Diversity considerations of white matter hyperintensities and connectivity in normal aging and MCI

Abstract

AbstractBackgroundAlzheimer’s disease (AD) is twice as likely to occur in African Americans than in Non‐Hispanic Whites. However, current neuroimaging models of AD do not accurately overlay onto the African American profile of this disease. One variable that could contribute to more accurate modeling is the inclusion of vascular factors into models of AD, as African Americans are more likely to have vascular as well as AD. Functional MRI is a widely used method to measure brain activity in individuals with AD. Connectivity in the form of correlated between regions can be used to determine neurological dysfunction. Fronto‐striatal connectivity, while understudied in AD, has shown to be affected by AD and vascular disease. This study attempts to determine if there are connectivity measures that relate to vascular lesions(White Matter Hyperintensities (WMH)) across the disease spectrum, and whether these relationships are uniform across race.MethodWe analyzed data from 88 people (54= NC, 34=MCI). We conducted functional connectivity using DPARSFA toolbox with connectivity calculated between the following fronto‐striatal regions within each hemisphere: anterior putamen, middle frontal gyrus, superior frontal gyrus (putamen output regions), pre‐ and postcentral gyri (putamen input regions). To calculate regional white matter hyperintensity we used in‐house code to overlay a regional atlas onto a WMH mask extracted from a T2 weighted FLAIR image, and assigned a score to each individual representing load (0=no WMH in any regions, 1=WMH in 1 or the other region, 2=present in both regions.ResultAcross race and diagnostic categories, WMH were related negatively to right anterior putamen connectivity to the pre and post central gyri such that as WMH load increased, connectivity also decreased. This relationship continued for connectivity measures between the right anterior putamen and the superior and middle frontal gyri, but only within African Americans.ConclusionFronto‐striatal connectivity did correlate with regional WMH load in a uniform manner across races for cortical input regions to the putamen, and this relationship extended to Africans Americans within cortical output regions. This relationship was identified across diagnostic categories, and could be useful in studies investigating vascular relationships to AD biomarkers.