Racial differences in white matter hyperintensity load in aging, MCI, and AD

Abstract

AbstractBackgroundCerebral small vessel disease (CSVD), often measured using white matter hyperintensities (WMHs) is a pathological change to the brain that increases ones’ risk for both age‐related cognitive decline and dementia. Several studies have noted that there is greater risk of CSVD in African Americans than in Caucasians. However, limited research has examined WMHs as a proxy of CSVD in an ethnically diverse sample. The goal of this research was to determine whether WMH load differs between African Americans and Caucasians.MethodsParticipants for this study were selected from the Alzheimer’s Disease Neuroimaging Initiative (ADNI1, GO, 2, and 3). They were included if they had baseline WMH measurements and a baseline diagnosis. WMHs were segmented using a previously validated automatic technique (Dadar et al., 2018). A total of 91 African Americans and 1846 Caucasians were included in this analysis. To compare samples, 91 Caucasian participants were randomly matched to African Americans based on age, sex, education, and diagnosis. This random selection was completed 1000 times using bootstrap resampling. A linear mixed effects was completed to examine the influence of race on WMH load: WMH ∼ Race + Age + Sex + Education + Diagnosis. The 95% confidence limits of the t‐statistics distributions for the 1000 samples were examined to determine whether the differences were statistically significant.ResultsThe following figure shows the t‐statistic, 95% confidence intervals, and p‐value distributions of the 1000 bootstrapped samples. The 95% confidence intervals are between t=‐3.06 and t=‐0.89 for total WMH load, indicating significance, as the limits do not include 0.ConclusionsAccounting for age, sex, education, and diagnostic status, racial differences were observed for total WMH load. That is, African Americans had higher total WMH load than Caucasians. Future research should examine whether these findings are observed longitudinally and if they influence cognition in an ethnically diverse sample.