July 7, 2009
Men and women with a heart rhythm problem called atrial fibrillation are at increased risk of Alzheimer's disease, a new study reports. The findings add to a growing body of evidence that links heart and brain health.
Atrial fibrillation, or "A-fib," strikes more than two million Americans. It is especially common in seniors, affecting one in nine people over 80. It occurs when the upper chambers of the heart quiver erratically instead of beating steadily. Young people may have the disorder as well but not even know it because atrial fibrillation may have few or no symptoms. Doctors do an electrocardiogram, or ECG, to diagnose the condition.
Other studies have shown that heart risks like high cholesterol, hardening of the arteries and other forms of cardiovascular disease are linked to an increased risk of Alzheimer's. This study shows that heart rhythm problems may predispose a person to dementia as well. Doctors from the Intermountain Medical Center in Salt Lake City presented the findings at the Heart Rhythm Society medical conference in Boston on May 15.
The Utah researchers studied medical files from more than 37,000 men and women and found that overall, those with atrial fibrillation were 44 percent more likely to develop Alzheimer's and other forms of dementia that people without the heart problem. People younger than 70 with A-fib were more than twice as likely to develop Alzheimer's than their heart-healthy peers.
In addition, those with Alzheimer's who also had A-fib were 61 percent more likely to die over the five-year course of the study than those without the heart problem.
Previous studies have shown that patients with A-fib are at higher risk for some types of dementia, including those related to poor blood flow in the brain. "But to our knowledge, this is the first large-population study to clearly show that having atrial fibrillation puts patients at greater risk for developing Alzheimer's disease," said Intermountain Medical Center cardiologist T. Jared Bunch, M.D., the study's lead researcher.
One reason why A-fib may lead to brain problems is that the condition causes blood to collect and stay put for a while and possibly clot. If the clot leaves the heart, it can lodge in the brain and cause a stroke or series of "mini"-strokes that cause brain cells to die.
No one knows what causes A-fib. Recent research suggests some cases may be inherited. Stress, smoking, heavy drinking, obesity and a range of illnesses also raise the risk of developing the condition and the likelihood that it will be more difficult to treat.
The study authors say more research is needed to explore further the relationship between A-fib and the development of Alzheimer's disease.
"Now that we've established this link, our focus will be to see if early treatment of A-fib can prevent dementia or the development of Alzheimer's disease," said cardiologist John Day, M.D., director of heart rhythm services at Intermountain Medical Center and a co-author of the study.
May 15, "Heart Rhythm 2009," the annual scientific sessions of the Heart Rhythm Society, Boston.