A multicentre community-based study of dementia cases and subcases in older people in China--the GMS-AGECAT prevalence and socio-economic correlates

Spatial disparity and factors associated with dementia mortality: A cross-sectional study in Zhejiang Province, China

Objective

Evidence of spatial disparity in dementia mortality in China has been found to have higher dementia mortality in eastern and rural China. Regional factors of physical and social features may be influencing this spatial disparity. However, the extent of spatial difference in dementia mortality across small regional localities is unclear. This study aims to investigate the geographic variations in mortality and risk of all dementia subtypes and identify the effect of the associated environmental risk factors.

Methods

We used surveillance data on death reports from Alzheimer's disease and other forms of dementia in Zhejiang province from 2015 to 2019. We estimated the relative risk of dementia mortality using a Bayesian spatial model. We mapped predicted relative risk to visualize the risk of death from different types of dementia and to identify risk factors associated with dementia.

Results

Thirty thousand three hundred and ninety-eight deaths attributable to dementia as the underlying or related cause (multiple causes) were reported during 2015-2019. Counties and districts in the southeast and west of Zhejiang province had significantly higher standardized mortality ratios than others. Counties and districts with a smaller proportion of residents aged 60 years or older, poorer economic status, insufficient health resources, and worse pollution had a higher risk of deaths due to dementia.

Conclusion

Higher risks of dementia mortality were found in counties and districts with poorer economic status, insufficient health resources, and worse pollution in Zhejiang. Our study adds new evidence on the association between socioeconomic and environmental factors and the mortality risk due to dementia.

Impact of fish consumption on all-cause mortality in older people with and without dementia: a community-based cohort study

BACKGROUND

Increased fish consumption reduces the risk of dementia. However, it is unknown whether fish consumption reduced all-cause mortality in people with dementia. The purpose of the study is to investigate the association of fish consumption with all-cause mortality in older people with dementia versus those without dementia.

METHODS

Using a standard method of the Geriatric Mental State, we interviewed 4165 participants aged ≥ 60 years who were randomly recruited from five provinces in China during 2007-2009 to collect the baseline data of socio-demography, disease risk factors, histories of disease, and details of dietary intakes, and diagnosed dementia (n = 406). They were followed up for vital status until 2012.

RESULTS

The cohort follow-up documented 329 deaths; 61 were in participants with dementia (55.3 per 1000 person-years) and 224 were those without dementia (22.3). In all participants, the risk of all-cause mortality was reduced with fish intake at " ≥ twice a week" (multivariate-adjusted hazard ratio 0.58, 95% CI 0.34-0.96) and at "once a week or less" (0.79, 0.53-1.18) compared to "never eat" over the past two years. In participants without baseline dementia, the corresponding HRs for all-cause mortality were 0.57 (0.33-0.98) and 0.85 (0.55-1.31), while in participants with dementia were 1.36 (0.28-6.60) and 1.05 (0.30-3.66), respectively.

CONCLUSION

This study reveals that consumption of fish in older age reduced all-cause mortality in older people without dementia, but not in people with dementia. Fish intake should be increased in older people in general, prior to the development of dementia in the hope of preventing dementia and prolonging life.

Model-Based Projection of Dementia Prevalence in China and Worldwide: 2020-2050

BACKGROUND

Current and future incidence and prevalence estimates of dementia are essential for public health planning.

OBJECTIVE

The objective was to establish prediction model of incidence and estimate the prevalence of dementia in the Chinese and worldwide population from 2020 to 2050.

METHODS

A model-based method was used to project the dementia prevalence from 2020 to 2050 in China, which required incidence, the mortality rate for individual without dementia, and the relative risk of death. Furthermore, we detected the impact of intervention on the prevalence projection for dementia using a simulation method. We applied the same method to other projections worldwide.

RESULTS

In 2020, the model predicted 16.25 million (95%confidence interval 11.55-21.18) persons with dementia in China. By 2050, this number would increase by approximately three-fold to 48.98 million (38.02-61.73). Through data simulation, if the incidence of dementia decreased by 10%every 10 years from 2020 after intervention and prevention, the number of dementia cases by 2050 was reduced by 11.96 million. This would reduce the economic burden by US $639.04 billion. In addition, using this model, dementia cases grew relatively slowly over the next few decades in the United States of America, the United Kingdom, and Japan, with percentage changes of 100.88%, 65.93%, and 16.20%, respectively.

CONCLUSION

The number of people with dementia in China is large and will continue to increase rapidly. Effective interventions could reduce the number of patients drastically. Therefore, prevention and control strategies must be formulated urgently to reduce the occurrence of dementia.

Association between socioeconomic status and incident stroke in China

Background

Little is known about the impact of socioeconomic status (SES) on incidence of stroke in China. This study aimed to examine the association of SES, which was measured by different indicators, with incidence of stroke and gender differences in the association.

