GFAP and Alzheimer disease: The mean levels of most plasma-based AD biomarkers were higher in AD than in controls, including P-tau181 (3.02 pg/mL (SD = 1.7) in AD and 2.13 pg/mL (SD = 1) in healthy controls), NfL pg/mL (26.4 (SD = 20.5) in AD and 17.3 pg/mL (SD = 19.2) in healthy controls), and GFAP pg/mL (219 (163) in AD and 140 pg/mL (96) in healthy controls).