In this study, we used db/db mouse as a DACD animal model, since it is reported that db/db mouse, an animal model of type 2 diabetes mellitus (T2DM), exhibits not only obesity, hyperglycemia, hyperinsulinemia, leptin and insulin resistance but also impaired hippocampus-dependent cognitive performance [5]. The gene discussed is LEP; the disease is type 2 diabetes mellitus.