Methods and results

Two prospective cohort studies were conducted including 2852 participants aged ≥60 years in Anhui province and 3016 participants in four other provinces in China. During a median follow-up of 7.1 years, 211 incident stroke cases occurred in the Anhui cohort. The risk of stroke increased with living in rural areas (adjusted HR 2.49, 95% CI 1.19 to 5.22; women 3.64, 95% CI 1.17 to 11.32, men 2.23, 95% CI 0.81 to 6.19), but not significantly with educational level, occupational class, satisfactory income and financial problems (except for women with low education). The four-province cohort had 113 incident stroke cases over the 3.1 years’ follow-up. The five SES indicators were not significantly associated with incident stroke (except for increased risk in men with high occupation), but additional measurement for actual income showed that incident stroke increased in women with low personal income and in men with high family income. Pooled data from the two cohorts demonstrated the impacts of rural living (1.66, 95% CI 1.08 to 2.57) and having high occupational class (1.56, 95% CI 1.01 to 2.38), and gender differences for women with low education (2.26, 95% CI 1.19 to 4.27).

Conclusions

Rural living and being female with low SES are associated with increased stroke risk in China. Strategies to improve public health in the rural communities and gender-specific targets for health inequality should be an integral component of stroke interventions.

Socio-economic status and dementia onset among older Japanese: A 6-year prospective cohort study from the Japan Gerontological Evaluation Study

OBJECTIVES

Lower socio-economic status (SES) may be associated with dementia later in life, but there is inconsistent evidence supporting this claim. We aim to examine the association between three SESs (education, job, and income indicators) and dementia onset in older adults.

METHODS

Study design was a 6-year prospective cohort study. Participants included a total of 52 063 community-dwelling adults aged 65 years or older without long-term care needs from the Japan Gerontological Evaluation Study. Outcome variable was dementia onset. Explanatory variables were educational years, the longest job held, and equivalised household income. We performed Cox proportional hazard analysis by gender with multiple imputation.

RESULTS

During the follow-up period, 10.5% of participants acquired dementia. The adjusted risks of dementia incidence of the participants with less than 6 years of education were 1.34 times (95% confidence interval [CI], 1.04-1.73) in men and 1.21 (1.00-1.45) times in women higher than those with more than 13 years of education. Females with less than 1.99 million yen (hazard ratio = 0.83, 0.72-0.96) of equivalised income were less likely to acquire dementia than those with four million yen or higher.

CONCLUSIONS

Educational attainment had a robust impact on dementia onset compared with the other SES factors in both genders of older Japanese people. Securing an education for children could be crucial to prevent dementia later in life. The longest job held was less likely to be risks of dementia incidence, compared with the other two factors.

Dementia in China: epidemiology, clinical management, and research advances

China has the largest population of patients with dementia in the world, imposing a heavy burden on the public and health care systems. More than 100 epidemiological studies on dementia have been done in China, but the estimates of the prevalence and incidence remain inconsistent because of the use of different sampling methods. Despite improved access to health services, inadequate diagnosis and management for dementia is still common, particularly in rural areas. The Chinese Government issued a new policy to increase care facilities for citizens older than 65 years, but most patients with dementia still receive care at home. Western medicines for dementia symptoms are widely used in China, but many patients choose Chinese medicines even though they have little evidence supporting efficacy. The number of clinical trials of Chinese and western medicines has substantially increased as a result of progress in research on new antidementia drugs but international multicentre studies are few in number. Efforts are needed to establish a national system of dementia care enhance training in dementia for health professionals, and develop global collaborations to prevent and cure this disease.

The temporal trend and distribution characteristics in mortality of Alzheimer's disease and other forms of dementia in China: Based on the National Mortality Surveillance System (NMS) from 2009 to 2015

Background

China is experiencing rapid age, which will lead to increasing burden of age-related diseases, such as Alzheimer disease and other forms of dementia.

Objectives

The aim of this study was to 1) Explore the temporal trend of mortality of Alzheimer disease (AD) and other forms of dementia in China and 2) Analyze its geographic variations and urban-rural differences and calculate the years of life lost (YLLs) from AD and other forms of dementia.

Data and methods

Data were extracted from the National Mortality Surveillance System (NMS). Age-standardized mortalities were calculated with the Western Grade 26 Standard Life List, and the YLLs were calculated using the DALY template provided by the WHO / World Bank global burden of disease (GBD) Working Group. The trends in crude and age-standardized mortality of AD and other forms of dementia were examined using Cochran-Armitage trend test.

Results

In China, the crude mortality from AD and other forms of dementia increased from 2009 to 2015, but the age-standardized mortality decreased. The YLLs of AD and other forms of dementia increased during the study period. The age-standardized mortality in the east was higher than those in the west and middle regions, and the age-standardized mortality in rural areas was higher than that in urban areas.

Conclusion

In China, the age-standardized mortality of AD and other forms of dementia decreased from 2009 to 2015. However, the disease burden from AD and other forms of dementia is becoming heavier due to increasing elderly population. Moreover, there were geographic variations and urban-rural differences in mortality of AD and other forms of dementia in China.

