GCH1 and psychiatric disorder: On the other hand, Timmers et al. (2017), after also highlighting that in DRD patients the occurrence of NMS is expected, found a higher lifetime prevalence of psychiatric disorders (61% vs. 29%, p < 0.05) and daytime sleepiness (11.2 vs. 5.7, p < 0.05) in a cohort of Dutch adults with DYT/PARK-GCH1, but not in children, compared to matched controls [16].