A study found that the number of NEP-positive cells in the hippocampus of D-gal/AlCl3 mice in the ligustrazine group was significantly higher than that of mice in the control group, which indicated that ligustrazine could increase the expression of NEP, promote the clearance of Aβ, and thus play a role in the prevention and treatment of AD (Liu Z. et al., 2016). This evidence concerns the gene MME and Alzheimer disease.