Review
Prevalence of dementia and major dementia subtypes in the Chinese populations: A meta-analysis of dementia prevalence surveys, 1980–2010

https://doi.org/10.1016/j.jocn.2012.01.029Get rights and content

Abstract

The aim of this study was to determine the prevalence of dementia and its major subtypes in China. Forty-eight eligible studies were included in this review. The pooled prevalence for the population aged 60 years and older of Alzheimer’s disease (AD) was 1.9%, vascular dementia (VaD) was 0.9%, and total dementia was 3.0%. The prevalence of VaD was significantly higher in Northern China than in Southern China. The prevalence of VaD was significantly higher in urban compared to rural areas. The prevalence of dementia and prevalence of AD increased with age in both males and females, and a higher prevalence of AD than VaD was observed in all age groups. AD has become more common than VaD in China since 1990. The current prevalence of dementia in China may be similar to that of developed countries.

Introduction

By the end of 2008, the elderly Chinese population, aged 60 years of age and above, had reached 159.89 million, accounting for 12% of the total Chinese population. This age group is predicted to reach 457 million by 2050. With this rapid growth in the elderly Chinese population, the prevention and treatment of age-related chronic diseases is of growing importance. Dementia is a disease of particular concern because the decline in memory and other cognitive functions that characterize this condition also lead to a loss of independent function that has a wide-ranging impact on individuals, families, and healthcare systems.

An accurate national estimate of the prevalence of dementia is essential for effective planning for long-term care and medical costs that will fall on the social security system Medicare, and other insurance programs for elderly adults in China. The aim of the present study was to perform a systematic analysis of published epidemiological studies on the prevalence of dementia in the elderly Chinese population from 1980 to 2010.

Section snippets

Literature search

The databases used in this meta-analysis [Chongqing VIP (1989–), CNKI (1979–), CBMDISK (1980–), and MEDLINE (1966–)] were inclusive up to October 2009. The core search terms used were “dementia”, “Alzheimer’s disease” (AD), “vascular dementia” (VaD), “epidemiological survey”, and “prevalence”. When possible, the authors of the included studies were contacted to ascertain their knowledge of unpublished data. The present study includes epidemiological studies in the Hong Kong area.

Inclusion criteria

All included studies met the following four selection criteria: (i) case collections were based on field surveys; (ii) studies were based on population samples; (iii) case collections were conducted in two stages: screening and diagnostic phases; and (iv) all samples were screened with brief cognitive tests, such as the Mini Mental State Examination, the Hasegawa Dementia scale, or the Blessed Dementia Scale. Those who were screen positive were scored below a given cutoff point on one or two

Data extraction

Two observers assessed the eligibility of the studies independently. Disagreements between the reviewers were resolved through discussion. Data were extracted by the same reviewers using a standardized data extraction form created for the present study and with help from others as needed. The following data were obtained from each study: first author’s name, journal and year of publication, place of study, and prevalence data. The authors of primary studies were asked to check the accuracy of

Data analysis

All meta-analyses were analyzed using Comprehensive Meta Analysis, a software package developed by BioStat International (Tampa, FL, USA).

Results

The search strategy identified 73 articles. After the obviously irrelevant abstracts were removed, the full texts of the remaining 66 studies were obtained. Forty-eight articles satisfied all inclusion criteria (Table 1). Twenty-five articles were excluded mainly because they were not original descriptions of population prevalence. The 48 selected studies covered 21 provinces and municipalities in China. A total elderly population of 105,866 was investigated, and 2,920 patients with dementia

Chronological prevalence of dementia

Data were classified into five groups (Table 2) based on the study years. The prevalence of dementia increased markedly from 1.3% in 1985–1990 to 3.9% in 2001–2005, but decreased slightly in 2006–2010. The prevalence of AD showed an almost identical tendency in 1985–2000. In 2006–2010, AD prevalence was 2.3%, equal to that in 2001–2005. The prevalence of VaD increased considerably from 0.4% in 1991–1995 to 1.1% in 2001–2005, but decreased in 2006–2010.

Prevalence of dementia with respect to age

The prevalence of dementia increased with age, from 1.0% of those aged 60–64 years to 26.3% of those aged 85 and older (Table 3). The prevalence of AD increased with age in both males and females. The result shows that the prevalence of AD in females was higher than in males in every age group. The prevalence of VaD increased from those aged 65–69 years to the group aged 85 years and older. A higher prevalence of AD than VaD was observed in all age groups.

Prevalence of dementia in different regions

The prevalence of dementia was analyzed in different regions to determine the geographical characteristics of this disease in China (Table 4). The prevalence of AD was slightly higher in Northern than in Southern China, whereas that of VaD was markedly higher in Northern than in Southern China. The prevalence of AD was slightly higher in rural China than in the city, whereas that of VaD was significantly higher in urban than in rural China.

Discussion

Forty-eight eligible studies, published between 1980 and 2010, were included in the current meta-analysis. A total elderly Chinese population of 105,866 was investigated, and 2,920 patients with dementia were detected. Among these patients, those with AD numbered 1,830, whereas VaD accounted for 905. The proportions of AD and VaD were 62.8% and 30.9%, respectively. The combined pooled prevalence in the elderly population aged 60 years and older was 3.0% for dementia; 1.9% for AD; and 0.9% for

Conflict of interest/disclosures

The authors declare that they have no financial or other conflicts of interest in relation to this research and its publication.

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