The prevalence of dementia in the People's Republic of China: a systematic analysis of 1980-2004 studies

Background dementia has been a major public health problem. However, there has not yet been a nationwide investigation or systematic analysis of the prevalence of dementia in China from 1980 to 2004. Objectives the aim of this study was to analyse the prevalence of dementia and its major subtypes [Alzheimer disease (AD), vascular dementia (VD)] among the population aged 60years and older in China from 1980 to 2004. Methods epidemiological investigations on dementia in China published in journals and covering the period from 1980 to 2004 were identified manually and on-line by using CBMDISK, Chongqing VIP database and CNKI database. Those reported in English journals were identified using MEDLINE. Selected studies had to describe an original study defined by strict screening and diagnostic criteria. The fixed effects model or random effects model was employed according to statistical test for homogeneity. Results twenty-five studies were selected, the statistical information of which was collected for systematic analysis. Our results showed that AD and VD were the two major subtypes of dementia in China, and the pooled prevalence of AD and VD for the population aged 60years and older was 1.6 and 0.8%, respectively. There was a higher prevalence of AD in the illiterate elderly population (3.2%) than in those who received years of education. The chronological prevalence of AD increased significantly from 1980 to 2004. In southern and northern China, the prevalence of AD was 2.0 and 1.2%, respectively, while VD was 0.6 and 1.1%, respectively. Conclusions in the last 24years, AD and VD were the two major subtypes of dementia in China. The prevalence of AD may be affected by sex, education, occupation or age. The prevalence of VD, which was higher in northern than in southern China, seems not to be affected by age, sex or education.