MAPT and Parkinson disease: Cross-sectionally Significant associations were observed between baseline NfL and other CSF biomarkers both in the HC (T-tau, β = 0.484, p < 0.001; P-tau, β = 0.540, p < 0.001; α-syn, β = 0.506, p < 0.001) and PD patients (T-tau, β = 0.247, p < 0.001; P-tau, β = 0.256, p < 0.001; α-syn, β = 0.192, p = 0.013; Aβ42, β = 0.182, p = 0.027).