Abstract 7: Association Between Incidence, Severity and Recurrence of Ischemic Stroke and Risk of Dementia: The Atherosclerosis Risk in Communities Study

Abstract

Background: Ischemic Stroke (IS) is associated with an increased risk of dementia, but the relative contribution of IS severity or recurrence to cognition is not known. We aimed to determine the risk of dementia after incident IS and how it varies by stroke severity and recurrence in the Atherosclerosis Risk in Communities (ARIC) study. Methods: 15,405 ARIC participants free of stroke and dementia at baseline (1987-9) were followed for IS and dementia through 2019. Incident and recurrent IS were classified by expert review of hospital records, with stroke severity by the National Institutes of Health Stroke Scale (NIHSS) classified as NIHSS≤5, 6-10, 11-15, ≥16. Dementia cases were adjudicated through expert review of in-person evaluations, informant interviews, phone assessments, hospitalization code or death certificates. Poisson regression models with robust error variance were used to estimate dementia incidence in participants with and without IS, and associations between time-dependent IS incidence (excluding dementia in the first year after stroke), frequency and severity, and dementia were studied with Cox proportional hazards models, adjusting for demographics, APOE ε4 and vascular risk factors . Results: 1151 IS (970 incident) and 2807 dementia cases were identified. NIHSS was available for 877 IS (76%). Adjusted incidence rates (95% CI) of dementia per 100 person-years were 0.45 (0.42-0.49) in participants without IS vs. 1.33 (1.15-1.55) in those with IS. Compared to no IS, risk of dementia (adjusted HR, 95% CI) increased with IS number and severity from 1.71 (1.47-1.99) for participants with one IS to 6.68 (3.58-12.46) for those with ≥3 events, and from 1.64 (1.36-1.98) for NIHSS≤5 to 4.43 (1.84-10.68) for NIHSS≥16 ( Table ). Conclusion: Risk of dementia is significantly increased after stroke, independent of vascular risk factors. These data suggest a dose-response relationship between number of stroke events and stroke severity, and risk of dementia.