GFAP and Alzheimer disease: ,8,20, 21, 22, 23 Despite the good accuracy in identifying individuals on the AD pathway, there is variability in findings regarding the specific neuropathological changes these biomarkers reflect.24, 25, 26 In the context of neurodegenerative diseases, blood GFAP levels has been reported to rise in response to both amyloid20 or tau pathology.26