EGF and Parkinson disease: No differences were found between the PD and control groups in age (63.37 ± 8.99 vs. 62.96 ± 6.37, t = 0.372, P = 0.710) or sex (56% vs. 52%, c2 = 0.322, P = 0.570), while serum IGF-1 and EGF levels were significantly higher in the PD patients than in the healthy controls (IGF-1: 149.50 ± 33.85 mmol/L vs. 99.06 ± 21.29 mmol/L, P < 0.001; EGF: 62.96 ± 11.72 pg/mL vs. 52.22 ± 9.24 pg/mL, P < 0.001) (Table 1).