Studies have clarified that Rg1 can directly decrease the p-Tau level, Aβ generation, and amyloid precursor protein (APP) expression; increased the content of the brain-derived neurotrophic factor (BDNF); and attenuated hippocampal histopathological abnormalities to improve the cognitive capability in AD rodent models [53,54,55,56,57,58,59]. The gene discussed is BDNF; the disease is Alzheimer disease.