NEFL and Alzheimer disease: The main findings of this study are that (1) plasma NFL/Aβ1–42 was correlated with CSF NFL/Aβ1–42 and hippocampal volume/ICV, (2) plasma NFL/Aβ1–42 was associated with higher diagnostic accuracy in the early stage of AD, and (3) plasma NFL/Aβ1–42 changed more rapidly than CSF t-Tau and CSF p-Tau181 concentrations in the preclinical stage of AD.