"Problems with memory and thinking are common for people as they get older. Our study shows that on average, problems with memory and thinking may start earlier or get worse more quickly in people who have atrial fibrillation," said study author Evan L. Thacker, PhD, of the University of Alabama at Birmingham. "This means that heart health is an important factor related to brain health."

The study involved people age 65 and older from four communities in the United States who were enrolled in the Cardiovascular Health Study. Participants did not have a history of atrial fibrillation or stroke at the start of the study. They were followed for an average of seven years, and received a 100-point memory and thinking test every year. People who had a stroke were not included in this analysis after the stroke. Of the 5,150 participants, 552, or about 11 percent, developed atrial fibrillation during the study.

The study found that people with atrial fibrillation were more likely to experience lower memory and thinking scores at earlier ages than people with no history of atrial fibrillation. For example, from age 80 to age 85 the average score on the 100-point test went down by about 6 points for people without atrial fibrillation, but it went down by about 10 points for people with atrial fibrillation.

For participants ages 75 and older, the average rate of decline was about three to four points faster per five years of aging with atrial fibrillation compared to those without the condition.

"This suggests that on average, people with atrial fibrillation may be more likely to develop cognitive impairment or dementia at earlier ages than people with no history of atrial fibrillation," Thacker said.

Thacker noted that scores below 78 points on the 100-point test are suggestive of dementia. People without atrial fibrillation in the study were predicted on average to score below 78 points at age 87, while people with atrial fibrillation were predicted to score below 78 points at age 85, two years earlier.

"If there is indeed a link between atrial fibrillation and memory and thinking decline, the next steps are to learn why that decline happens and how we can prevent that decline," said Thacker.

The study was supported by the National Heart, Lung, and Blood Institute, the National Institute of Neurological Disorders and Stroke and the National Institute on Aging.