NEFL and Alzheimer disease: The results indicated significantly raised levels of Aβ40 (p = 0.002), GFAP (p = 0.01), Nf-L (p = 0.04), and p-tau181 (p = 0.00005) in AD patients, even after adjusting for age-related variations in Nf-L and GFAP (Table 1).