Relationship between plasma NFL and disease progression in Parkinson’s disease: a prospective cohort study

Objective We aimed to examine the longitudinal change of plasma neurofilament light chain (NFL) level and explore its diagnostic and prognostic implications in Parkinson’s disease (PD). Methods A total of 184 patients with early PD who completed 5-year annually repeated clinical assessments were included. Plasma NFL at baseline, 1 year, and 2 year were examined, which were quantified using the ultrasensitive Simoa technology. At baseline, blood from 86 sex- and age-matched healthy controls (HC) were obtained for comparison. Results Plasma NFL in PD patients at baseline was significantly higher than those in HC ( P = 0.046), and significantly increased after 2 years ( P = 0.046). Receiver operating characteristic curve indicated that a plasma NFL cut-off value of 10.79 pg/mL resulted in 39.7% sensitivity and 84.0% specificity, with an area under the curve of 0.635, to distinguish PD from HC ( P < 0.001). Linear mixed-effect models indicated that baseline plasma NFL (> 9.24 pg/mL) correlated with a greater increase in the Unified Parkinson’s Disease Rating Scale III (estimate = 0.651, P = 0.001) and Hoehn & Yahr stage (estimate = 0.072, P < 0.001), and also correlated with a greater decrease in the Montreal Cognitive Assessment (estimate = − 0.387, P < 0.001) during follow-up visits. Conclusions Plasma NFL exhibits a tendency to increase with disease progression, and elevated baseline plasma NFL can serve as a predictor for accelerated motor deterioration and cognitive decline in PD. However, plasma NFL does not have high accuracy to distinguish individuals with early-stage PD from HC.