NEFL and Alzheimer disease: Clinical studies have shown that AD-related plasma biomarkers, such as plasma amyloid-β (Aβ) 42/40 ratio, phosphorylated tau181 (p-tau181), glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL), are correlated with the load of AD pathology in central nervous system (CNS) and accelerated progression of the disease [2–7].