MAPT and Alzheimer disease: The AUC for serum p75NTR-ECD in AD versus EC was 0.752 (95% confidence interval=0.695–0.808), which was higher than any of the AUC values generated by each of the known serum biomarkers (Aβ42, Aβ40, total Aβ, Aβ42/Aβ40, ptau181, total tau, ptau181/Aβ42 and total tau/Aβ42; Supplementary Table 2).