AUTHOR=Hall James R. , Petersen Melissa , Johnson Leigh , O'Bryant Sid E. 

TITLE=Characterizing Plasma Biomarkers of Alzheimer's in a Diverse Community-Based Cohort: A Cross-Sectional Study of the HAB-HD Cohort

JOURNAL=Frontiers in Neurology

VOLUME=Volume 13 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2022.871947

DOI=10.3389/fneur.2022.871947

ISSN=1664-2295

ABSTRACT=Background: Due to their low cost, less invasive nature and ready availability, plasma biomarkers of Alzheimer’s disease have been proposed as one time screening tools for clinical trials and research. The impact of ethnoracial factors on these biomarkers has received little attention. The current cross-sectional study investigated the levels of Aβ40, Aβ42, total tau and NfL across diagnoses for each of the three major ethnoracial groups in the US in a community based cohort of older adults.  
Methods: 1862 participants (852 Mexican Americans (MA); 775 Non-Hispanic Whites (NHW) and 235 African Americans (AA)) drawn from The Health & Aging Brain Study – Health Disparities (HABS-HD) study were included. Diagnoses were assigned using an algorithm (decision tree) verified by consensus review. Plasma samples were assayed using Simoa technology. Levels of each biomarker were compared for the three ethnoracial groups across cognitive diagnoses using ANOVA co-varying sex and age.   
Results: Significant differences were found across the groups at each level of cognitive impairment. Cognitively unimpaired AA had significantly lower levels of each of the biomarkers and NHW had higher levels of Aβ40, Aβ42 and NFL. MA had the highest level of t tau. MCI group NHW had the highest levels on all the biomarkers and AA had the lowest. NHW and MA has higher levels of Aβ40, Aβ42, total tau there was no difference between the groups for Aβ42. NHW had significantly higher levels of Aβ40, t tau and NfL than AA. 
Conclusions: The use of plasma biomarkers of cognitive decline is promising given their advantages over other biomarkers such as CSF and imaging but as the current research shows, ethnoracial differences must be considered to enhance accuracy and utility. Developing ethnoracial specific cut points and establishing normative ranges by assay platform for each of the biomarkers are needed. Longitudinal research to assess changes in biomarkers during cognitive decline is ongoing.