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.<
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