Plasma biomarkers, brain amyloid‐beta pathology, and cortical thickness in a non‐Hispanic White and Black/African American middle‐aged community cohort: The HCP‐CoBRA study

Plasma phosphorylated tau-217 (p-tau217) and glial fibrillary acidic protein (GFAP) best predicted abnormal brain amyloid beta-positron emission tomography (Aβ-PET). Plasma p-tau217 accurately identified abnormal Aβ-PET (Johnson & Johnson p-tau217: area under the curve [AUC] = 0.9145, 95% confidence interval [CI] = 0.8367-0.9923; ALZpath p-tau217: AUC = 0.9198, 95% CI = 0.8585-0.981) 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 plasma biomarkers performed poorly in identifying cortical thickness, despite being higher according to combined Aβ-PET and neurodegeneration profiles. Correlations of p-tau217 (Johnson & Johnson p < 0.001), p-tau181 (p = 0.005), and Aβ42/40 (p = 0.004) with Aβ-PET in predicting amyloid burden were stronger in self-identified non-Hispanic Whites vs Black/African Americans. Biomarker accuracies for Aβ-PET positivity were unaffected by self-identified race, except ALZpath p-tau217 (p = 0.024).