Prevalence of dementia in mainland China, Hong Kong and Taiwan: an updated systematic review and meta-analysis

BACKGROUND

There are several existing systematic reviews of prevalence of dementia for mainland China, Hong Kong and Taiwan, but several studies have been newly reported. The aim of this study is to update prevalence data in this region and test for variation across geographical areas and time periods using the new dataset.

METHODS

Twenty prevalence studies identified from World Alzheimer Report 2015 (January 2011-March 2015) and an updated search (March 2015-February 2017) were added to the original dataset (N = 76). Meta-regression was used to investigate geographical variation and time trends, taking methodological factors and characteristics of study population into account, and to estimate prevalence and number of people with dementia by geographical area.

RESULTS

Compared with northern China, the prevalence of dementia was lower in the central China [-1.0; 95% confidence interval (CI):-2.2, 0.3], south China (-1.7; 95% CI: -3.1, -0.3), Hong Kong and Taiwan (-3.0; 95% CI: -5.0, -1.0) but appeared to be higher in western China (2.8; 95% CI: 0.1, 5.5) after adjusting for methodological variation. The increasing trend from pre-1990 to post-2010 periods was considerably attenuated when taking into account methodological factors and geographical areas. The updated estimated number of people with dementia in all these areas is 9.5 million (5.3%; 95% CI: 4.3, 6.3) in the population aged 60 or above.

CONCLUSIONS

Geographical variation in dementia prevalence is confirmed in this update, whereas evidence on increasing trends is still insufficient. Differing societal development across areas provides an opportunity to investigate risk factors at the population level operating across diverse life course experiences. Such research could advance global primary prevention of dementia.

Invited Commentary: Secondhand Smoke-an Underrecognized Risk Factor for Cognitive Decline

Pan et al. (Am J Epidemiol. 2018;187(5):911-918) reported findings that exposure to secondhand smoke (SHS) was associated with cognitive decline over the course of 2 years among middle-aged and older Chinese women who never smoked, and they also reported a dose-response relationship. SHS exposure affects vulnerable people disproportionately because they have less control or choice over their living and working environment. Smoking is an established risk factor for dementia, but recent evidence reports on dementia-risk increase have not included SHS. Many epidemiologic studies collect data on smoking but not SHS exposure. SHS may be one of the most prevalent and modifiable risk factors for cognitive decline and therefore represents a major potential target for reduction of dementia risk. Given the high prevalence of smoking in China and other parts of the world, there is an urgent need to raise awareness of SHS reduction as part of global and national strategies to reduce cognitive decline and dementia and to introduce legislation that protects nonsmokers and vulnerable children and adults from SHS.

Association between fish consumption and risk of dementia: a new study from China and a systematic literature review and meta-analysis

Objective

To assess the association of fish consumption with risk of dementia and its dose–response relationship, and investigate variations in the association among low-, middle- and high-income countries.

Design

A new community-based cross-sectional study and a systematic literature review.

Settings

Urban and rural communities in China; population-based studies systematically searched from worldwide literature.

Subjects

Chinese adults aged ≥60 years in six provinces (n 6981) took part in a household health survey of dementia prevalence and risk factors. In addition, 33 964 participants from eleven published and eligible studies were included in the systematic review and meta-analysis.

Results

In the new study in China, 326 participants were diagnosed with dementia (4·7 %); those who consumed any amount of fish in the past two years v. those who consumed no fish had reduced risk of dementia (adjusted OR=0·73, 95 % CI 0·64, 0·99), but the dose–response relationship was not statistically significant. The meta-analysis of available data from the literature and the new study showed relative risk (RR) of dementia of 0·80 (95 % CI 0·74, 0·87) for people with fish consumption; the impact was similar among countries with different levels of income. Pooled dose–response data revealed RR (95 % CI) of 0·84 (0·72, 0·98), 0·78 (0·68, 0·90) and 0·77 (0·61, 0·98) in people with low, middle and high consumption of fish, respectively. Corresponding figures for Alzheimer’s disease were 0·88 (0·74, 1·04), 0·79 (0·65, 0·96) and 0·67 (0·58, 0·78), respectively.

Conclusions

Greater consumption of fish is associated with a lower risk of dementia. Increasing fish consumption may help prevent dementia worldwide regardless of income level.

Prevalence and determinants of undetected dementia in the community: a systematic literature review and a meta-analysis

OBJECTIVES

Detection of dementia is essential for improving the lives of patients but the extent of underdetection worldwide and its causes are not known. This study aimed to quantify the prevalence of undetected dementia and to examine its correlates.

METHODS/SETTING/PARTICIPANTS

A systematic search was conducted until October 2016 for studies reporting the proportion of undetected dementia and/or its determinants in either the community or in residential care settings worldwide. Random-effects models calculated the pooled rate of undetected dementia and subgroup analyses were conducted to identify determinants of the variation.

