REN and Alzheimer disease: VEGF is mostly known for its involvement in angiogenesis, and besides participating in brain vasculature regulation, it influences neurogenesis and neuronal regeneration.17 In Alzheimer’s disease, upregulation of VEGF might reflect attempts to compensate for a dysfunctional vasculature.17 Conversion of AGT to Angiotensin I by renin is one of the first steps in the renin–angiotensin system (RAS).