Atrial fibrillation (AF)—a heart rhythm disorder—diagnosed before age 70 is associated with a 21 % increase in the risk of developing dementia, and up to a 36 % increase for early-onset dementia (before age 65). The association is strongest in younger adults and weakens in those over 70. These findings come from a Bellvitge University Hospital–led study, in partnership with IDIAP Jordi Gol, presented at the EHRA 2025 meeting of the European Society of Cardiology in Vienna this week.
Population-Based Study
“This is the largest population-based European study to date assessing the link between AF and dementia,” explain Dr Julián Rodríguez García and Dr Andrea Di Marco, specialists in the Electrophysiology and Arrhythmias Unit at Bellvitge University Hospital’s Heart Disease Department. “The relationship is particularly pronounced in patients under 70, and very notable in cases of early-onset dementia,” they add.
Atrial fibrillation causes an irregular heartbeat and is relatively common, with an estimated prevalence of 2 %–3 % in the general population, increasing with age.
Previous studies had suggested a possible independent association between AF and dementia but yielded contradictory results. The strength of this relationship and its link to stroke remains debated. “Identifying the highest-risk subgroups can help us better understand the underlying mechanisms and guide more effective preventive strategies,” says Dr Ignasi Anguera, head of the Electrophysiology and Arrhythmias Unit and researcher with the Bio-Heart group at IDIBELL.
SIDIAP Data and Methodology
Catalan population data were analyzed by Dr Jordi Blanch from the Girona Research Support Unit at the Jordi Gol i Gurina Primary Care Research Institute (IDIAP Jordi Gol). They come from the Information System for the Development of Research in Primary Care (SIDIAP), which collects anonymized records for over 80 % of the population. This observational, population-based study began in 2007 with participants aged 45 or older and no prior dementia diagnosis.
Dementia was identified using International Classification of Diseases (ICD-10) codes and prescriptions for dementia-specific medications. Early-onset dementia was defined as diagnosis before age 65. Follow-up lasted 15 years, through 2021.
A total of 2,520,839 individuals were included, with an average follow-up of 13 years. At baseline, 79,820 patients (3.25 %) had an AF diagnosis. Multivariable analysis adjusted for confounders showed that AF is a statistically significant but overall modest predictor of dementia (4 % increased risk).
Age as a Key Factor
Age plays a critical role: the strength of the AF–dementia association decreases progressively with age. The association peaks in patients aged 45–50 and loses statistical significance after age 70.
Thus, in patients diagnosed with AF before age 70, the risk of dementia rises by 21 %, and for early-onset dementia by 36 %.
The researchers note that “dementia is a multifactorial condition with multiple neuropathological causes. This could explain why AF has a greater impact on younger patients, in whom it may act as one of the primary factors. In older ages, other causes like age-related neurodegeneration can dilute the effect of AF.”
Sensitivity analyses excluding patients with prior stroke reinforce the findings: AF remains associated with a 6 % increased risk of overall dementia, 23 % in middle-aged patients, and 52 % in early-onset cases. Therefore, the AF–dementia link may involve mechanisms beyond stroke, such as microinfarcts, microhemorrhages, or silent strokes detectable only by CT or MRI.
Additionally, “AF may cause hemodynamic changes and autonomic dysfunction affecting cerebral circulation. Systemic inflammation associated with AF could amplify these effects and create a synergistic pathway to dementia,” the authors suggest.
“Our study clearly demonstrates a significant association between two of the 21st century’s major health threats: atrial fibrillation and dementia. Further research is needed to determine whether early detection and more intensive AF management in younger patients can help prevent or delay dementia onset,” the authors conclude.
