Abnormal Heart Rhythm Linked to Alzheimer's
FRIDAY April 16, 2010 -- People with atrial fibrillation, a form of abnormal heart rhythm, are more likely than others to develop dementia, including Alzheimer's disease, a new study finds.
The presence of atrial fibrillation also predicted higher death rates in dementia patients, especially among younger patients in the group studied, meaning under the age of 70.
"This leaves us with the finding that atrial fibrillation, independent of everything else, is a risk factor [for dementia]," said Dr. Gary Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York City. "This is adding one more brick in the road toward understanding that cardiovascular disease is a major risk factor for dementia."
"Alzheimer's disease, in particular, is one where we don't quite understand the risk factors and what causes it, so studies [like this] that try to investigate the causative effect will help us understand that and ultimately design therapies and approaches to prevent or minimize disease," added Dr. Jared Bunch, lead author of a study appearing in the April edition of the HeartRhythm Journal and a cardiologist/ electrophysiologist with Intermountain Medical Center in Murray, Utah.
This study, however, was not specifically set up to establish a direct cause-and-effect relationship.
The authors looked at 37,025 patients without atrial fibrillation or dementia, aged 60 to 90, over a five-year period.
Individuals who developed atrial fibrillation had a higher risk of all types of dementia, even when other risk factors were taken into account. Alzheimer's disease is by far the most common form of dementia.
More surprising was that those in the younger group -- under age 70 -- who had atrial fibrillation had the highest risk of developing dementia, even though dementia is normally associated with aging. People in this group were also at a 38 percent higher risk of dying.
Among the 764 patients who developed both conditions, diagnosis of atrial fibrillation usually happened first, followed by a diagnosis of dementia. Sometimes the diagnoses occurred simultaneously, the researchers noted.
The authors hypothesized that both atrial fibrillation and dementia may arise from the same risk factors, such as hypertension. Another possibility is that atrial fibrillation increases inflammation, and dementia has been shown to be higher in people with signs of systemic inflammation. Investigating whether treatment of hypertension and/or inflammation in AF patients might help curb the risk of dementia is an area of future study, the researchers added.
"From a public health perspective, the best thing we can do to decrease the coming epidemic of Alzheimer's disease is to do a much better, more aggressive job of helping people with heart disease," Kennedy said. "That means diet and exercise, of course -- everyone knows that. We need to look at obstacles that people encounter beyond their own behavior, obstacles we put up environmentally in the workplace, in the school, that keep people from having better diet and exercise. A heart-healthy diet and lifestyle are really the best means we have available to prevent dementia."
About 2.2 million Americans have atrial fibrillation, while an estimated 5.5 million suffer from Alzheimer's.
Posted: April 2010