New research presented at the European Heart Rhythm Association (EHRA) 2025 Congress reveals that atrial fibrillation (AF) significantly raises the risk of developing dementia, particularly in individuals diagnosed with the condition before age 70. The study, which is the largest European population-based investigation on this topic, found that AF increases the risk of dementia by 21% in patients under 70 and by 36% for early-onset dementia, diagnosed before age 65.
The study, led by Dr. Julián Rodriguez García of the Electrophysiology and Arrhythmia department at Bellvitge University Hospital in Barcelona, Spain, highlights a stronger connection between AF and dementia in younger patients. However, this association diminishes in those aged 70 and above.
AF, a condition characterized by an irregular heartbeat, affects approximately 2-3% of the general population, with its prevalence rising with age. Previous studies have suggested an independent link between AF and dementia, though the exact mechanisms and the role of stroke in this connection remain debated.
The study, which followed over 2.5 million individuals in Catalonia, Spain, examined the impact of AF on dementia risk over a 15-year period. Participants, aged 45 and older in 2007, had no prior dementia diagnosis at the study’s start. Dementia cases were identified using International Classification of Disease (ICD-10) codes and medication prescriptions, while early-onset dementia was defined as a diagnosis before age 65.
The findings showed that 3.25% of the study population had AF at baseline. While AF overall increased dementia risk by 4%, age proved to be a critical factor in the strength of this association. For those aged 45-50, AF patients were 3.3 times more likely to develop dementia than their counterparts without AF. However, no such association was found in individuals over 70 years old.
Further analysis revealed that for patients diagnosed with AF before 70, the risk of developing dementia increased by 21%, with an even greater impact on early-onset dementia (36%). The association, however, became statistically insignificant in those over 70 years old.
The researchers suggest that the multifactorial nature of dementia could explain these findings. In younger patients, AF might be a primary contributor to cognitive decline, while in older individuals, other factors like age-related neurodegeneration may reduce AF’s impact on dementia risk.
Sensitivity analyses that excluded patients with previous strokes still showed a significant association between AF and dementia. This suggests that factors beyond stroke—such as silent strokes, microinfarcts, and microbleeds—could contribute to the increased dementia risk in AF patients.
The researchers also pointed to potential mechanisms that might explain the AF-dementia link, including changes in blood flow and pressure caused by AF, autonomic dysregulation, and systemic inflammation. These factors could potentially damage small blood vessels in the brain, exacerbating dementia risk.
Concluding their findings, the authors stressed the importance of early detection and aggressive management of AF, particularly in younger patients, as a potential strategy for reducing dementia risk and altering the course of the disease. The study sheds light on the growing intersection between cardiovascular and neurodegenerative diseases, highlighting the need for targeted preventive interventions.
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