IL6 and Parkinson disease: In this study, HAMD-24 was used to assess the depressive symptoms of PD patients; the levels of neuroinflammatory factors, including hydrogen peroxide (H2O2), nitric oxide (NO), tumor necrosis factor (TNF)-α, IL (interleukin)-1β, IL-6, prostaglandin (PG)E2, and neurotransmitters, including DA, 5-HT, and NE in CSF, were measured and compared between PD-D and PD-ND groups; the correlations among the score of HAMD-24, the levels of neuroinflammatory factors, and neurotransmitters in PD-D group were analyzed.