The influence of vascular risk factors and stroke on cognition in late life analysis of the NACC cohort

Objective: Vascular risk factors in mid-life predict late life cognitive decline in previously normal populations. We sought to investigate the contribution of vascular risk factors in late life to cognitive decline in a cohort of normal elderly individuals. Methods: Cognitively normal subjects were identified from the longitudinal cohort of participants in the National Alzheimer Coordinating Center (NACC) database (n=2975). The association between a composite score of vascular risk factors (based on the Framingham Stroke Risk Profile) and cognitive function was tested at baseline visit and estimated in longitudinal analyses using linear mixed-effects models. Results: Total vascular risk factor burden was associated with worse cognitive performance at baseline and faster decline longitudinally in univariate analyses but only with worse WAIS digit symbol performance in cross-sectional (estimate=-0.266 units/1 unit of Framingham Stroke Risk Profile Score; 95% confidence interval,-0.380 to-0.153; P<0.001) and longitudinal (estimate=-0.034 units/1 unit of Framingham Stroke Risk Profile Score/year; 95% confidence interval,-0.055 to-0.012; P=0.002) analyses after adjusting for age, education, and APOE genotype. Individuals with history of stroke performed significantly worse on the trails B, category fluency, and Boston naming tests in cross-sectional analyses and in delayed logical memory and digit span backwards in longitudinal analyses. Conclusions: Although the modified Framingham Stroke Risk Profile in late-life predicts rate of decline on selective neurocognitive measures in previously normal elderly individuals, age appears to be the strongest risk factor for cognitive impairment in this population. History of stroke independently influences rate of cognitive decline in these individuals.