ADO and Parkinson disease: The LSD pairwise comparison revealed ADO, GDNF, and γ-GABA levels in the PD-SD group (13.18 ng/mL, 287.55 pg/mL, 37.21 ng/mL) were lower than those in the PD-NSD group (16.96 ng/mL, 392.81 pg/mL, 39.22 ng/mL) and HC group (19.07 ng/mL, 453.56 pg/mL, 43.68 ng/mL) respectively (Figure 2a–c).