Atrial Fibrillation Is an Independent Determinant of Low Cognitive Function

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Abstract
Cerebrovascular disease is increasingly recognized as a cause of dementia and cognitive decline. We have previously reported an association between hypertension and diabetes and low cognitive function in the elderly. Atrial fibrillation is another main risk factor for cerebrovascular disease. The aim of this study was to investigate whether atrial fibrillation is associated with low cognitive function in elderly men with and without previous manifest stroke. This was a cross-sectional study based on a cohort of 952 community-living men, aged 69 to 75 years, in Uppsala, Sweden. Cognitive functions were assessed by the Mini-Mental State Examination and the Trail Making Tests, and a composite z score was calculated. The relation between atrial fibrillation and cognitive z score was analyzed, with stroke and other vascular risk factors taken into account. All analyses were adjusted for age, education, and occupational level. Men with atrial fibrillation (n=44) had lower mean adjusted cognitive z scores (-0.26+/-0.11) than men without atrial fibrillation (+0.14+/-0.03; P=0.0003). The exclusion of stroke patients did not alter this relationship; the mean cognitive z score was -0.24+/-0.12 in the 36 men with atrial fibrillation and +0.17+/-0.03 in those without atrial fibrillation (P=0.0004), corresponding to a difference of 0.4 SDs between groups. Adjustments for 24-hour diastolic blood pressure and heart rate, diabetes, and ejection fraction did not change this relationship. Men with atrial fibrillation who were treated with digoxin (n=27) performed markedly better (-0.05+/-0.21) than those without treatment (n=9; -1.14+/-0.34; adjusted P=0.0005). Previous myocardial infarction was not associated with impaired cognitive results. In these community-living elderly men, we found an association between atrial fibrillation and low cognitive function independent of stroke, high blood pressure, and diabetes. Interventional studies are needed to answer the question of whether optimal treatment of atrial fibrillation may prevent or postpone cognitive decline and dementia.