Background: Atrial fibrillation (AF) is associated with higher risk of dementia and Alzheimer's disease. To better understand the mechanism, we examined neuropathologic changes seen with AF.
Methods: We analyzed data from an autopsy series arising from a population-based, prospective cohort study set within Group Health, an integrated health care delivery system. Participants were people aged 65 and older, community-dwelling, and nondemented at study enrollment, who died during follow-up and underwent autopsy. AF was defined from medical records. Permanent AF was defined as having two or more electrocardiograms showing AF between 6 and 36 months apart with no evidence of sinus rhythm in between. The primary study outcomes were gross infarcts, neuritic plaques, and neurofibrillary tangles, ascertained using consensus guidelines. Adjusted relative risks and 95% CIs were calculated using modified Poisson regression, weighted to account for selection into the autopsy cohort.
Results: Three hundred and twenty-eight participants underwent autopsy; 134 (41%) had AF. People with AF were more likely to have gross infarcts than those without AF (45% vs 31%; relative risk 1.82, 95% CI 1.23-2.71); in 30%, these infarcts were not clinically recognized before death. Alzheimer's disease neuropathologic changes were not associated with ever having AF but were more common in people with permanent AF. Adjusted relative risks for frequent neuritic plaques and neurofibrillary tangles were 1.47 (0.96-2.28) and 1.40 (0.79-2.49), respectively, for people with permanent AF versus no AF.
Conclusions: AF is associated with gross infarcts. Permanent AF may contribute to Alzheimer's disease neuropathologic changes, but more study is needed.
Keywords: Alzheimer's; Brain aging; Cardiac arrhythmias; Cardiovascular.; Stroke.