Midlife Atrial Fibrillation Linked to Dementia Risk

Atrial fibrillation diagnosed before age 70 years is associated with a 21% increased risk of developing dementia and a 36% higher risk for early-onset forms of the condition, according to the results of a large population-based study.

The findings strengthen a growing body of evidence linking atrial fibrillation and dementia, raising questions about optimal monitoring and intervention, said Julián Rodríguez García, MD, of Bellvitge University Hospital in Barcelona, Spain, who helped conduct the research.

“While this is a population-based study and does not establish causality, it strongly suggests that early detection of atrial fibrillation in younger patients, along with more proactive management of atrial fibrillation and its aggravating factors — such as cardiovascular risk factors — could be key to reducing dementia risk,” said Garcia, who presented the findings at the 2025 annual congress of the European Heart Rhythm Association.

Population-Based Data From Over 2.5 Million Adults

The study included more than 2.5 million men and women in Spain, aged 45 years or older without a history of dementia in 2007. García and his colleagues used anonymized data from the region’s primary care research database, which covers more than 80% of the population, to identify incident diagnoses of dementia between 2007 and 2021.

At baseline, 3.25% of participants had atrial fibrillation. Across the entire population, atrial fibrillation was a significant, yet weak, predictor of dementia, raising risk by just 4%.

Stratifying participants by age revealed a more striking association. Among people aged 45-50 years, those with atrial fibrillation were 3.4 times more likely to develop dementia than those without the arrythmia (hazard ratio, 3.4; 95% CI, 3.32-3.46).

Multivariate analysis showed patients diagnosed with atrial fibrillation before age 70 years had a 21% increased risk for dementia and a 36% increased risk for early-onset dementia compared with those who were not diagnosed with the heart condition. These increased risks were even higher in the absence of stroke, at 23% and 52%, respectively, according to the researchers.

Why Younger Patients Might Be More Vulnerable

The findings align with previous studies suggesting that atrial fibrillation contributes to cognitive decline through mechanisms independent of clinical stroke.

“Dementia is often a multifactorial condition,” García said. “This may explain why atrial fibrillation has a greater impact in younger patients, where it could be one of the primary pathogenic factors. Conversely, in older individuals, additional contributors to cognitive decline — such as age-related neurodegeneration — may lessen the relative impact of atrial fibrillation.”

While cognitive screening may be beneficial in younger patients with atrial fibrillation, Garcia said “an even greater priority should be the intensive management of atrial fibrillation risk factors — hypertension, diabetes, and sleep apnea — as well as atrial fibrillation itself through anticoagulation and rhythm control.”

A Role for Cardiologists? 

John Dodson, MD, MPH, director of the Geriatric Cardiology Program at NYU Langone Health, New York City, highlighted the study’s strengths, including its large sample size and long follow-up period. “Since dementia takes a long time to develop, this period allows enough cases to accrue so that they can look at independent risk factors for the outcome,” he told Medscape Medical News.

Dodson also said the findings raise important questions about treatment. “It’s unclear whether strategies that we use to treat atrial fibrillation as cardiologists could reduce the incidence of dementia,” he said. “It’s a plausible hypothesis that proper anticoagulation, and maybe even maintaining normal physiology with restoration of sinus rhythm, could lower patients’ risk. These are very difficult things to prove but I think a worthy avenue for more research.”

Alan Go, MD, associate director at the Kaiser Permanente Northern California Division of Research, said the findings echo US data showing stronger associations between atrial fibrillation and dementia in younger populations.

“Based on current evidence, for a person found to have atrial fibrillation without an obvious reversible cause, especially if under age 70 years, systematic evaluation for and treatment of cardiovascular risk factors should be performed,” Go said. People at risk for ischemic stroke should also engage in shared decision-making about oral anticoagulation, he said.

Go underscored the need for randomized, controlled trials that test whether preventing or effectively managing atrial fibrillation can delay or prevent dementia. “This observational study is limited as it didn’t address several potential explanatory factors,” said Go. “But it highlights the need for trials that look at whether preventing development or recurrence of atrial fibrillation has any impact on a person’s rate of cognitive decline and risk of ultimately developing dementia.”

This study was funded with a restricted grant by Bayer. The investigators disclosed no conflicts of interest. Dodson and Go reported no relevant conflicts of interest.