Study of more than 37,000 patients shows relationship between atrial fibrillation and development of Alzheimer's disease

Researchers at Intermountain Medical Center in Salt Lake City believe that they have made a breakthrough connection between atrial fibrillation, a fairly common heart rhythm disorder, and Alzheimer's disease, the leading form of dementia among Americans.

In a study presented Friday, May 15, at "Heart Rhythm 2009," the annual scientific sessions of the Heart Rhythm Society in Boston, researchers unveiled findings from the study of more than 37,000 patients that showed a strong relationship between atrial fibrillation and the development of Alzheimer's disease.

The study, which drew upon information from the Intermountain Heart Collaborative Study, a vast database from hundreds of thousands of patients treated at Intermountain Healthcare hospitals, found:

• Patients with atrial fibrillation were 44 percent more likely to develop dementia than patients without the heart disorder.

• Younger patients with atrial fibrillation were at higher risk of developing all types of dementia, particularly Alzheimer's. Atrial fibrillation patients under age 70 were 130 percent more likely to develop Alzheimer's.

• Patients who have both atrial fibrillation and dementia were 61 percent more likely to die during the study period than dementia patients without the rhythm problem.

• Younger atrial fibrillation patients with dementia may be at higher risk of death than older AF patients with dementia.

Intermountain Medical Center cardiologist T. Jared Bunch, M.D., the study's lead researcher, presented the findings at the scientific session.

"Previous studies have shown that patients with atrial fibrillation are at higher risk for some types of dementia, including vascular dementia. 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 Dr. Bunch.

Alzheimer's is a devastating brain disease affecting approximately 5.3 million Americans. It is the most common form of dementia (a general term for life-altering loss of memory and other cognitive abilities), and accounts for 60-80 percent of all dementia cases. Today, it is the sixth leading cause of death in the United States.

Currently, the known risk factors for Alzheimer's are age, family history and genetics, though injury may also be linked with the disease. Heart health has long been suspected to play a role, but has not been linked. The Intermountain Medical Center study bolsters that connection.

"The study shows a connection between atrial fibrillation and all types of dementia," said Bunch. "The Alzheimer's findings — particularly the risk of death for younger patients — break new ground."

Atrial fibrillation is the most common heart rhythm problem, affecting about 2.2 million Americans. It occurs when the heart beats chaotically, leading blood to pool and possibly clot. If the clot leaves the heart, a stroke can result.

The Intermountain Medical Center study looked at five years of data for 37,025 patients. Of that group, 10,161 developed AF and 1,535 developed dementia during the study period.

The study authors say more research is needed to explore further the relationship between atrial fibrillation and the development of Alzheimer's disease.

"Now that we've established this link, our focus will be to see if early treatment of atrial fibrillation can prevent dementia or the development of Alzheimer's disease," says cardiologist John Day, M.D., director of heart rhythm services at Intermountain Medical Center and a co-author of the study.

Intermountain Medical Center is the flagship medical and research facility for Intermountain Healthcare, a nationally-recognized nonprofit system of hospitals, surgery centers, doctors, and clinics that serve the medical needs of patients throughout the Intermountain West.