While stroke has long been linked to a heightened risk of dementia,
particularly in older adults, the exact magnitude of the increased
risk hasn't been consistent across previous studies investigating
this connection. For the current study, researchers pooled data from
48 previous studies with a total of 3.2 million participants
People who had a recent stroke were 2.2 times more likely to develop
dementia than people who never had a stroke, the analysis found. And
a history of stroke was associated with a 69 percent higher chance
of developing dementia.
"These findings stress the importance of protecting the blood supply
to the brain in order to protect against dementia," said senior
study author Dr. David Llewellyn of the University of Exeter Medical
School in the UK.
"By focusing upon lifestyle factors that are within our control we
can reduce our risk of developing dementia as a result of stroke,"
Llewellyn said by email.
"Quit smoking, eat a Mediterranean diet, get physically and mentally
active, and drink less alcohol," Llewellyn advised. "Most people who
have a stroke do not develop dementia as a result, so improvements
in lifestyle after stroke are also likely to be beneficial."
Alzheimer's disease is the most common cause of dementia among older
adults. The progressive brain disorder slowly erodes memory and
thinking skills and eventually leaves people unable to handle basic
tasks in daily life.
Previous research has linked so-called vascular risk factors,
including obesity, diabetes, smoking, high cholesterol and elevated
blood pressure, to higher odds of dementia, cognitive decline and
But it's been unclear whether these factors contribute indirectly by
restricting blood flow in the brain, or if they directly cause a
buildup of amyloid protein fragments that are linked to Alzheimer's.
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Certain characteristics of stroke, such as the location and the
extent of brain damage, may also influence the risk of dementia, the
study authors conclude. Men may also have a greater risk of dementia
after a stroke than women.
One limitation of the analysis is that the smaller studies varied in
design, duration, and how they assessed stroke and dementia,
researchers note in Alzheimer's & Dementia.
Still, the results add to a large body of evidence linking stroke to
dementia, said Dr. Andrew Budson, a researcher at the Veterans
Affairs Boston Healthcare System and Boston University School of
Medicine who wasn't involved in the study.
"Although not surprising, this important review emphasizes one way
that people can reduce their chances of developing dementia," said
Budson, author of "Seven Steps to Managing Your Memory: What's
Normal, What's Not, and What to Do About It."
"The take home message," he advised in an email, "is that you will
be less likely to develop dementia if you reduce your risk of stroke
by quitting if you smoke, keeping your sugars under control if you
have diabetes, taking medications for high blood pressure and
cholesterol as prescribed, losing weight if you are obese or
overweight, eating a Mediterranean style diet, and engaging in
SOURCE: http://bit.ly/2NsZTOs Alzheimer's & Dementia, online August
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