APOE and Alzheimer disease: However, in a study to examine the relationship of important AD intermediate phenotype such as differences in brain volume, hippocampal volume and cerebrovascular risk factors, and APOE4 among MCI subtypes, He and colleagues found CVD risk factors to be more closely related to nonamnestic MCI and vascular dementia; though emphasized that the biological differences between amnestic (AD group) and nonamnestic (presumed vascular etiology) were very subtle [34].