Incidence and Prognostic Indicators of Dementia in Patients With Covert Brain Infarction, Transient Ischemic Attack, and Stroke: The Population-Based Rotterdam Study

BACKGROUND: Cognitive impairment is common after transient ischemic attack (TIA) and stroke, but contemporary population-representative estimates of dementia risk after stroke are scarce, particularly in view of stroke severity and competing risk of mortality. METHODS: We included individuals from the population-based Rotterdam Study with first-ever covert brain infarction (n=630), TIA (n=547), minor stroke (National Institutes of Health Stroke Scale score <4; n=392), or major stroke (National Institutes of Health Stroke Scale score ≥4; n=493) between 2002 and 2018, and matched those 1:3 to reference participants on age and sex. We determined 10-year dementia risks by event severity, comparing cause-specific and subdistribution hazards models to account for competing risk of death, and explored prognostic indicators of dementia after TIA and stroke. RESULTS: Of 1431 patients with first-ever TIA or stroke (mean age 75.2years, 58.3% women), 161 had pre-event dementia and 205 developed dementia during a median follow-up of 6.1years. After 10years, 59.4% of patients had died, with highest risk in the first months after major stroke. Compared with reference participants, dementia risk was increased after minor (cause-specific hazard ratio [HR], 1.60 [95% CI, 1.21–2.12]) and major stroke (HR, 1.72 [95% CI, 1.29–2.30]), but not TIA (HR, 0.97 [95% CI, 0.76–1.23]). Among those with covert brain infarction, dementia risk was between that of TIA and minor stroke (HR, 1.34 [95% CI, 0.98–1.83]). Accounting for mortality, 10-year dementia risk ranged from 14% (95% CI, 12%–19%) after TIA to 21% (95% CI, 16%–25%) after minor stroke and 16% (95% CI, 12%–20%) after major stroke. These risks were substantially higher in the Kaplan–Meier-estimations for minor stroke (33%) and major stroke (40%). Prognostic indicators for dementia after TIA and stroke included higher age, less education, premorbid cognition, APOE-ε4-carriership, hypercholesterolemia, and on neuroimaging hippocampal and white matter hyperintensities volume, cortical thickness, and ≥2 cerebral microbleeds. CONCLUSIONS: Dementia risk is elevated after stroke, and to a lesser extent covert brain infarction, but not after TIA. Excess risk extends to long-term follow-up for minor stroke, whereas competing risk of death attenuates risk after major stroke. Clinical and imaging indicators hold potential for personalized estimation of dementia risk.