The levels of free radicals, including NO, H2O2, and ·OH, inflammatory factors, including IL-1β, IL-6, TNF-α, PGE2, and INF-γ, and pathological proteins, including α-synuclein, Aβ1−42, P-tau (T181), P-tau (S199), P-tau (T231), P-tau (S396), and total tau (T-tau),in the serum from PD patients were measured by using chemical colorimetric method and ELISA. Here, IL6 is linked to Parkinson disease.