GFAP and Alzheimer disease: CU, MCI, AD: normal cognitive function, mild cognitive impairment, and Alzheimer’s disease, respectively; MMSE, Mini-Mental State Examination; MoCA, Montreal Cognitive Assessment; GFAP, glial fibrillary acidic protein; NfL, neurofilament light; a = CU vs. MCI (p<0.05), b = CU vs. AD (p<0.05), c = MCI vs. AD (p<0.05)