NEFL and Parkinson disease: CSF NfL levels resulted higher in CBS (n = 26) when compared to healthy controls (n = 118; p < 0.01) [25], and in CBS (n = 21) compared with PD (n = 29, p < 0.01), PD-MCI (n = 19, p < 0.01) [31], but lower when comparing CBS (n = 26) to ALS (n = 68, p < 0.01) [25].