Over the sparsity range 0.10–0.40 (step =0.01), both the PD‐high‐GDNF and PD‐low‐GDNF groups exhibited reduced Cp (p = 0.019) and low‐efficiency small‐world topology (sigma = gamma (Cp)/ lambda (Lp); p = 0.008) (Figure 2; Table 2). Here, GDNF is linked to Parkinson disease.