GFAP and Alzheimer disease: The Alzheimer's Association provides three broad categories of AD‐related fluid biomarkers: (1) core biomarkers, including Aβ42, pTau217, pTau181, pTau23, and MTBR‐tau243; (2) non‐specific biomarkers involved in AD pathophysiology, including neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP); and (3) biomarkers of non‐AD co‐pathology alpha synuclein and neuroimaging evidence of infarction.3