Decoding the Disparity: An Analysis of the Functional Connectivity Profile of Elderly African Americans with and without Alzheimer’s Disease

African Americans are twice as likely as non-Hispanic Whites to develop Alzheimer’s Disease. Current approaches to studying Alzheimer’s disease do not include a sufficient minority population needed to understand the nature of this disparity. Evidence from epidemiological and cerebrospinal fluid biomarker studies suggests that African Americans do indeed represent a unique phenotype of Alzheimer’s disease, partly driven by an elevated presence of risk factors. These risk factors include, but are not limited to an elevated presence of vascular disease which can manifest in the brain in the form of White Matter Hyperintensities (WMH). Functional magnetic resonance imaging is a method of detecting brain activity, and has been used to detect neurological changes within Alzheimer’s Disease in the form of functional connectivity (FC). FC is a measure of the correlation of activity between brain regions. In our first aim, we examined connectivity between a well-studied network, the default mode network and how race modifies the relationship between AD biomarkers and connectivity, and whether WMH in this network accounts for these racial differences. We found that race does modify the relationship between CSF t-Tau, Aβ42, and cognitive performance between the midline core and dorsomedial subsystems, but that WMH did not account for these differences. In our second aim, we analyzed connectivity between regions not typically associated with AD including the anterior putamen, pre and post central gyri, and superior and middle frontal gyri. We found that, independent of race, anterior putamen to pre and post central gyri increased as CSF Aβ42 decreased, but the connectivity decreased as regional WMH volume increased. Within African Americans, connectivity between the middle and superior frontal connectivity decreased as CSF Aβ42 decreased, and as regional WMH volume increased. This work further characterizes the AA dementia profile, and provides novel regions of exploration that may be affected by AD. Furthermore, we provide neurological support for the claim that in studies of individuals with Alzheimer’s disease, race should be considered as an important factor of interest in analyses