It is well known that age is the greatest risk factor (AD increases exponentially with age in people aged 65 or older) [68], together with some other factors as (1) allelic variations in apolipoprotein E (Apo E), (2) degeneration of anatomical pathways, (3) mitochondrial dysfunction, (4) compromised blood-brain barrier, (5) immune system dysfunction, (6) infectious agents and other environmental factors such as exposure to aluminium, (7) repeated head injury, and (8) malnutrition [69]. The gene discussed is APOE; the disease is Alzheimer disease.