Comparative risk of dementia between direct oral anticoagulants and warfarin after atrial fibrillation related ischemic stroke.

INTRODUCTION: Direct oral anticoagulants (DOAC) have been associated with a reduced risk of dementia compared to warfarin in patients with atrial fibrillation (AF) without prior stroke. However, the impact of DOAC on dementia risk in AF-related ischemic stroke survivors is unclear. METHODS: We conducted a retrospective, nationwide cohort study using the Korean National Health Insurance Service database. We identified patients with newly diagnosed ischemic stroke and concurrent AF who began DOAC or warfarin therapy within one month after stroke. Incidence of all-cause dementia, Alzheimer's dementia (AD), and vascular dementia (VaD) was compared between groups using multivariable Cox models with inverse probability of treatment weighting. RESULTS: A total of 3,112 patients (mean age 70.6 ± 9.5 years; 66.6% male) were analyzed, including 2,919 DOAC users and 193 warfarin users. Over a mean follow-up of 3.63 years, 673 all-cause dementia cases (538 AD, 168 VaD) occurred. After IPTW, DOAC use was associated with higher risks of all-cause dementia (HR 1.16, 95% CI 1.04-1.30) and AD (HR 1.85, 95% CI 1.62-2.13) but a lower risk of VaD (HR 0.54, 95% CI 0.45-0.66) compared to warfarin. DISCUSSION: In this retrospective nationwide cohort of AF-related ischemic stroke survivors, DOAC use was associated with a higher incidence of all-cause dementia and Alzheimer's dementia, but a lower incidence of vascular dementia, compared with warfarin. These observational findings suggest that anticoagulant type may be differentially associated with subsequent dementia subtypes in this high-risk population and should be interpreted with caution.