Cardiovascular function, cortical thickness and cognitive performance in middle-aged Hispanic adults
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Background: Alzheimer's disease (AD) prevalence has grown 68% in that timeframe, and has risen to the sixth leading cause of death in the United States. Hispanics are at increased risk of acquiring cardiovascular risk factors that contribute to AD pathology and are minimally 1.5 times more likely at any age to be diagnosed with AD. Identifying the roots of this ethnic disparity can lead to more effective personalized health interventions. Aim: To compare indices of vascular health to measures of gray matter integrity in middle-aged Hispanic and Caucasian adults. As a secondary outcome, we will examine these health statuses in relation to cognitive function. Methods: Sixty subjects in Caucasian (n=30) and Hispanic (n=30) groups were matched across racial classification by age, gender, years of education, and cognitive status. Participants' arterial stiffness (carotid-femoral pulse-wave velocity and [beta]-stiffness index), arterial wave reflection (augmentation index), endothelial function (flow-mediated dilation), and atherosclerosis (carotid arterial wall intima-media thickness) were characterized. Magnetic resonance imaging (MRI) estimated cortical thickness in a priori cortical regions of interest known to be susceptible to vascular risk factors. Cognitive function was assessed with a comprehensive cognitive battery covering the domains of global cognitive function, language function, visuo-spatial abilities, memory function and attention-executive function. Results: Carotid-femoral pulse wave velocity (cfPWV) (p=0.02), Carotid artery [beta]-stiffness index (p=0.01), and augmentation index (Aix) (p=0.05) were significantly greater in Hispanics than in Caucasians. Carotid intima-media thickness (IMT) and flow-mediated dilation (FMD) were not different between the groups. Hispanics exhibited thinner left inferior frontal gyrus (LIFG) cortical thickness (p=0.04) with concurrently lower language (p=0.02), memory (p=0.03), and attention-executive functioning (p=0.02). Conclusion: Hispanics exhibited significantly greater cfPWV, Aix, and [beta]-stiffness index as well as selective cortical thinning of the LIFG. Additionally, language, working memory and attention-executive domains of cognition were lower in the Hispanic group compared to their age-, gender-, education- and cognitive status-matched Caucasian counterparts. These results may form a basis for future investigations that aim to explain the increased prevalence and earlier onset of symptoms of AD in the Hispanic population through cardiovascular health.