Dementia (the English name “dementia” comes from Latin) is a progressive brain dysfunction, the gradual reduction of intelligence, seriously affecting the ability to live With the aging of the population in society, the prevalence of dementia is getting higher and higher, and the world’s experts say that dementia is a “price that must be paid by the people in order to increase the life expectancy of the whole society, and this price is as terrible as facing cancer and AIDS disease”. Dementia has been described by experts around the world as “the price that people have to pay to improve their life expectancy and society as a whole, a price that is as frightening as confronting cancer and AIDS”. The prevalence of Alzheimer’s disease in different age groups can tell how prevalent the disease is, the prevalence of 65-69 year olds is only 2%; 75-79 year olds reach 5%; 85-89 year olds reach 20%; 1/3 of the elderly people over the age of 90 years old have varying degrees of dementia. Moreover, it is found that more than half of these dementias are Alzheimer´s disease.