Our findings further confirmed that plasma NCAM single‐labeled exosomal Aβ42, Aβ42/40, T‐tau, and P‐T181‐tau have promising applications in the diagnosis of aMCI and AD as well as the differential diagnosis of VaD, serving as a substitute for CSF markers for inspection and PET inspection. The gene discussed is MAPT; the disease is Alzheimer disease.