In addition, our baseline findings of higher plasma p-tau181 concentration in the PD group compared with controls and non-significant differences in plasma NfL concentration might reflect what has been showed in a recent study assessing the temporal trajectories of fluid biomarkers in a de novo PD cohort: at baseline, CSF p-tau but not serum NfL concentration was significantly higher in patients than in the control group while, over time, the increase observed in NfL concentration was much higher than the increase observed in p-tau concentration38. This evidence concerns the gene NEFL and Parkinson disease.