Alzheimer's disease (AD) is a progressive neurodegenerative disease with insidious onset. In clinical practice, comprehensive dementia is characterized by memory impairment, aphasia, recognition loss, impairment of visual and spatial skills, executive dysfunction, and personality and behavioral changes. According to the statistics, the global prevalence of dementia will be as high as 24 million, and is predicted to double every 20 years until at least 2040 [1]. The etiology of Alzheimer disease remains unclear, but most people think it is result of both genetic and environmental factors. How to cure this kind of disease has become a big trouble for decades.