Socioeconomic differences in handgrip strength and its association with measures of intrinsic capacity among older adults in six middle-income countries

Handgrip strength, a measure of muscular strength is a powerful predictor of declines in intrinsic capacity, functional abilities, the onset of morbidity and mortality among older adults. This study documents socioeconomic (SES) differences in handgrip strength among older adults aged 50 years and over in six middle-income countries and investigates the association of handgrip strength with measures of intrinsic capacity-a composite of all the physical and mental capacities of an individual. Secondary data analysis of cross-sectional population-based data from six countries from the WHO's Study on global AGEing and adult health (SAGE) Wave 1 were conducted. Three-level linear hierarchical models examine the association of demographic, socioeconomic status and multimorbidity variables with handgrip strength. Regression-based Relative Index of Inequality (RII) examines socioeconomic inequalities in handgrip strength; and multilevel linear and logistic hierarchical regression models document the association between handgrip strength and five domains of intrinsic capacity: locomotion, psychological, cognitive capacity, vitality and sensory. Wealth quintiles are positively associated with handgrip strength among men across all countries except South Africa while the differences by education were notable for China and India. Work and nutritional status are positively associated with handgrip strength. Our findings provide new evidence of robust association between handgrip strength and other measures of intrinsic capacity and confirms that handgrip strength is a single most important measure of capacity among older persons.

The association between, depression, anxiety, and mortality in older people across eight low- and middle-income countries: Results from the 10/66 cohort study

OBJECTIVES

Depression and anxiety are common mental disorders in later life. Few population-based studies have investigated their potential impacts on mortality in low- and middle-income countries (LMICs). The aim of this study is to examine the associations between depression, anxiety, their comorbidity, and mortality in later life using a population-based cohort study across eight LMICs.

METHODS

This analysis was based on the 10/66 cohort study including 15 991 people aged 65 years or above in Cuba, Dominican Republic, Venezuela, Mexico, Peru, Puerto Rico, China, and India, with an average follow-up time of 3.9 years. Subthreshold and clinical levels of depression were determined using EURO-D and ICD-10 criteria, and anxiety was based on Geriatric Mental State (GMS)-Automated Geriatric Examination for Computer Assisted Taxonomy (AGECAT). Cox proportional hazard modelling was used to estimate how having depression, anxiety, or both was associated with mortality adjusting for sociodemographic and health factors.

RESULTS

Participants with clinical depression (hazard ratio [HR]: 1.45; 95% CI, 1.24-1.70) and subthreshold anxiety (HR: 1.26; 95% CI, 1.15-1.38) had higher risk of mortality than those without the conditions after adjusting for sociodemographic factors and health conditions. Comorbidity of depression and anxiety was associated with a 30% increased risk of mortality but the effect sizes varied across countries (Higgins I2  = 58.8%), with the strongest association in India (HR: 1.99; 95% CI, 1.21-3.27).

CONCLUSIONS

Depression and anxiety appear to be associated with mortality in older people living in LMICs. Variation in effect sizes may indicate different barriers to health service access across countries. Future studies may investigate underlying mechanisms and identify potential interventions to reduce the impact of common mental disorders.

The structure and predictive value of intrinsic capacity in a longitudinal study of ageing

OBJECTIVES

To assess the validity of the WHO concept of intrinsic capacity in a longitudinal study of ageing; to identify whether this overall measure disaggregated into biologically plausible and clinically useful subdomains; and to assess whether total capacity predicted subsequent care dependence.

DESIGN

Structural equation modelling of biomarkers and self-reported measures in the English Longitudinal Study of Ageing including exploratory factor analysis, exploratory bi-factor analysis and confirmatory factor analysis. Longitudinal mediation and moderation analysis of incident care dependence.

SETTINGS

Community, United Kingdom.

PARTICIPANTS

2560 eligible participants aged over 60 years.

MAIN OUTCOME MEASURES

Activities of daily living (ADL) and instrumental activities of daily living (IADL).

