MAPT and Alzheimer disease: In addition, no significant differences were observed in T‐tau, P‐T181‐tau, and NfL levels as well as their efficiencies for AD diagnosis and staging between NCAM single‐labeled and NCAM/ABCA1 double‐labeled exosomes, suggesting that there is no need to detect NCAM/ABCA1 dual‐labeled exosomal T‐tau, P‐T181‐tau, and NfL for diagnosis and staging of AD.