WHITE MATTER VULNERABILITY AND CARDIOVASCULAR RISK IN OLDER HISPANICS/LATINOS: EVIDENCE FOR EARLIER NEURODEGENERATION?

Abstract

Hispanics 65 years and older are one of the fastest growing minority populations in the US and also one of the most medically underserved. For example, when compared to non-Hispanic whites, Hispanics have higher rates of uncontrolled cardiovascular disease risk factors (CVD-RFs) including hypertension and diabetes and twice the risk of dementia including Alzheimer's disease. Evidence suggests that cardiovascular disease risk factors may contribute to the earlier development of cognitive (i.e., executive functioning and information processing speed) and cerebral white matter alterations (i.e., white matter hyperintensities; WMH) in Hispanics. Overt white matter damage including WMHs may be driven, in part, by alterations in myelin integrity. We quantified myelin integrity using multicomponent relaxometry (MCR) in Hispanics and non-Hispanic Whites to explore for ethnic differences in associations to cardiovascular disease risk factors in these groups. We obtain the risk of stroked based on cardiovascular disease risk factors using the Framingham Stroke Risk Profile Score and acquired MCR data using a 3T GE MRI. 15 Hispanics (x̅age=62.7 years & FSRP=7.5; 66% women) and 15 non-Hispanic Whites (x̅age=69.7 years & FSRP=11.1; 40% women) with documented cardiovascular risk factor burden were compared to a group of 11 non-Hispanic whites (x̅age=71.0 years) without any cardiovascular risk factors. Figure 4 shows comparable differences in myelin degradation between Hispanics (yellow) and non-Hispanic whites (green) despite the fact that Hispanics were significantly younger (mean age=62.7 versus non-Hispanic whites mean age=69.7; p<0.001) with significantly lower cardiovascular disease scores as measured by the Framingham Stroke Risk Profile (FSRP) Score (FSRP=7.5 versus non-Hispanic whites’ mean=11.1; p<0.01). This preliminary study suggests that myelin degradation, associated with even mild vascular disease burden, is detectable using MCR. Furthermore, despite being significantly younger with less stroke risk associated with cardiovascular disease risk factors, Hispanics displayed comparable myelin degradation to older non-Hispanic whites with greater cardiovascular risk. Myelin integrity associated with cardiovascular disease risk burden was greater for Hispanics (yellow) than non-Hispanic whites (green) when compared to healthier controls.