RESULTS

One general factor (intrinsic capacity) and five subfactors emerged: locomotor, cognitive; psychological; sensory; and 'vitality'. This structure is consistent with biological theory and the model had a good fit for the data (χ²=71.2 (df=39)). The summary score of intrinsic capacity and specific subfactors showed good construct validity. In a causal path model examining incident loss of ADL and IADL, intrinsic capacity had a direct relationship with the outcome-root mean square error of approximation (RMSEA)=0.02 (90% CI 0.001 to 0.05) and RMSEA=0.008 (90% CI0.001 to 0.03) respectively-and was a strong mediator for the effect of age, sex, wealth and education. Multimorbidity had an independent direct relationship with incident loss of ADLs but not IADLs, and also operated through intrinsic capacity. More of the indirect effect of personal characteristics on incident loss of ADLs and IADLs was mediated by intrinsic capacity than multimorbidity.

CONCLUSIONS

The WHO construct of intrinsic capacity appears to provide valuable predictive information on an individual's subsequent functioning, even after accounting for the number of multimorbidities. The proposed general factor and subdomain structure may contribute to a transformative paradigm for future research and clinical practice.

Dependence- and Disability-Free Life Expectancy Across Eight Low- and Middle-Income Countries: A 10/66 Study

Objective: The objective of this study was to estimate healthy life expectancies in eight low- and middle-income countries (LMICs), using two indicators: disability-free life expectancy (DFLE) and dependence-free life expectancy (DepFLE). Method: Using the Sullivan method, healthy life expectancy was calculated based on the prevalence of dependence and disability from the 10/66 cohort study, which included 16,990 people aged 65 or above in China, Cuba, Dominican Republic, India, Mexico, Peru, Puerto Rico, and Venezuela, and country-specific life tables from the World Population Prospects 2017. Results: DFLE and DepFLE declined with older age across all sites and were higher in women than men. Mexico reported the highest DFLE at age 65 for men (15.4, SE = 0.5) and women (16.5, SE = 0.4), whereas India had the lowest with (11.5, SE = 0.3) in men and women (11.7, SE = 0.4). Discussion: Healthy life expectancy based on disability and dependency can be a critical indicator for aging research and policy planning in LMICs.

The magnitude of and health system responses to the mental health treatment gap in adults in India and China

This Series paper describes the first systematic effort to review the unmet mental health needs of adults in China and India. The evidence shows that contact coverage for the most common mental and substance use disorders is very low. Effective coverage is even lower, even for severe disorders such as psychotic disorders and epilepsy. There are vast variations across the regions of both countries, with the highest treatment gaps in rural regions because of inequities in the distribution of mental health resources, and variable implementation of mental health policies across states and provinces. Human and financial resources for mental health are grossly inadequate with less than 1% of the national health-care budget allocated to mental health in either country. Although China and India have both shown renewed commitment through national programmes for community-oriented mental health care, progress in achieving coverage is far more substantial in China. Improvement of coverage will need to address both supply-side barriers and demand-side barriers related to stigma and varying explanatory models of mental disorders. Sharing tasks with community-based workers in a collaborative stepped-care framework is an approach that is ripe to be scaled up, in particular through integration within national priority health programmes. India and China need to invest in increasing demand for services through active engagement with the community, to strengthen service user leadership and ensure that the content and delivery of mental health programmes are culturally and contextually appropriate.

Psychological well-being of parents and family caregivers of children with hearing impairment in south India: influence of behavioural problems in children and social support

Parents of children with hearing impairment are at increased risk of mental health morbidities. We examined the predictive factors associated with caregiver's strain and psychological morbidities in parents and family caregivers of children with hearing impairment. In total, n = 201 parents and family caregivers of children with and without hearing impairment aged 3 to 16 years were recruited. Caregiver's strain and psychological morbidities were measured using the Zarit Burden scale and the World Health Organization's Self-Reporting Questionnaire (SRQ-20). Presence of behavioural problems in children was measured using the Strengths and Difficulties Questionnaire. After adjustment, low educational attainment and domestic violence were found to be associated with caregiving strain, whereas dissatisfaction with social support from family, behavioural problems in children, and domestic violence strongly predicted psychological morbidities. Addressing the mental healthcare needs of parents may help in downsizing the impact of psychological morbidities on the well-being of children with hearing impairment.

