Evidence also show an impairment in VEGF protein expression in AD, with mainly an upregulation in the brain (Thomas et al., 2015; Miners et al., 2016), but contrasted results in the periphery, with up- or downregulation in the serum (Mateo et al., 2007; Huang et al., 2013; Cho et al., 2017; Liang et al., 2021). This evidence concerns the gene VEGFA and Alzheimer disease.