Prevalence of Alzheimer's disease,a neurodegenerative disease of the central nervous system,is increasing with the aging of population,causing serious social and family burdens.It is influenced by a variety of factors,including genetic and environmental ones.Epigenetics is an important bridge connecting genetic and environmental factors.DNA methylation,the most important modification in epigenetics,is related to many diseases like aging,cancer and dementia.In this paper,we reviewed the recent studies on the role ofDNA methylation in AD.

Objective To know about the status of hypertension among Mongolian and Han aged older than 55 years living in pastoral area of the Inner Mongolia Autonomous Region.Methods Stratified sampling method was adopted and 9146 people aged 55 years or older were selected,blood pressure measurement and related information were collected,prevalence,awareness,treatment and control rates of hypertension were analyzed.Results The hypertension crude prevalence rate of Mongolian and Han subjects was 54.10％ ( standardized prevalence rate was 53.93％ ),in which,the Mongolian and Han subjects crude hypertension prevalence rate was 52.96％ and 54.73％ respectively (standardized prevalence rate was 53.44％ and 55.08％ respectively),and there was no statistically significant ( P =0.104).Among the male gender,awareness rate,treatment rate and control rate of hypertension was 61.03％,46.73％ and 11.87％ respectively.Among the female gender, awareness rate, treatment rate and control rate of hypertension was 67.58％,56.55％ and 14.03％ respectively.Among Mongolian and Han subjects,difference of hypertension prevalence of different age groups was statistically significant( P values were 0.032 and 0.000),Among Mongolian subjects,difference of hypertension awareness of different age groups was statistically significant ( P =0.000 ).Among Han subjects,difference of hypertension awareness rates,treatment rates,and control rates of different age groups were statistically significant( P values were 0.000,0.047 and 0.043 ).Conclusion Hypertension prevalence rate among Han and Mongolian people older than 55 years living in pastoral area of Inner Mongolia Autonomous Region is high while the awareness,treatment and control rates of hypertension are rather low.