PRIMARY AND SECONDARY OUTCOME MEASURES

The outcome measures of interest were the prevalence and determinants of undetected dementia.

RESULTS

23 studies were eligible for inclusion in this review. The pooled rate of undetected dementia was 61.7% (95% CI 55.0% to 68.0%). The rate of underdetection was higher in China and India (vs Europe and North America), in the community setting (vs residential/nursing care), age of <70 years, male gender and diagnosis by general practitioner. However, it was lower in the studies using Mini-Mental State Examination (MMSE) diagnosis criteria.

CONCLUSIONS

The prevalence of undetected dementia is high globally. Wide variations in detecting dementia need to be urgently examined, particularly in populations with low socioeconomic status. Efforts are required to reduce diagnostic inequality and to improve early diagnosis in the community.

Social class, dementia and the fourth age

Research addressing social class and dementia has largely focused on measures of socioeconomic status as causal risk factors for dementia and in observed differences in diagnosis, treatment and care. This large body of work has produced important insights but also contains numerous problems and weaknesses. Research needs to take account of the ways in which ageing and social class have been transformed in tandem with the economic, social and cultural coordinates of late modernity. These changes have particular consequences for individual identities and social relations. With this in mind this article adopts a critical gaze on research that considers interactions between dementia and social class in three key areas: (i) epidemiological approaches to inequalities in risk (ii) the role of social class in diagnosis and treatment and (iii) class in the framing of care and access to care. Following this, the article considers studies of dementia and social class that focus on lay understandings and biographical accounts. Sociological insights in this field come from the view that dementia and social class are embedded in social relations. Thus, forms of distinction based on class relations may still play an important role in the lived experience of dementia.

Social correlates of mental, neurological, and substance use disorders in China and India: a review

Understanding the epidemiological profiles of mental, neurological, and substance use disorders provides opportunities for the identification of high-risk population subgroups and for the development of effective country-specific prevention and intervention strategies. Guided by the Conceptual Framework for Action on the Social Determinants of Health by WHO we reviewed the literature to examine the association between a range of social correlates (eg, sex, age, education, income, urbanicity, marital status, and regional differences) and mental, neurological, and substance use disorders in China and India, the most populous countries in the world. We looked for papers on mental, neurological, and substance use disorders with location identifiers and socioeconomic correlates published between 1990 and 2015 and our search found 65 relevant studies from China and 29 from India. Several association patterns between social correlates and mental, neurological, and substance use disorders were not consistent with those reported in high-income countries, including a high concentration of middle-aged men with alcohol use disorders in China and to a lesser extent in India, and a positive association between being married and depression among women in India. Consistent with previous global reports, low education and poverty were associated with higher occurrence of dementia in both China and India, although there is evidence of an interaction between education and income in the risk for dementia in China. Large variations across regions and ethnic groups were consistently documented in China. These unique correlation patterns for mental, neurological, and substance use disorders identified in China and India emphasise the importance of understanding the local social context when planning targeted strategies to reduce the burden of these disorders. High-quality, up-to-date information about the constantly changing pattern of societal factors correlated with mental, neurological, and substance use disorders is urgently needed to help reduce the large and increasing negative social and economic effects that these conditions are having in China, India, and other low-income and middle-income countries.

Temporal Trends and Geographic Variations in Dementia Mortality in China Between 2006 and 2012: Multilevel Evidence From a Nationally Representative Sample

OBJECTIVES

We aimed to explore the temporal trends and geographic variations in dementia mortality in China.

MATERIALS AND METHODS

Annual dementia mortality counts (years 2006 to 2012) in 161 counties and districts (Disease Surveillance Points, DSP) were extracted from the nationally representative China Mortality Surveillance System and stratified by 5-year age group (aged >65), sex, and time. These counts were linked to annually adjusted denominator populations. Multilevel negative binomial regression with random intercepts and slopes were used to investigate spatiotemporal variation in dementia mortality.

RESULTS

Dementia mortality varied over 2-fold between DSPs (median rate ratio: 2.59). Significant variation in DSP slopes through time (variance 0.075, SE 0.020) indicated spatiotemporal variations. Mortality rates were significantly higher in the east (rate ratio 2.28; 95% confidence intervals, 1.45-3.60) compared with the north. There was a declining trend in 2 (east and northwest) of the 7 regions. Dementia mortality decreased by 15% in urban areas but increased by 24% in rural areas.

CONCLUSIONS

Our findings indicate that regional inequalities in dementia mortality are salient, and the increase in mortality rates in rural areas is an emerging public health challenge in China. Tailored preventive health strategies should be in place to narrow down this avoidable and wholly unnecessary inequality.

