A large population-based study in Europe has found that atrial fibrillation (AFib)—a common heart rhythm disorder—is linked to a significantly higher risk of dementia, especially in adults diagnosed with AFib before the age of 70.
The findings, presented at EHRA 2025 (a scientific meeting of the European Society of Cardiology), reveal that AFib increases the risk of future dementia by 21% in people under 70, and the risk of early-onset dementia (before age 65) by 36%.
AFib affects 2–3% of the general population and becomes more common with age. It causes an irregular, often rapid heartbeat and is a well-known risk factor for stroke. But its link to dementia has been debated for years.
In this new study—the largest of its kind in Europe—researchers from Bellvitge University Hospital in Barcelona, Spain, aimed to better understand the connection between AFib and dementia over time and across different age groups. They followed over 2.5 million adults in Catalonia, Spain, for an average of 13 years, analyzing medical data from 2007 to 2021.
Key Findings:
- At the beginning of the study, 79,820 individuals (3.25%) had AFib but no dementia.
- During follow-up, dementia was diagnosed using medical codes and prescriptions for dementia-related medications.
- In the full study population, AFib was linked to only a small (4%) increase in dementia risk.
- However, age made a huge difference:
- In people under 70, AFib increased the risk of dementia by 21%.
- For early-onset dementia (diagnosed before age 65), AFib raised the risk by 36%.
- In people aged 70 and older, the association disappeared—there was no significant link between AFib and dementia.
When researchers excluded participants who had experienced a stroke (a known risk factor for dementia), the pattern remained the same:
- 6% increase in overall dementia risk from AFib.
- 23% increase in risk for those under 70.
- 52% increase in the risk of early-onset dementia.
Why Does AFib Raise Dementia Risk?
The exact reasons aren’t fully understood, but the authors suggest several possible mechanisms:
- Silent strokes: Small strokes with no obvious symptoms that can go unnoticed but still damage the brain.
- Microinfarcts and microbleeds: Tiny brain injuries caused by poor blood flow or bleeding.
- Blood flow problems: AFib can affect how blood flows to the brain, potentially damaging small vessels over time.
- Autonomic nervous system changes: AFib can affect how the body regulates automatic functions like blood pressure and heart rate.
- Inflammation: AFib is linked with higher levels of inflammation in the body, which may play a role in brain damage.
Interestingly, the researchers found that dementia risk was highest in younger adults with AFib, suggesting that AFib may act as a more dominant factor in younger brains, while in older adults, age-related brain changes and other diseases may play a larger role.
What This Means
This study provides strong evidence that AFib is more than just a heart rhythm issue—it may also be a risk factor for cognitive decline, especially when diagnosed earlier in life. While many previous studies were small or showed mixed results, this research adds clarity by analyzing a large, real-world population over a long period of time.
Public Health Implications
- Younger adults diagnosed with AFib may need closer monitoring for cognitive decline.
- Health care providers may consider early intervention strategies for AFib not just to prevent stroke, but also to protect brain health.
- More research is needed to see if aggressive treatment of AFib (such as medications, ablation, or lifestyle changes) could lower the risk of dementia.
Final Thoughts
As AFib and dementia are two of the major health challenges of the 21st century, this study offers valuable insight into how they may be connected—especially in younger adults. The researchers say the next step is to explore whether preventing or managing AFib early could help delay or reduce dementia, giving patients not only longer lives but healthier brains.
If you care about dementia, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and flavonoid-rich foods could help prevent dementia.
For more information about brain health, please see recent studies that cranberries could help boost memory, and how alcohol, coffee and tea intake influence cognitive decline.
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