TF and Parkinson disease: There was neither a significant difference in TF total protein concentrations (2.10 μg/μl, IQR 1.65–2.86 vs. 2.07 μg/μl, IQR 1.31–2.75; p = 0.64) nor in sum wetting length (15 mm, IQR 8–24 vs. 15 mm, IQR 8–28; p = 0.55) comparing PD and CTR.