In this prospective study, we investigated plasma phosphorylated tau 217 (p‐tau217), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) in 341 unselected participants from a neuropsychiatry memory clinic, including AD (n = 40), behavioral variant FTD (bvFTD) (n = 15), PPD (n = 69), other NDs, and controls. The gene discussed is MAPT; the disease is Alzheimer disease.