GFAP and Alzheimer disease: Phosphorylated-tau181 (pTau181), amyloid-β42/amyloid-β40 (Aβ42/Aβ40), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) have emerged as key biomarkers of Alzheimer’s disease and related dementias (ADRD).