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Study finds ‘clear correlation’ between AF and risk of vascular dementia

Study finds ‘clear correlation’ between AF and risk of vascular dementia

A new study has demonstrated a ‘clear correlation’ between atrial fibrillation (AF) and vascular dementia, a type of dementia caused by problems in the blood vessels that supply the brain.

Researchers at the University of Birmingham found that individuals with AF, who were considered ‘low-risk’ patients, had a 68% higher chance of developing vascular dementia than patients without the heart condition. There was however no correlation with the development of Alzheimer’s disease.

The researchers also found that the low-risk patients had double the chance of developing a stroke or major blood clot than those without AF and suggest that a thromboembolic mechanism is contributing to the development of vascular dementia in patients with AF.

The findings, published in Nature Medicine, highlight an additional consequence of AF, which the researchers advise clinicians to be aware of and attempt to prevent, particularly amongst younger, lower risk AF patients.

Atrial fibrillation is one of the most common heart conditions, with over 60 million cases expected worldwide by 2050. It is known to be associated with strokes and blood clots in older patients and those with other health conditions.

Patients with AF are typically given anticoagulants as stroke prevention therapy but younger patients and those otherwise perceived as ‘low-risk’ are not prescribed the blood thinning medication.

The study was a UK population-based analysis using electronic healthcare records from 5,199,994 primary care patients collected between 2005 and 2020. Just over 5% (290,525) of the patients analysed, who were all between the ages of 40 and 75, had a diagnosis of AF.

The researchers focused on 36,340 AF patients who were not receiving anticoagulation therapy and were considered low risk based on a standard risk score (CHA2DS2-VASc score <2). The team compared these patients’ outcomes with those of 117,298 control patients without AF, who were matched for age, sex, and region.

Rates of death and thromboembolic outcomes, including vascular dementia, during the study were substantially increased in the patients with AF despite their low-risk status.

In the five-year follow up period, 3.8% of patients with AF had a stroke compared with 1.5% of those without AF. Meanwhile 5.6% versus 2.7% developed ischaemic heart disease, respectively. All-cause mortality was also increased in those with AF, at 8.9% versus 5% for those without.

Adjusting for various potential contributing factors, the authors found AF was associated with a two-fold increased risk of stroke and 1.9-fold increased risk of ischaemic heart disease.

AF was also associated with an increased rate of all-cause dementia (1.2% versus 0.7% in those without AF). The report this was driven by vascular dementia cases (0.4% versus 0.1%, respectively), and that those with AF had a 1.68-fold increased risk of developing vascular dementia compared to those without AF after adjusting for other factors.

Alastair Mobley, a PhD researcher at the University of Birmingham and first author of the study, said: ‘This study demonstrates a clear correlation between AF and vascular dementia. This may have a similar mechanism to the association between AF and stroke.’

The prevention of thromboembolism in AF is typically restricted to older patients or those with specific risk factors and currently does not consider outcomes such as vascular dementia. Ongoing clinical trials such as DaRe2THINK are exploring whether anticoagulants in lower-risk patients can provide a way to prevent the increased risk of thromboembolic outcomes, including vascular dementia.

Dipak Kotecha, Professor of Cardiology at the University of Birmingham and senior author of the study, added: ‘Atrial fibrillation is one of the most common heart conditions. With its prevalence continuing to rise, it is crucial that we develop strategies to prevent not only stroke but outcomes like dementia, which are a big concern for patients and healthcare systems. Our research highlights the urgency of addressing AF comprehensively, considering its overall impact on the well-being of patients.’

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