GFAP and Alzheimer disease: In the current study, we aimed to investigate the utility of the combination of plasma biomarkers Abeta(1-42/1-40), GFAP, and NfL, all measured on a single platform (Simoa), to identify AD pathology as determined with amyloid PET in a total of 252 individuals across the clinical AD spectrum, i.e., subjective cognitive decline (SCD), mild cognitive impairment (MCI), or AD-dementia.