As stated above, a growing body of research has revealed that there is abnormal brain cholesterol metabolism in the brain in aging human and animals, SAMP8 mice, diabetic mice, FAD (5xFAD and APP/PS-1) animals, AD patients, genetic forms of AD animals and patients (ApoE4 allele, mutation of NPC1 or NPC2, polymorphism or mutations of ABC transporter and LDL receptor family). The gene discussed is LDLR; the disease is Alzheimer disease.