NEFL and Parkinson disease: CSF Gal-1 levels in the PD group were positively correlated to CSF concentrations of total tau (rho = 0.53, p < 0.001), phosphorylated tau (rho = 0.54, p < 0.001), and NFL (rho = 0.58, p < 0.0001), but α-syn levels were not significantly correlated to Gal-1 (rho = − 0.11, p = 0.5).