# Plasma biomarkers, brain amyloid pathology, and cortical thickness in a racially diverse community cohort: the Human Connectome Project

## TL;DR

This study explores how plasma biomarkers relate to brain amyloid and cortical thickness in a diverse group of people.

## Contribution

The study evaluates racial differences in plasma biomarker correlations with brain pathology in a community cohort.

## Key findings

- Plasma p-tau217 accurately identifies abnormal Aβ-PET with high AUC.
- Biomarkers showed poor performance in identifying cortical thickness.
- Correlations between biomarkers and Aβ-PET were stronger in non-Hispanic Whites than in Black/African Americans.

## Abstract

Plasma biomarkers are critical for early detection and treatment of Alzheimer's disease (AD). We assessed plasma biomarker association and classification capacity against neuroimaging measures.

In the racially diverse Human Connectome Project (HCP; n = 218, 15% Aβ‐PET‐positive) Aβ‐PET and cortical thickness (neurodegeneration) were related to plasma biomarkers (p‐tau181, p‐tau217 [Janssen and ALZpath], p‐tau231, GFAP, NfL, Aβ42/Aβ40).

Plasma p‐tau217 accurately identified abnormal Aβ‐PET (: AUC=0.9145, 95% CI=[0.8367, 0.9923]) followed by GFAP and Aβ42/40 ratio (GFAP (AUC=0.8529, 95% CI = [0.7485, 0.9573], Aβ42/40 (AUC = 0.7962, 95% CI = [0.6581, 0.9346]). All biomarkers performed poorly to identify cortical thickness, but were increased according to combined Aβ‐PET‐neurodegeneration profiles. Correlations of p‐tau217, p‐tau181, and Aβ42/40 with Aβ‐PET were stronger in self‐identified non‐Hispanic Whites vs. Black/African Americans.

Plasma biomarkers identify brain Aβ pathology in the community. However, consideration of potential racial/ethnic differences in brain‐to‐blood biomarker correlations should be critically examined and addressed to enable widespread cross‐population applications.