PMC CVR could be a good avenue for further investigation, given alterations in older APOE E4 carriers and increased permeability of the blood-brain-barrier in AD and APOE E4 carriers (Korte et al., 2020; Montagne et al., 2020; Tai et al., 2016; Thambisetty et al., 2010). This evidence concerns the gene APOE and Alzheimer disease.