Income in midlife and dementia related mortality over three decades: A Norwegian prospective study

Studies on midlife income and dementia are scarce, and our main aim was to investigate midlife with later risk of dementia related mortality, adjusting for education and dementia related risk factors. The study population consisted of Norwegian men, aged 40–59 years in 1980 at income assessment, which participated in Norwegian health examination studies in the period 1980–2002 where risk factors such as cholesterol level, hypertension, smoking, cardiovascular disease, and diabetes were assessed. Dementia related mortality was defined as a dementia diagnosis on the death certificate until 2012. Cox regression was used. The study included 45,944 participants and 1062 dementia related deaths. There was no association between midlife income and dementia mortality risk (HR = 1.04, 95% confidence interval (CI) 0.85, 1.28 for the lowest fifth of income compared to those in the highest fifth). For total mortality, there was a strong inverse association with income (HR = 1.61, 95% CI 1.53, 1.69), which was attenuated when adjusting for education and risk factors, but still significant (HR = 1.27, 95% CI 1.20, 1.34). Lower educational attainment was significantly associated with increased dementia mortality risk, also after adjustment for income and other known risk factors (HR = 1.30, 95% CI 1.03, 1.64 comparing low versus high education). Midlife income was not associated with dementia related mortality, but low education was independently linked to increased risk of dementia related mortality. Our results support the cognitive reserve hypothesis suggesting that mental activity and not material resources are related to dementia related mortality.

Prevalence of dementia-associated disability among Chinese older adults: results from a national sample survey

OBJECTIVE

Due to rapid population aging and a tidal wave of dementia, dementia has become an urgent public health issue in China. Few large-scale surveys on dementia have been conducted in China and little was known about the magnitude of dysfunction and disability caused by dementia. In this study, using national sample survey data, we aimed to describe the prevalence rate of dementia-associated disability, its associated factors, and daily activities and social functions of people with dementia-associated disability in Chinese older adults.

METHODS

We used the second China National Sample Survey on Disability, comprising 2,526,145 persons from 771,797 households. Identification for dementia was based on consensus manuals. Standard weighting procedures were used to construct sample weights considering the multistage stratified cluster sampling survey scheme. Population weighted numbers, weighted prevalence, and the odd ratios (ORs) were calculated.

RESULTS

The prevalence rate of dementia-associated disability was 4.64% (95% CI: 4.26-5.01) and it accounted for 41.03% of mental disability among Chinese older adults. Urban residence (OR: 1.33 [1.12-1.57]), older age (80+ years) (OR: 4.12 [3.38-.03]), illiteracy (OR: 1.79 [1.27-2.53]), and currently not married (OR: 1.15 [1.00-1.32]) were associated with increased risk of dementia-associated disability. Compared with those with mental disability of other causes and those with other types of disabilities, older adults with dementia-asscoiated disability were more likely to have severe or extreme difficulty in daily activities and social functions.

CONCLUSION

Countermeasures are warranted to obtain a more precise overview of dementia in China, and strategies on enhancing early identification, treatment, and rehabilitation should be developed for people with dementia.

Period, birth cohort and prevalence of dementia in mainland China, Hong Kong and Taiwan: a meta-analysis

OBJECTIVE

There have been dramatic societal changes in East Asia over the last hundred years. Several of the established risk factors could have important period and cohort effects. This study explores temporal variation of dementia prevalence in mainland China, Hong Kong and Taiwan taking study methods into account.

METHODS

Seventy prevalence studies of dementia in mainland China, Hong Kong and Taiwan were identified from 1980 to 2012. Five period groups (before 1990, 1990 ~ 1994, 1995 ~ 1999, 2000 ~ 2004 and 2005 ~ 2012) and five birth cohort groups (1895 ~ 1909, 1910 ~ 1919, 1920 ~ 1929, 1930 ~ 1939 and 1940 ~ 1950) were categorised using the year of investigation and 5-year age groups. Pooled prevalence by age, period and birth cohort groups was estimated through meta-regression model and meta-analysis taking diagnostic criteria and age structure into account.

RESULTS

After adjusting for diagnostic criteria, the study age range and age structure, the prevalence of dementia in the older population aged 60 years and over fluctuated across periods but not reaching significance and were estimated as 1.8%, 2.5%, 2.1%, 2.4% and 3.1% for the five periods from pre-1990 to 2005 ~ 2012. A potential increasing pattern from less to more recent birth cohort groups was found in the major studies using older diagnostic criteria with wider differences in the age groups over 70 years.

CONCLUSIONS

This study found no significant variation across periods but suggested a potential cohort effect. The influence of societal changes might moderate early life experiences across different generations with substantial impact on mental health in older age.

