NEFL and neurodegenerative disease: In a complete longitudinal PPMI cohort study, a large dataset of NF-L measurements by Simoa or ELISA was obtained from: (i) 176 CSF samples, including newly diagnosed and drug-naïve PD patients and controls, (ii) 1190 sera from patients with PD (including newly diagnosed and drug-naïve patients) (iii) other neurodegenerative diseases, (iv) subjects with prodromal conditions and mutation carriers as well as sera form healthy controls, [35].