COGNITIVE RESERVE AND RISK OF MOBILITY DISABILITY IN OLDER ADULTS

Abstract

Abstract Background Cognitive Reserve (CR) protects against cognitive decline and dementia but its relation to mobility disability has not been established. To address this important gap in the literature, we conducted a longitudinal investigation to test the hypothesis that higher baseline CR was associated with a lower risk of developing mobility disability in older adults. Methods Participants were dementia-free older adults who received a brain magnetic resonance imaging and had gait speed assessments during follow-up. Using the residuals approach, CR was derived from the modified-Mini-Mental Status Examination (3MS) total score by removing variance accounted for by measures of structural brain integrity, education and race. Mobility disability was defined using a validated cutoff score in gait speed of 0.8 m/s. Logistic regression models using General Estimating Equations (GEE) were utilized to examine longitudinal associations between baseline CR and the risk of developing of mobility disability across repeated assessments. Results Of the participants (n=237; mean age=82ys; %female=56%) who were free of mobility disability at baseline, 103 developed mobility disability during follow-up (mean=3.1ys). Higher CR at baseline was associated with lower risk of developing incident mobility/disability [odds ratio (OR)=.819, 0.67 to 0.98, p=.038 (unadjusted); OR=.815, 0.67 to 0.99, p=.04 (adjusted for socio-demographic variables and depression); OR=.819, 0.68 to 0.88, p=.035 (adjusted for illness history); OR=.824, 0.68 to 0.99, p=.045 (adjusted for white matter hyperintensities); OR= .795, 0.65 to 0.95, p=.016 (adjusted falls history)]. Conclusion We provided first evidence that higher CR was associated with lower risk of developing mobilitydisability in older adults.