Although the specific mechanism has not been fully elucidated, apolipoprotein A-I (apoA-I), which is the most abundant lipoprotein in HDL, and discoidal HDL, have a protective effect in AD pathology, including amelioration of Aβ deposition and memory reduction as well as the antioxidant effect in preclinical studies [41,42,43,44]. The gene discussed is APOA1; the disease is Alzheimer disease.