July 16, 2016
The way people walk appears to
speak volumes about the way they think, so much so that changes in an older
person’s gait appear to be an early indicator of cognitive impairment,
including Alzheimer’s disease.
Five studies presented at the
Alzheimer’s Association International Conference in Vancouver this month
provide striking evidence that when a person’s walk gets slower or becomes more
variable or less controlled, his cognitive function is also suffering.
Thinking skills like memory, planning activities or processing
information decline almost in parallel with the ability to walk fluidly, these
studies show.
In other words, the more trouble
people have walking, the more trouble they have thinking.
“Changes in walking may predate
actually observable cognitive changes in people who are on their way to
developing dementia,” said Molly Wagster, chief of the
National Institute on Aging’s behavioral and systems neuroscience branch.
Experts said the studies could lead to developing a relatively simple tool that
doctors could use to forecast, if not diagnose, possible Alzheimer’s disease.
“You can probably just watch them
walk down the hall in your office and look for people who are starting to show
deterioration in their gait and have no other explanation for it,” said William
Thies, the chief medical and scientific officer for the Alzheimer’s Association.
“If gait begins to deteriorate, we begin to have a conversation about how is
your memory.”
While scientists have studied gait
changes after a heart attack or stroke and in diseases like Parkinson’s, they have only recently begun
studying connections between walking and cognition. For decades, people thought
slower walking was just part of getting old, but research shows some changes in
gait signify problems that go beyond normal aging.
“It’s like driving a car — you
need an engine, a chassis and steering,” said Dr. Stephanie Studenski, an
expert on walking who was not involved in the dementia studies. The engine of
walking is the heart, lungs and blood, she said. The chassis is the muscles,
joints and bones.
And the steering is “the wiring —
the nervous system,” said Dr. Studenski, a geriatrician at the University of
Pittsburgh and the Pittsburgh Veterans Administration.
“People who are focused on
cognition largely never watch people move,” Dr. Studenski said. “The tests are
all done sitting down. But damage to the wiring is an important shared problem
of difficulty with thinking and difficulty with moving.”
The new studies were larger and
more detailed than previous research, and involved sophisticated measures of
changes in gait. Some used an electronic walkway, a long mat outfitted with
sensors that measure small differences in walking speed, cadence (the number of
steps per minute), the width of the stride and variability (how often the
person’s stride changes).
The studies screened out people
with arthritis or other physical problems, and
adjusted for height, age, weight and sex.
One study involved more than 1,100
elderly people in Basel, Switzerland. About a quarter of them were cognitively
healthy, while the others had mild cognitive impairment, considered a precursor
to dementia, or were in various stages of Alzheimer’s.
The participants walked normally
on the electronic walkway, and again while performing a cognitive task:
counting backward by two’s from 50, or naming animals.
One 72-year-old woman’s first
walking test betrayed no problems. But when she walked while counting backward
from 50, her gait worsened dramatically, said Dr. Stephanie Bridenbaugh, head
of the Basel Mobility Center.
“She teetered and wobbled on one
foot,” Dr. Bridenbaugh said. “She almost tipped to the side.” And “she didn’t
notice any of it,” she added. “She was mad that she didn’t remember more
numbers.”
Dr. Bridenbaugh referred her to
the memory clinic, where cognitive testing showed the woman already had mild
cognitive impairment.
Asking people to simultaneously
perform thinking and movement tasks revealed “deficits that you can’t see with
the naked eye,” Dr. Bridenbaugh said. It may be that the brain is already so
compromised that it cannot coordinate its circuits to efficiently manage such
“dual tasks.”
“A lot of times normal walking
looked normal, even in people with moderate Alzheimer’s, but if you look at
dual tasking, I can detect these problems,” said Dr. Bridenbaugh. Her research
consistently showed that people who walked more slowly or inconsistently did
worse on cognitive tests; the worst walkers had the most severe Alzheimer’s.
A large study at the Mayo Clinic
involved basic walking, not dual-tasking, but found a similar relationship,
said Dr. Rodolfo Savica, a neurologist at the clinic. Most of the 1,341
participants did not have dementia. They were evaluated twice, 15 months apart,
with tests of cognitive ability and walking.
Dr. Savica and his colleagues
found that on average a person who walked one meter per second slower on their
second test scored half a point lower on cognitive tests.
Slower walking was mostly strongly
linked to declines in “executive function,” the ability to plan and organize
activities. A study led by Dr. M. Arfan Ikram, a neuroepidemiologist at Erasmus
MC University Medical Center in Rotterdam, tried to connect particular changes
in gait with specific cognitive impairments.
More than 1,200 people with no
signs of dementia were asked to walk normally, to walk and turn around halfway
through, and to “tandem walk,” in which the heel of one foot is placed directly
in front of the toe of the previous foot. The subjects also were given
cognitive tests.
People with poor tandem walking
scored low on tests involving fine motor skills. People with lower cadences,
who took fewer steps per minute, did worse on tests of thinking speed. And
people whose walks were slower and more variable showed poor executive
function.
Dr. Ikram said no specific aspect
of walking was correlated to memory problems, perhaps suggesting “that memory
is purely a brain function which expresses itself only in cognition.”
Aside from suggesting that walking
may provide early clues that dementia is on its way, the studies may reinforce
the possibility that physical activity could help stave off
dementia. If slower and more erratic walking signifies neurological damage,
could exercises to improve fitness and coordination not only help people walk,
but also by help them think?
“Those are the ultimate
questions,” Dr. Ikram said. “Right now, we are really at the first step.”
Next, said Dr. Bridenbaugh, “what
we need is to use the information we have here and find a screening tool that
physical therapists and doctors can use to red flag those who have a mobility
problem. This should be basic. When your patient is in your office and you
listen to their heart, it should be basic to see how they walk.”
Video Link: http://nyti.ms/MtYp1U
http://www.nytimes.com/2012/07/17/health/research/signs-of-cognitive-decline-and-alzheimers-are-seen-in-gait.html?pagewanted=1&_r=0
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