Dementia After Stroke

TLDR

Risk factors for dementia after stroke are best identified by comparing stroke patients to stroke‑free controls, because older high‑stroke‑risk individuals also carry a substantial dementia risk, and prior studies were hospital‑based. The study prospectively evaluated dementia risk factors after stroke using a nested case‑control design within the community‑based Framingham cohort. Researchers compared 212 first‑stroke patients with 1,060 age‑ and sex‑matched stroke‑free controls, calculating 10‑year dementia risks and hazard ratios for demographic, stroke‑related, and risk‑factor exposures. Stroke patients had a 19.3% dementia incidence versus 11.0% in controls, with a doubled risk (HR ≈ 2.0) that remained elevated after adjustment (HR ≈ 2.4), especially in younger individuals, APOE 3/3 homozygotes, and high school graduates, indicating that stroke markedly increases dementia risk and that prevention could reduce it.

Abstract

Background and Purpose— Identification of risk factors for dementia after stroke is best performed in comparison with stroke-free controls, because older subjects at high risk for stroke also have a substantial risk of dementia in the absence of stroke. Previous case-control studies were hospital-based. We used a nested case-control design to prospectively evaluate these risk factors in the community-based Framingham Study cohort. Methods— We compared 212 subjects who were free of dementia in January 1982 and sustained a first stroke after this date, with 1060 age- and sex-matched, stroke- and dementia-free controls. We calculated 10-year risks of dementia (by Diagnostic and Statistical Manual of Mental Disorders , Volume IV criteria) developing in cases and controls and also estimated the hazard ratios within subgroups defined by exposure to various demographic factors (age, gender, education), stroke-related features (right or left hemisphere, stroke type, second stroke), stroke risk factors (hypertension, diabetes, atrial fibrillation, smoking) and apolipoprotein E genotype. Results— Dementia developed in 19.3% of cases and 11.0% of controls. Baseline stroke doubled the risk of dementia (hazard ratio [HR]: 2.0; 95% confidence interval [CI]: 1.5 to 3.1) and adjustment for age, sex, education, and exposure to individual stroke risk factors did not diminish the risk (HR: 2.4; 95% CI: 1.6 to 3.7). The HR was higher in younger subjects (age younger than 80 years [HR: 2.6; 95% CI: 1.5 to 4.5]), apolipoprotein E 3/3 homozygotes (HR: 3.4; 95% CI: 2.0 to 5.8), and high school graduates (HR: 2.4; 95% CI: 1.5 to 3.9). Conclusion— Stroke increases a subject’s risk of dementia as compared with age- and sex-matched controls. Primary and secondary prevention of stroke should significantly decrease the risk of all dementia.