For the PD-only cohort (without APS), improvement in the MDS-UPDRS III after PD-MCT correlated positively with MDS-UPDRS III at admission (r = 0.37; p < 0.001) and negatively with depression (rs = −0.23; p = 0.011) but not with age (p = 0.176), sex (p = 0.512), LEDD (p = 0.632), Hoehn & Yahr stage (p = 0.102), disease duration (p = 0.852), NMSQ (p = 0.631), or MoCA (p = 0.081). This evidence concerns the gene DOCK3 and major depressive disorder.