Effect of Cognitive Reserve on Risk of Cognitive Impairment and Recovery After Stroke: The KOSCO Study.

ABSTRACT

Background and Purpose- The theory of cognitive reserve (CR) was introduced to account for individual differences in the clinical manifestation of neuropathology. This study investigated whether CR has a modulating effect on cognitive impairment and recovery after stroke. Methods- This study is an interim analysis of the Korean Stroke Cohort for Functioning and Rehabilitation. A total of 7459 patients with first-ever stroke were included for analysis. Education, occupation, and composite CR scores derived from those 2 variables were used as CR proxies. Scores from the Korean version of the Mini-Mental State Examination analyzed for 30 months after stroke onset were analyzed. Results- Lower CR increased the risk of cognitive impairment after stroke. The odds ratio was 1.89 (95% CI, 1.64-2.19) in patients with secondary education and 2.42 (95% CI, 2.03-2.90) in patients with primary education compared with patients with higher education. The odds ratio was 1.48 (95% CI, 1.23-1.98) in patients with a skilled manual occupation and 2.01 (95% CI, 1.42-2.83) in patients with a nonskilled manual occupation compared with patients with a managerial or professional occupation. In the multilevel model analysis, the Korean version of the Mini-Mental State Examination total score increased during the first 3 months (1.93 points per month) and then plateaued (0.02 point per month). The slopes were moderated by the level of education, occupation, and composite CR score the higher the level of education, occupation, or CR score, the faster the recovery. In the older adult group, the Korean version of the Mini-Mental State Examination scores showed a long-term decline that was moderated by education level. Conclusions- Education and occupation can buffer an individual against cognitive impairment caused by stroke and promote rapid cognitive recovery early after stroke. In addition, higher education minimizes long-term cognitive decline after stroke, especially in older patients. Clinical Trial Registration- URL https//www.clinicaltrials.gov. Unique identifier NCT03402451.