As we reviewed the potential dual impact of VEGF and found that the causal linkage of VEGF in PD is less clear than that of other age-related neurological diseases such as ALS (e.g., VEGFd/d mice [2]) and AD (e.g., two-hit hypothesis [36,77,78]), we asked what the relationship would be between vascular stiffness and neurological disorders. The gene discussed is VEGFA; the disease is Parkinson disease.