The abnormal heartbeat called atrial fibrillation is associated with later development of Alzheimer's disease, a large-scale study finds.
There are three possible explanations for the relationship, each of which could lead to early treatment aimed at preventing the dementia, said study author Dr. T. Jared Bunch, an electrophysiologist at Intermountain Healthcare in Salt Lake City. His group was to present the finding Friday in Boston at the Heart Rhythm Society's annual meeting.
The study used data on 37,000 people treated at the 20 hospitals run by Intermountain Healthcare in Utah, Idaho and Wyoming. It found that people with atrial fibrillation, in which the upper chambers of the heart can quiver uselessly rather than pumping blood, were 44 percent more likely to develop dementia over a five-year period than those without the heart disorder.
The association was especially strong for people under the age of 70. Those with atrial fibrillation were 130 percent more likely to develop Alzheimer's disease.
And the combination could be lethal. The study found that people with atrial fibrillation and dementia were 61 percent more likely to die during the five-year study period.
Earlier studies have shown that people with atrial fibrillation are at higher risk of some forms of dementia, Bunch said. But this was the first large-scale population study to show an association of atrial fibrillation and increased risk of developing Alzheimer's disease, he said.
"We can't say yet that it is causal," Bunch said of the relationship. "We can say it is related to heightened risk. The next step is to look at the mechanistic association, to understand how one predisposes to the other."
One possibility, he said, is that both problems are related to high blood pressure, which could cause heart function to deteriorate so that blood flow to the brain is reduced, starving brain cells of oxygen. Early and intensive treatment of high blood pressure thus might prevent dementia, Bunch said.