MONDAY, March 7 (HealthDay News) -- People who suffer a stroke
and also have an irregular heart rhythm called atrial fibrillation
may be at greater risk of developing dementia than stroke survivors
without the heart condition, British researchers report.
The likelihood of atrial fibrillation increases with age, and it
is a significant risk factor for stroke. More than 2 million
Americans have the condition, according to the study, published in
the March 8 issue of
"We know that atrial fibrillation is a common arrhythmia in older patients, but it has been unclear whether the arrhythmia is a major risk factor for dementia," said researcher Dr. Yoon K. Loke, a senior lecturer in clinical pharmacology at the University of East Anglia in Norwich, U.K.
"In the stroke population, atrial fibrillation appears to have a major role in contributing to dementia, and clinicians should concentrate their efforts on tackling this, in addition to any associated cardiovascular risk factors," he added.
For the study, Loke and colleagues gathered data on 46,637
people, average age 72, who took part in 15 separate studies.
This is a method known as a meta-analysis in which researchers
pull out certain data from studies not necessarily designed to
evaluate the specific outcomes these researchers are interested in.
The goal is to identify any significant trends.
In this case, the pooled data showed that people who survive a
stroke and who also have atrial fibrillation are 2.4 times more
likely to develop dementia, compared with stroke survivors without
this irregular heart beat.
In all, about 25 percent of patients with stroke and atrial
fibrillation developed dementia during follow-up, the researchers
Strategies are needed to reduce this excess dementia risk in
stroke patients, Loke said. "This may include steps such as better
control of the arrhythmia and more effective prevention of
The researchers were unable to determine whether people with
atrial fibrillation but no stroke history are at a greater risk for
dementia. "In wider populations that involve patients who do not
have stroke, atrial fibrillation does not seem to be a major
contributor to the risk of dementia," Loke said.
Many factors other than atrial fibrillation probably contribute
to dementia, he said. "A targeted or focused approach on management
of atrial fibrillation may not help to reduce the burden of
dementia," he added.
Commenting on the study, Dr. Larry B. Goldstein, a professor of
medicine and director of the Duke Stroke Center at Duke University
Medical Center, said that "there was considerable variability among
the included studies."
The relationship between atrial fibrillation and dementia in
those with stroke is not unexpected, Goldstein said. Strokes that
result from heart problems tend to be larger and more frequently
involve the left middle cerebral artery, leading to aphasia (damage
to the brain area that controls language), which can complicate
cognitive testing, he explained.
"The meta-analysis did not control for these factors, although two of the studies excluded those with aphasia," Goldstein said.
Dr. Richard B. Libman, chief of the division of vascular
neurology at Long Island Jewish Medical Center in New Hyde Park,
N.Y., added that this study is not conclusive, but appears to
suggest a connection.
"If it turns out that atrial fibrillation is associated with dementia only because atrial fibrillation is a cause of stroke, then we do whatever we can to prevent strokes in people who have atrial fibrillation," he said.
But it's possible that atrial fibrillation by itself could play
a role in dementia. "That's a little trickier," Libman noted. The
goal of treatment then would be to control the arrhythmia through
drugs or medical procedures, he said.
Libman said a meta-analysis has limitations, because the various
studies use different methods. "You can't tease out relationships
always by combining data," he said. "All you can do is get a
general idea that perhaps will guide further research."
For more information on stroke, visit the
U.S. National Library of Medicine.
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