GFAP and Schnyder corneal dystrophy: Second, we compared the plasma Aβ42/Aβ40, plasma p-Tau181, plasma GFAP, plasma NfL, Aβ PET, tau PET, hippocampal volume, and temporal-MetaROI cortical thickness between normal control (NC), subjective cognitive decline (SCD), MCI, and dementia groups.