RBD: rapid eye movement sleep behavior disorder; PD: Parkinson's disease; UPDRS: Unified Parkinson's Disease Rating Scale; PSQI: Pittsburgh Sleep Quality Index; BDI: Beck Depression Inventory; BAI: Beck Anxiety Inventory; hs-CRP: high-sensitivity C-reactive protein; LDL: low-density lipoprotein; TAC: total antioxidant capacity; GSH: elevated total glutathione; NMSS: Non-Motor Symptoms Scale; PDQ-39: Parkinson's Disease Quality of Life-39. Here, CRP is linked to depressive symptom measurement.