Cognitive reserve and risk of poststroke cognitive impairment in acute ischaemic stroke: post hoc analysis of CATIS-2

Background The impact of cognitive reserve (CR) on poststroke cognitive impairment (PSCI) remains unclear. This study aimed to investigate the association between CR proxy scores derived from an education-residence proxy index and PSCI. Methods We conducted a post hoc analysis of the China Acute Ischemic Stroke Hypotension Trial II cohort including acute ischaemic stroke (AIS) patients without prior dementia who completed 3-month cognitive assessment. A CR proxy score was constructed using principal component analysis based on education and residential location. PSCI was defined as Montreal Cognitive Assessment <25. Logistic regression and restricted cubic spline (RCS) analyses were used to examine associations between CR and PSCI. Results PSCI occurred in 1019 of 1682 patients (60.6%). Higher CR proxy scores were associated with lower odds of PSCI (OR=0.88; 95% CI 0.81 to 0.96; p=0.01), with similar findings in the fully adjusted model (OR=0.89; 95% CI 0.81 to 0.98; p=0.02). RCS analyses showed a linear inverse association between CR proxy scores and PSCI (P overall=0.001; P non-linear=0.35). Component analyses suggested that educational attainment was the predominant contributor to the observed association. Conclusions The education-residence-based CR proxy score was associated with lower odds of PSCI after AIS. The observed associations require cautious interpretation and further validation using comprehensive CR measures. Trial registration number NCT03479554 .