Atrial fibrillation and risk of dementia: a prospective cohort study

OBJECTIVES: To determine whether atrial fibrillation (AF) is associated with risk of incident dementia or Alzheimer's disease (AD), beyond its effect on stroke. DESIGN: Prospective cohort study. SETTING: An integrated healthcare delivery system. PARTICIPANTS: A population‐based sample of 3,045 community‐dwelling adults aged 65 and older without dementia or clinical stroke followed from 1994 to 2008. MEASUREMENTS: AF was identified from health plan electronic data using International Classification of Diseases, Ninth Revision, codes from inpatient and outpatient encounters. Covariates came from self‐report, study measures, and health plan data. Participants were screened every 2 years using the Cognitive Abilities Screening Instrument (range 0–100), with detailed neuropsychological and clinical assessment of those scoring less than 86. A multidisciplinary consensus committee determined diagnoses of all‐cause dementia and possible or probable AD using standard research criteria. RESULTS: AF was present in 132 (4.3%) participants at baseline and was diagnosed in 370 (12.2%) more over a mean of 6.8 years of follow‐up; 572 participants (18.8%) developed dementia (449 with AD). The adjusted hazard ratio associated with AF was 1.38 (95% confidence interval (CI)=1.10–1.73) for all‐cause dementia and 1.50 (95% CI=1.16–1.94) for possible or probable AD. Results were similar for participants with and without clinically recognized stroke during follow‐up and in sensitivity analyses examining only probable AD. CONCLUSION: AF is associated with higher risk of developing AD and dementia. Future studies should examine whether specific treatments, including optimal anticoagulation, can decrease this risk.