disease. Each person took a treadmill test, which was then
duplicated 20 years later. An MRI scan was also done during the
follow-up.
The participants’ exercise capacity was measured by the time they
could run on the treadmill before reaching a target heart rate. In
the end, lower levels of physical fitness correlated with smaller
brain volume. As noted in the featured article:
“For every eight units lower a person scored on the
treadmill test, the smaller their brain volume was two decades
later. An eight-unit interval represented a reduction in brain
volume that was equivalent to one year of aging.
The researcher also observed that participants who had an
especially high heart rate and blood pressure during the most
vigorous exercise had notably smaller brain volumes two decades
later.”
Exercise Boosts Brain Growth and Regeneration
As mentioned earlier, your brain is capable of rejuvenating and
regenerating itself throughout your life. This information is
completely contrary to what was known when I was in medical school
in the ‘70s.
At that time, it was believed that once neurons die, nothing
could be done about it. Hence deterioration and progressive memory
decline was considered a more or less inevitable part of aging.
Today, we know there’s nothing “inevitable” about age-related
cognitive decline at all.
In his book “Spark: The Revolutionary New Science of Exercise and
the Brain,” psychiatrist Dr. John J. Ratey discusses the evidence
showing that exercise actually produces large cognitive gains and
helps fight dementia.
Research6
has also shown that those who exercise maintain a greater volume of
gray matter specifically in the hippocampal region; an area of your
brain associated with memory.
Exercise also helps preserve gray and white matter in your
frontal, temporal, and parietal cortexes, which also helps prevent
cognitive deterioration.7,8
Perhaps most exciting of all, brain shrinkage can be quelled even if
you start exercising later in life.
For example, one observational study9
that followed more than 600 seniors, starting at age 70, found that
those who engaged in the most physical exercise showed the least
amount of brain shrinkage over a follow-up period of three years.
For Optimal Health, Get More Non-Exercise Movement Into Your Day
Eighty percent of Americans fail to meet the recommended amount
of exercise, which is 2.5 hours of moderate-intensity activity or
1.25 hours of vigorous-intensity activity each week, along with
twice weekly
strength-training workouts. These are the “official” U.S.
government exercise recommendations.
If you fall into this category, take heart, because there’s
compelling evidence to suggest that
non-exercise movement may actually be even more important than a
regular exercise program. Even if you’re a fit athlete who exercises
regularly, you may still endanger your health simply by
sitting too much.
Research has demonstrated that six hours of
uninterrupted sitting counteracts the positive health benefits
of one hour of exercise, so the foundation for good health is
relatively constant or regular movement.
Upon this foundation you can then build your fitness to
increasingly higher levels by adding on a few workout
sessions each week. For maximum benefits with a minimal time
investment, high-intensity interval training (HIIT)
is an ideal add-on, two or three times a week.
Standing and Walking — Two Key Components of Non-Exercise Movement
You can look at non-exercise movement as a two-part equation
involving:
Avoiding sitting as much as possible during the day. Just
standing up produces beneficial biological effects, including
improved blood flow, which is as important for your brain as it
is for the rest of your body.
If you’re an office worker, consider investing in a stand-up
desk. Ideally, employers would provide a stand-up desk option to
improve the health of their employees, which is what I did in my
Chicago office. I also use a stand-up desk in my home office
(see video above).
Walking more, ideally 7,000 to 10,000 steps or about one
hour per day. A fitness tracker can be a great tool to help you
reach your goal on a daily basis, and every step counts.
There are many creative ways to get more walking into each
day, from parking your car further away from the front door of
your office; taking the stairs instead of the elevator;
conducting walking meetings; or walking rather than driving when
going out to lunch.
Walking Helps Protect Your Ability to Think and Learn
A recent study that supports these recommendations actually
showed that when you work your leg muscles, your cognitive function
benefits. According to the authors, simply walking more could help
maintain brain function well into old age. This study10,11,12,13
followed 324 female twins, aged 43 to 73, for a decade. Cognitive
function such as learning and memory was tested at the outset and at
the conclusion of the study.
“The researchers found that leg strength was a
better predictor of brain health than any other lifestyle factor
looked at in the study. Generally, the twin with more leg
strength at the start of the study maintained her mental
abilities better and had fewer age-related brain changes than
the twin with weaker legs ...
