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 75.2 years, 58.3% women), 161 had pre‐event dementia and 205 developed dementia during a median follow‐up of 6.1 years. After 10 years, 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.