It is also unclear how BPV may be related to medial temporal atrophy rates in those at risk for AD due to the presence of the apolipoprotein ε4 (APOE ε4) gene, which has been associated with neurodegeneration and neurovascular deficits in the hippocampus and parahippocampal cortex (Burggren et al., 2008; Palop & Mucke, 2011). This evidence concerns the gene APOE and Alzheimer disease.