MAPT and Alzheimer disease: If validated, these plasma biomarkers bring the potential to reflect the core events of CNS Alzheimer's disease pathology, such as amyloid pathology or glial activation (plasma GFAP) followed by accumulation of tangles (plasma P-tau) and later evidence of neurodegeneration (plasma NfL; A/T/N).2,5,39 These results remain to be replicated in larger cohorts and further studies are needed to investigate whether plasma GFAP also correlates to or can predict astrocytic activation.