IFNG and Parkinson disease: An increase in serum IFNγ and IL-10 with varying disease durations (< 1-year PD (n = 12); 1–3 years PD (n = 30); 3–12 years PD (n = 30)) was overall observed in the PD patients in comparison to healthy controls (P < 0.0001) (Fig. 1); Conversely, serum TNFα showed a significant increase at early PD (first twelve months) which gradually declined to near zero with disease duration (P < 0.001) compared to healthy controls.