The assessment of cognitive impairment suspected of dementia in Polish elderly people: results of the population-based PolSenior Study

The growing incidence of dementia in ageing societies is a major concern of health care organizations. Because of its detrimental influence on the mental and functional statuses of elderly people, it leads to increased economic burdens caused by the social and financial needs of patients with dementia and their caregivers. There has been no data concerning the prevalence of dementia in the elderly in the general Polish community so far. The main aim of the study was to assess the prevalence of cognitive impairment suspected of dementia among the Polish elderly and the relationships between cognitive performance and age, gender, place of residence and educational status. The presented data was the result of nationwide, multicentre PolSenior Study conducted from 2007 to 2011 in the Polish elderly population. Cognitive functions were evaluated using Mini-Mental State Examination (MMSE) performed by pre-trained nurses. The result of MMSE lower than 24 points was classified as cognitive impairment suspected of dementia and divided according to its severity into three stages: mild, moderate and severe dementia. The results were analysed in two ways: raw MMSE and MMSE scores after Mungas adjustment (MMSEadj), that is, corrected for age and educational level, and these were compared. To verify the suspicion of dementia an assessment was complemented by an interview of carers for the occurrence and course of memory disorders, treatment of dementia and by functional status assessment. In order to assess the prevalence of suspicion of dementia in the general Polish population, statistical analyses based on weighting were done. The suspicion of dementia on the basis of raw MMSE was made in 20.4% of respondents aged 65years and more, and after Mungas adjustment in 12.1% of older subjects. The prevalence of cognitive impairment grew with increasing age, as well as depending on the educational status of elderly respondents in both types of analyses; raw MMSE and MMSEadj. There was no significant difference in the prevalence of cognitive impairment according to gender in the general population (raw MMSE); however in analyses including MMSEadj results, the suspicion of dementia was made more often among men. Suspicion of dementia based on raw MMSE and MMSEadj results was made significantly more often among men than women at the age of 65-69years, and significantly more often among the oldest women, aged 90years and more. Suspicion of dementia was diagnosed more often in respondents living in rural communities (based on raw MMSE, but not on MMSEadj), which might be related to the differences in their educational status.

Socioeconomic status and survival among older adults with dementia and depression

BACKGROUND

People from lower socioeconomic groups have a higher risk of mortality. The impact of low socioeconomic status on survival among older adults with dementia and depression remains unclear.

AIMS

To investigate the association between socioeconomic status and mortality in people with dementia and late-life depression in China.

METHOD

Using Geriatric Mental Status - Automated Geriatric Examination for Computer Assisted Taxonomy (GMS-AGECAT) we interviewed 2978 people aged ⩾60 years in Anhui, China. We characterised baseline socioeconomic status and risk factors and diagnosed 223 people with dementia and 128 with depression. All-cause mortality was followed up over 5.6 years.

RESULTS

Individuals with dementia living in rural areas had a three times greater risk of mortality (multivariate adjusted hazard ratio (HR) = 2.96, 95% CI 1.45-6.04) than those in urban areas, and for those with depression the HR was 4.15 (95% CI 1.59-10.83). There were similar mortality rates when comparing people with dementia with low v. high levels of education, occupation and income, but individuals with depression with low v. high levels had non-significant increases in mortality of 11%, 50% and 55% respectively

CONCLUSIONS

Older adults with dementia and depression living in rural China had a significantly higher risk of mortality than urban counterparts. Interventions should be implemented in rural areas to tackle survival inequality in dementia and depression.

Dementia studies in Chinese populations

Variations in the prevalence of dementia in different ethnic groups have been reported worldwide, and a number of reviews have provided a picture of epidemiological studies in dementia research. However, little is known about epidemiological studies in Chinese populations. In this review, we searched PubMed and the Web of Science for original research articles published in English up to July 2013 on the prevalence, incidence, risk factors, and prognosis of dementia in Chinese populations worldwide. Except for the prevalence, we included only population-based follow-up studies. We identified 25 studies in elderly Chinese residents in Mainland China, Hong Kong, Taiwan, and Singapore, and found a higher prevalence of dementia in Mainland China than in the other locations, which may be due to that the studies from Mainland China are more recent than those from other locations. A notable increase in incidence was observed when dementia cases were diagnosed using 10/66 diagnostic criteria compared to other criteria. Studies on risk factors for dementia were limited and mostly from Mainland China. Age, gender, education, smoking, and alcohol consumption were related to the risk of dementia in Chinese populations. Only two prognostic studies were identified, and age, gender, and residential area were related to the prognosis of dementia. In conclusion, the prevalence, incidence, and risk factors for dementia found in Chinese populations were comparable to other ethnic groups, but no conclusive results on prognosis were found. The differences in prevalence and incidence were influenced by the diagnostic criteria and the time of study. Longitudinal population-based studies on the incidence, risk factors, and prognosis of dementia in Chinese populations are required.

Education is associated with lower levels of abdominal obesity in women with a non-agricultural occupation: an interaction study using China's Four Provinces survey

Background

The prevalence of obesity is increasing rapidly in low- and middle-income countries (LMICs) as their populations become exposed to obesogenic environments. The transition from an agrarian to an industrial and service-based economy results in important lifestyle changes. Yet different socioeconomic groups may experience and respond to these changes differently. Investigating the socioeconomic distribution of obesity in LMICs is key to understanding the causes of obesity but the field is limited by the scarcity of data and a uni-dimensional approach to socioeconomic status (SES). This study splits socioeconomic status into two dimensions to investigate how educated women may have lower levels of obesity in a context where labour market opportunities have shifted away from agriculture to other forms of employment.

