MONDAY, March 13, 2023 (HealthDay News) -- The common irregular heartbeat known as atrial fibrillation (a-fib) may increase the risk of dementia, a new study suggests.

Researchers found that people newly diagnosed with a-fib had a 13% higher risk of developing dementia, the progressive loss of memory and thinking skills. The risk was even higher (65%) among those who developed a-fib before age 65 and in people who did not have chronic kidney disease (20%).

"The health consequences of atrial fibrillation may be broader than originally recognized in certain individuals," said lead researcher Dr. Nisha Bansal, a professor of medicine at the University of Washington, in Seattle. "A personalized approach is needed to help inform patients of the consequences of their atrial fibrillation."

A-fib is the most common type of heart arrhythmia (irregular heartbeat), Bansal said.

"Until now, atrial fibrillation has been strongly linked with the risk of stroke, and the possible link with dementia has been unclear," she said.

A-fib is a rapid, disorganized beating of the heart's upper chamber. Episodes can come and go, or may be persistent. It can lead to blood clots that travel to the brain, causing a stroke.

This study doesn't prove that a-fib causes dementia, only that there appears to be a link between the two. Bansal emphasized that not everyone who has a-fib will develop dementia.

"If atrial fibrillation is also associated with dementia, it has important clinical and public health implications when it comes to the management of patients," Bansal said. "More research is needed to understand the biological mechanisms that explain this association as well as whether treatment of atrial fibrillation might lower the risk of dementia."

For the study, Bansal and her colleagues collected data on nearly 197,000 patients from the Kaiser Permanente health system in California. Half had been recently diagnosed with a-fib. They were compared with a like number without the condition.

The researchers took steps to offset the influence of other medical conditions known to increase dementia risk. Bansal, a kidney specialist, said it was a surprise to find a greater risk among those without kidney disease and in younger patients.

Her team will try next to better understand the biological mechanisms linking a-fib and dementia, and how different treatments for irregular heartbeat factor in.

It's not known why a-fib might cause dementia, said Dr. Laurence Epstein, system director of electrophysiology at Northwell Health in Manhasset, N.Y., who reviewed the findings.

"One of the things that we've always struggled with is: What is the potential reason a-fib leads to an increased risk of dementia?" he said.

A lot of people think a-fib may not only affect the heart but blood vessels throughout the body, which might increase the risk of dementia. “It’s a question this study doesn’t answer,” he said.

"One thing people have thought about, since we know that a-fib leads to an increased risk of stroke, is could there be subclinical strokes or micro-strokes going to the brain that may not manifest themselves as a clear clinical stroke but over time, lead to dementia?" he suggested. "That's one concern we've always had."

It's not clear whether a-fib causes dementia or is a marker for other disease processes that increase the risk for dementia, Epstein said.

The best way to avoid developing a-fib is to maintain a normal weight and blood pressure, avoid sleep apnea, get plenty of exercise and eat a healthy diet, he advised.

"Managing those things aggressively may reduce the incidence of atrial fibrillation," Epstein said. "But interestingly, those are all the same things that if you manage aggressively also reduce your risk of dementia."

He said another open question is whether treating a-fib — by keeping the heart in a normal (sinus) rhythm — will lower dementia risk.

Medications can help maintain a normal heart rhythm, but they don't work for everybody and can have serious side effects, Epstein said.

The other option is ablation, a treatment in which heat is used to deaden the areas in the heart that are causing a-fib. This can be effective in the long term but it doesn't work for everyone, Epstein noted.

The findings were published online March 8 in the Journal of the American Heart Association.

More information

For more on atrial fibrillation, head to the American Heart Association.

SOURCES: Nisha Bansal, MD, professor, medicine, University of Washington, Seattle; Laurence Epstein, MD, system director, electrophysiology, Northwell Health, Manhasset, N.Y.; Journal of the American Heart Association, March 8, 2023, online