Large Kaiser Permanente study finds modestly increased risk, with stronger association in younger, healthier people
By Sue Rochman
People who have been diagnosed with atrial fibrillation are known to have an increased risk of developing other heart problems. A new Kaiser Permanente study suggests they may also be at increased risk for dementia.
The researchers found that people with atrial fibrillation, the most common type of irregular heartbeat, had a 13% greater risk of being diagnosed with dementia. The association was stronger in people diagnosed with atrial fibrillation before age 65 and in those who did not have chronic kidney disease. No meaningful differences were seen by sex, race, or ethnicity.
“We know that atrial fibrillation is one of the strongest risk factors for ischemic stroke but whether atrial fibrillation increases the risk of developing dementia independent of having a stroke has been unclear,” said senior author Alan S. Go, MD, a senior research scientist at the Kaiser Permanente Division of Research. “If it does, it would have important clinical and public health implications given that atrial fibrillation is becoming more common nationally and internationally.”
The study, published in the Journal of the American Heart Association, included close to 197,000 patients at Kaiser Permanente Northern California (KPNC) and Kaiser Permanente Southern California (KPSC). Half of the patients in the study had recently been diagnosed with atrial fibrillation. The other half were similar in age and health to those patients but did not have an atrial fibrillation diagnosis. During about 3 years of follow-up, the research team from KPNC, KPSC, and the University of Washington reviewed all the patients’ medical records to identify those who had been diagnosed with any type of dementia, including Alzheimer’s disease which is the most common type. The researchers also took into account whether these patients had had a stroke, which greatly increases the risk of dementia developing.
The findings are expected to contribute to ongoing discussions on ways to advance research in this area. “Our study within a very large, community based, diverse population is an important contribution to our understanding of atrial fibrillation and dementia,” said first author Nisha Bansal, MD, a professor at the University of Washington School of Medicine. “Our findings suggest that atrial fibrillation on its own is modestly associated with a higher risk of dementia, and that the risk is relatively higher in patients who do not have other chronic illnesses, like chronic kidney disease, that become more common as people age.”
Atrial fibrillation increases risks for stroke, heart failure, other heart-related problems, and dying earlier. The precise reason why atrial fibrillation may increase risk for dementia is not known. Previous studies that have looked at associations between atrial fibrillation and dementia have had mixed results.
“Based on our study, there is clearly a need for more research to help us better understand the biological mechanisms that contribute to this association and to help us identity treatments or strategies to help prevent or slow progression to dementia in patients who develop atrial fibrillation,” said Go.
The study was funded by the National Heart, Lung and Blood Institute.
Co-authors include Leila R. Zelnick, PhD, from the University of Washington, Seattle; Jaejin An, PhD, and Teresa N. Harrison, SM, of the Kaiser Permanente Department of Research and Evaluation; Ming-Sum Lee, MD, PhD, of the Kaiser Permanente Los Angeles Medical Center; Daniel E. Singer, MD, of Harvard University; and Dongjie Fan, MS, of the Division of Research.
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About the Kaiser Permanente Division of Research
The Kaiser Permanente Division of Research conducts, publishes and disseminates epidemiologic and health services research to improve the health and medical care of Kaiser Permanente members and society at large. It seeks to understand the determinants of illness and well-being, and to improve the quality and cost-effectiveness of health care. Currently, DOR’s 600-plus staff is working on more than 450 epidemiological and health services research projects. For more information, visit divisionofresearch.kaiserpermanente.org or follow us @KPDOR.