TNFRSF9 and Parkinson disease: Higher levels of CCL23, TGF-alpha, and TNFRSF9 were related to cognitive status at follow-up, being higher in cognitively impaired PD patients (CCL23: t(27) = 2.737, p = 0.01; TGF-alpha: t(27) = 3.426, p < 0.01; TNFRSF9: t(27) = 2.432, p = 0.02; Figure 2 and Figure 4).