Methods

The Four Provinces Study in China 2008/09 is a household-based community survey of 4,314 people aged ≥60  years (2,465 women). It was used to investigate an interaction between education (none/any) and occupation (agricultural/non-agricultural) on high-risk central obesity defined as a waist circumference ≥80 cm. An interaction term between education and occupation was incorporated in a multivariate logistic regression model, and the estimates adjusted for age, parity, urban/rural residence and health behaviours (smoking, alcohol, meat and fruit & vegetable consumption). Complete case analyses were undertaken and results confirmed using multiple imputation to impute missing data.

Results

An interaction between occupation and education was present (P = 0.02). In the group with no education, the odds of central obesity in the sedentary occupation group were more than double those of the agricultural occupation group even after taking age group and parity into account (OR; 95%CI: 2.21; 1.52, 3.21), while in the group with any education there was no evidence of such a relationship (OR; 95%CI: 1.25; 0.92, 1.70). Health behaviours appeared to account for some of the association.

Conclusion

These findings suggest that education may have a protective role in women against the higher odds of obesity associated with occupational shifts in middle-income countries, and that investment in women’s education may present an important long term investment in obesity prevention. Further research could elucidate the mechanisms behind this association.

Prevalence studies of dementia in mainland china, Hong Kong and taiwan: a systematic review and meta-analysis

BACKGROUND

Many studies have considered the prevalence of dementia in mainland China, Hong Kong and Taiwan. However, area level estimates have not been produced. This study examines area differences across mainland China, Hong Kong and Taiwan adjusting for the effect of methodological factors with the aim of producing estimates of the numbers of people with dementia in these areas.

METHOD AND FINDINGS

A search of Chinese and English databases identified 76 dementia prevalence studies based on samples drawn from mainland China, Hong Kong and Taiwan between 1980 and 2012. A pattern of significantly decreasing prevalence was observed from northern, central, southern areas of mainland China, Hong Kong and Taiwan. Area variations in dementia prevalence were not explained by differences in methodological factors (diagnostic criteria, age range, study sample size and sampling method), socioeconomic level or life expectancy between areas. The results of meta-analysis were applied to current population data to provide best estimate. Based on the DSM-IV diagnostic criteria, the total number of people aged 60 and over with dementia in mainland China, Hong Kong and Taiwan is 8.4 million (4.6%, 95% CI: 3.4, 5.8) and in northern, central and southern areas are 3.8 (5.1%, 95% CI: 4.1, 6.1), 3.2 (4.4%, 95% CI: 3.2, 5.6) and 1.2 (3.9%, 95% CI: 2.3, 5.4) million respectively. These estimates were mainly based on the studies existing in highly developed areas and potentially affected by incomplete and insufficient data.

CONCLUSIONS

The findings of this review provide a robust estimate of area differences in dementia prevalence. Application of the estimated prevalence to population data reveals the number of people with dementia is expected to double every 20 years, areas in mainland China will be facing the greatest dementia challenge.

Predictors of diabetes in older people in urban China

BACKGROUND

China has the largest number of people with diabetes in the world. Over the last 30 years China has experienced rapid economic growth and a growing income gap between rich and poor. The population is ageing, however diabetes in older people has not been well studied to date. In this study we determined incidence and predictors of diabetes in older Chinese people.

METHODS

During 2001, using a standard interview method, we examined 1,317 adults aged ≥65 years who did not have diabetes in the city of Hefei, and characterized baseline risk factors. Over 7.5 years of follow up, we documented incident diabetes using self-reported doctor diagnosis and the cause of death in the whole cohort, and HbA(1C) ≥48 mmol/mol in a nested case-control sample. A multivariate Cox regression model was employed to investigate risk of diabetes in relation to baseline risk factors.

RESULTS

During follow up, 119 persons had newly diagnosed diabetes. World age-standardised incidence of diabetes was 24.5 (95% CI 19.5-29.5) per 1,000 person-years. Risk of diabetes was significantly and positively associated with income, waist circumference and body mass index, smoking and uncontrolled hypertension, but negatively associated with having a hobby of walking and frequency of visiting children/other relatives and contacting neighbours/friends. Higher income was significantly associated with increased diabetes risk regardless of cardiovascular and psychosocial risk factors. Compared to those with middle income and no psychosocial risk factors, the hazard ratio for incident diabetes among participants with high income and psychosocial risk was 2.13 (95% CI 1.02-4.45).

CONCLUSIONS

Increasing incidence of diabetes in relation to high income has become an important public health issue in China. Maintaining social networks and gentle physical activities and reducing psychosocial factors may be integrated into current multi-faceted preventive strategies for curbing the epidemic of diabetes in the older population.