‘It's compelling to see such differences in cognition
[thinking] and brain structure in identical twins, who had
different leg power 10 years before,’ [lead author Claire]
Steves, Ph.D. added. ‘It suggests that simple lifestyle changes
to boost our physical activity may help to keep us both mentally
and physically healthy.’"
The study on twins is said to be the first showing a specific
link between leg power and cognition in normal, healthy people, and
this is great news, as your leg muscles are among the largest in
your body and can be easily worked, either through seated leg
exercises, or by standing and walking.
Weighted Leg Extensions Boost Memory
Another study15
linking leg strength to cognitive gains was published in 2014. Here,
working out the leg muscles by doing just 20 minutes of weighted leg
extensions enhanced long-term memory by about 10 percent. In this
experiment, 46 volunteers were randomly assigned to one of two
groups — one active, and one passive. Initially, all of the
participants viewed a series of 90 images. Afterward, they were
asked to recall as many images as they could.
Next, the active group was told to do 50 leg extensions at
personal maximum effort using a resistance exercise machine. The
passive participants were asked to let the machine move their leg,
without exerting any personal effort.
Two days later the participants returned to the lab, where they
were shown a series of 180 pictures — the 90 original photos, plus
90 new ones. Interestingly, even though it was two days since they
performed the leg extensions, those in the active group had markedly
improved image recall. The passive control group recalled about 50
percent of the original photos, whereas the active group remembered
about 60 percent of the previously shown images.
“Our study indicates that people don’t have to dedicate
large amounts of time to give their brain a boost,’ says Lisa
Weinberg ... who led the project. Although the study used weight
exercises ... resistance activities such as squats or knee bends
would likely produce the same results. In other words, exercises
that don’t require the person to be in good enough to shape to
bike, run, or participate in prolonged aerobic exercises ...”
How Muscle Strength Can Translate Into Brain Health
So what might account for these findings? We know that improved
blood flow increases oxygenation to your brain, which of course has
potent benefits, but what is it about muscle strength that
influences brain function? Interestingly, previous research has
demonstrated that exercise prompts the release of various hormones,
growth factors, and proteins — a number of which have a direct
impact on your brain health:
Brain-derived neurotrophic factor (BDNF) is a growth factor
that influences both muscles and neurons. In your neuromuscular
system, BDNF protects neuromotors from degradation. (The
neuromotor is the most critical element in your muscle. Without
the neuromotor, your muscle is like an engine without ignition.
Neuromotor degradation is part of the process that explains
age-related muscle atrophy).
In your brain, BDNF triggers chemicals that promote neural
health and directly benefit cognitive functions, including
learning.
Muscle regulatory factors (MRFs) signal brain stem cells and
muscle satellite cells to convert into new neurons and new
muscle cells respectively.
Exercise lowers the activity of bone-morphogenetic protein
(BMP). BMP slows the production of new brain cells, so by
dampening its activity, brain cells can more easily be renewed.
Exercise also increases Noggin, a brain protein that acts as
a BMP antagonist. The more Noggin present in your brain, the
less BMP activity there is, and the more stem cell divisions and
neurogenesis (production of new brain cells) takes place.
Exercise also has a powerful molecular biological action, as
it is one of the most potent stimulators of mitochondrial
biogenesis through the signaling mechanisms of AMPK and SIRT1.
To Optimize Your Health and Longevity, Stay in Motion
The type of exercise program that will benefit your brain is
identical to the one that will benefit the rest of your body,
starting with non-exercise movements like standing and walking. Keep
in mind that there are many muscle-strengthening exercises you can
do without having to switch out of your work clothes. You can easily
pull off a few
squats right by your desk, or do a few walking lunges when
moving from room to room for example.
Dementia is on the rise, but there’s a lot you can do to prevent
it. Staying active is one component. Eating right and avoiding toxic
exposures are two others. For a refresher on the dietary and
lifestyle modifications shown to protect against and possibly even
treat cognitive decline, please see my previous article on
Alzheimer’s prevention. You don’t have to become a statistic,
and every step you take — both literally and figuratively — will
improve your odds.