Association Between Longitudinal Plasma Neurofilament Light and Neurodegeneration in Patients With Alzheimer Disease

Plasma neurofilament light (NfL) has been suggested as a noninvasive biomarker to monitor neurodegeneration in Alzheimer disease (AD), but studies are lacking.

To examine whether longitudinal plasma NfL levels are associated with other hallmarks of AD. Design, Setting, and Participants: This North American cohort study used data from 1583 individuals in the multicenter Alzheimer's Disease Neuroimaging Initiative study from September 7, 2005, through June 16, 2016. Patients were eligible for inclusion if they had NfL measurements. Annual plasma NfL samples were collected for up to 11 years and were analyzed in 2018. Exposures: Clinical diagnosis, Aβ and tau cerebrospinal fluid (CSF) biomarkers, imaging measures (magnetic resonance imaging and fluorodeoxyglucose-positron emission tomography), and tests on cognitive scores. Main Outcomes and Measures: The primary outcome was the association between baseline exposures (diagnosis, CSF biomarkers, imaging measures, and cognition) and longitudinal plasma NfL levels, analyzed by an ultrasensitive assay. The secondary outcomes were the associations between a multimodal classification scheme with Aβ, tau, and neurodegeneration (ie, the ATN system) and plasma NfL levels and between longitudinal changes in plasma NfL levels and changes in the other measures.