Association between environmental tobacco smoke exposure and dementia syndromes

OBJECTIVES

Environmental tobacco smoke (ETS) has a range of adverse health effects, but its association with dementia remains unclear and with dementia syndromes unknown. We examined the dose-response relationship between ETS exposure and dementia syndromes.

METHODS

Using a standard method of GMS, we interviewed 5921 people aged ≥60 years in five provinces in China in 2007-2009 and characterised their ETS exposure. Five levels of dementia syndrome were diagnosed using the Automated Geriatric Examination for Computer Assisted Taxonomy instrument. The relative risk (RR) of moderate (levels 1-2) and severe (levels 3-5) dementia syndromes among participants exposed to ETS was calculated in multivariate adjusted regression models.

RESULTS

626 participants (10.6%) had severe dementia syndromes and 869 (14.7%) moderate syndromes. Participants exposed to ETS had a significantly increased risk of severe syndromes (adjusted RR 1.29, 95% CI 1.05 to 1.59). This was dose-dependently related to exposure level and duration. The cumulative exposure dose data showed an adjusted RR of 0.99 (95% CI 0.76 to 1.28) for >0-24 level years of exposure, 1.15 (95% CI 0.93 to 1.42) for 25-49 level years, 1.18 (95% CI 0.87 to 1.59) for 59-74 level years, 1.39 (95% CI 1.03 to 1.84) for 75-99 level years and 1.95 (95% CI 1.34 to 2.83) for ≥100 level years. Significant associations with severe syndromes were found in never smokers and in former/current smokers. There were no positive associations between ETS and moderate dementia syndromes.

CONCLUSIONS

ETS should be considered an important risk factor for severe dementia syndromes. Avoidance of ETS may reduce the rates of severe dementia syndromes worldwide.

Interaction between education and household wealth on the risk of obesity in women in Egypt

BACKGROUND

Obesity is a growing problem in lower income countries particularly among women. There are few studies exploring individual socioeconomic status indicators in depth. This study examines the interaction of education and wealth in relation to obesity, hypothesising that education protects against the obesogenic effect of wealth.

METHODS

Four datasets of women of reproductive age from the Egyptian Demographic and Health Surveys spanning the period 1992-2008 are used to examine two distinct time periods: 1992/95 (N = 11097) and 2005/08 (N = 23178). The association in the two time periods between education level and household wealth in relation to the odds of being obese is examined, and the interaction between the two socioeconomic indicators investigated. Estimates are adjusted for age group and area of residence.

RESULTS

An interaction was found between the association of education and wealth with obesity in both time periods (P-value for interaction <0.001). For women with the lowest education level, moving up one wealth quintile was associated with a 78% increase in the odds of obesity in 1992/95 (OR; 95%CI: 1.78; 1.65,1.91) and a 33% increase in 2005/08 (OR; 95%CI: 1.33; 1.26,1.39). For women with the highest level of education, there was little evidence of an association between wealth and obesity (OR; 95%CI: 0.82; 0.57,1.16 in 1992/95 and 0.95; 0.84,1.08 in 2005/08). Obesity levels increased most in women who were in the no/primary education, poorest wealth quintile and rural groups (absolute difference in prevalence percentage points between the two time periods: 20.2, 20.1, and 21.3 respectively).

CONCLUSION

In the present study, wealth appears to be a risk factor for obesity in women with lower education levels, while women with higher education are protected. The findings also suggest that a reversal in the social distribution of obesity risk is occurring which can be explained by the large increase in obesity levels in lower socioeconomic groups between the two time periods.

Incident dementia in a defined older Chinese population

Background

Current knowledge about incident dementia is mainly derived from studies undertaken in the West, showing that dementia is related to older age, low socio-economic status, lack of social network, depression and cardiovascular disease risk factors. We know little about incidence and predictors of dementia in China, where the prevalence is increasing and the patterns of risk factors are different.

Methods

Using a standard interview method, we examined 1526 non-demented people aged ≥65 years who had at least minimal educational level in China in a 7.5-year follow up. Incident dementia was diagnosed by GMS-AGECAT algorithms and psychiatrists.

Results

Age-standardised incidence of dementia was 14.7 per 1000 person-years (95%CI 11.3–18.2 per 1000 person-years). The increased risk was significantly associated with age, female gender (adjusted odds ratio 2.48, 95%CI 1.20–5.13), low educational levels, smoking, angina (2.58, 1.01–6.59) and living with fewer family members. Among participants with low educational level, the increased risk was associated with higher income, and with the highest and lowest occupational classes; adjusted odds ratio 2.74 (95%CI 1.12–6.70) for officers/teachers, 3.11 (1.61–6.01) for manual labourers/peasants.

Conclusions

Our findings of high incidence of dementia and increased risk among people having low education levels but high income suggest a more potential epidemic and burden of dementia populations in China. Maintaining social network and activities and reducing cardiovascular factors in late life could be integrated into current multi-faceted preventive strategies for curbing the epidemic of dementia.