NEFL and Parkinson disease: The diagnostic utility of blood NfL to separate patients with PD from patients with APD has not been studied previously, but several publications have shown that the levels of NfL in CSF can be used to distinguish between these disorders with AUCs of about 0.85–0.90.5, –, 7 Although a number of other CSF biomarkers and biomarker panels have been suggested to differentiate PD from ADP,5, –, 7 blood biomarkers offering sufficient diagnostic accuracy are unavailable besides NfL.