GFAP and early-onset autosomal dominant Alzheimer disease: Plasma GFAP has shown superior diagnostic accuracy compared with GFAP measured in CSF, effectively distinguishing Aβ-positive from Aβ-negative individuals, predicting disease in at-risk populations and differentiating Alzheimer’s disease from other neurodegenerative disorders such as frontotemporal dementia.19-22 Therefore, blood and CSF GFAP were added to the existing [AT(N)] framework as biomarkers for reactive astroglial response.