Most published studies used data form the Alzheimer's Disease Neuroimaging Initiative (ADNI) where the cohort consists of predominantly LOAD patients: APOE ε4 accelerated hippocampal atrophy in AD, however, there is not enough evidence for the relationship between APOE ε4 and cognitive decline [16, 36]. Here, APOE is linked to early-onset autosomal dominant Alzheimer disease.