MAPT and Parkinson disease: In the comparison of measured biomarker levels for 5 years, PD patients with low Aβ1-42 showed significantly lower CSF α-syn (estimate − 438.43, SE 83.41, p < 0.001), t-tau (estimate − 40.66, SE 7.21, p < 0.001) and p-tau levels (estimate − 2.64, SE 0.71, p < 0.001), whereas serum NfL did not exhibit significant difference (Supplementary Table S2).