Dementia subtypes in China - Prevalence in Beijing, Xian, Shanghai, and Chengdu

Background: Prevalences of Alzheimer disease (AD) and vascular dementia (VaD) in China reportedly differ from those in Western countries. Objective: To estimate prevalence of AD and VaD in 4 regions of China. Design: Cross-sectional, population-based prevalence survey with a stratified, multistage cluster sampling design. Setting: Rural (n = 99) and urbanized (n = 71) communities of Beijing, Man, Shanghai, and Chengdu. Participants: A sample of 34807 community residents (94% of those eligible) 55 years or older. Main Outcome Measures: Participants were screened with the Chinese Mini-Mental State Examination. Those who screened positive (n = 3950) underwent a standardized diagnostic workup. Screening sensitivity was assessed in a 3.3% random sample (n = 1008 of the 30857 who passed the screening). Diagnoses of AD and VaD were made according to National Institute of Neurological and Communicative Diseases and Stroke-Alzheimer Disease and Related Disorders Association and National Institute of Neurological Disorders and Stroke Association Internationale pour la Recherche et l'Enseignement en Neurosciences criteria, respectively. Final diagnoses were made after a 6-month confirmation interval. Results: We identified 732 AD cases and 295 VaD cases. Prevalence in persons 65 years or older was 3.5% (95% confidence interval, 3.0%-3.9%) for AD and 1.1% (95% confidence interval, 0.9%-1.1%) for VaD. After post hoc correction for negative screening errors, prevalence increased to 4.8% for AD and remained at 1.1% for VaD. Conclusion: Prevalence of dementia subtypes in China is comparable with that in Western countries.