Is hypertension associated with job strain? A meta-analysis of observational studies

Job strain results from a combination of high workload and few decision-making opportunities in the workplace. There is inconsistent evidence regarding the association between job strain and hypertension, and methodological shortcomings preclude firm conclusions. Thus, a meta-analysis of observational studies on hypertension among occupational groups was conducted to determine whether job strain was associated with hypertension. In January 2012, we carried out a comprehensive, topic-specific electronic literature search of the Ovid MEDLINE, EMBASE and PsychoINFO databases complemented by individual help from non-communicable disease experts. Experimental/interventional studies and studies on personality disorders were excluded. Nine of 894 identified studies met the eligibility criteria and were included in the meta-analysis. The pooled OR of the nine studies was 1.3 (95% CI 1.14 to 1.48; p<0.001), of case-control studies 3.17 (95% CI 1.79 to 5.60; p<0.001) and of cohort studies 1.24 (95% CI 1.09 to 1.41; p<0.001), all of which indicated statistically significant positive associations between job strain and hypertension. In a subgroup analysis, cohort studies of good methodological quality showed significant associations between job strain and hypertension, while those of poor methodological quality showed no association or subgroup differences. We conclude that despite methodological differences, case-control and cohort studies of good methodological quality showed positive associations between hypertension and job strain.

Is hypertension associated with job strain? A meta-analysis of observational studies

Job strain results from a combination of high workload and few decision-making opportunities in the workplace. There is inconsistent evidence regarding the association between job strain and hypertension, and methodological shortcomings preclude firm conclusions. Thus, a meta-analysis of observational studies on hypertension among occupational groups was conducted to determine whether job strain was associated with hypertension. In January 2012, we carried out a comprehensive, topic-specific electronic literature search of the Ovid MEDLINE, EMBASE and PsychoINFO databases complemented by individual help from non-communicable disease experts. Experimental/interventional studies and studies on personality disorders were excluded. Nine of 894 identified studies met the eligibility criteria and were included in the meta-analysis. The pooled OR of the nine studies was 1.29 (95% CI 1.14 to 1.47; p<0.001), of case–control studies 2.88 (95% CI 1.63 to 5.09; p<0.001) and of cohort studies 1.24 (95% CI1.09 to 1.41; p<0.001), all of which indicated statistically significant positive associations between job strain and hypertension [corrected]. In a subgroup analysis, cohort studies of good methodological quality showed significant associations between job strain and hypertension, while those of poor methodological quality showed no association or subgroup differences. We conclude that despite methodological differences, case-control and cohort studies of good methodological quality showed positive associations between hypertension and job strain.

Dementia incidence and mortality in middle-income countries, and associations with indicators of cognitive reserve: a 10/66 Dementia Research Group population-based cohort study

BACKGROUND

Results of the few cohort studies from countries with low incomes or middle incomes suggest a lower incidence of dementia than in high-income countries. We assessed incidence of dementia according to criteria from the 10/66 Dementia Research Group and Diagnostic and Statistical Manual of Mental Disorders (DSM) IV, the effect of dementia at baseline on mortality, and the independent effects of age, sex, socioeconomic position, and indicators of cognitive reserve.

METHODS

We did a population-based cohort study of all people aged 65 years and older living in urban sites in Cuba, the Dominican Republic, and Venezuela, and rural and urban sites in Peru, Mexico, and China, with ascertainment of incident 10/66 and DSM-IV dementia 3-5 years after cohort inception. We used questionnaires to obtain information about age in years, sex, educational level, literacy, occupational attainment, and number of household assets. We obtained information about mortality from all sites. For participants who had died, we interviewed a friend or relative to ascertain the likelihood that they had dementia before death.

FINDINGS

12,887 participants were interviewed at baseline. 11,718 were free of dementia, of whom 8137 (69%) were reinterviewed, contributing 34,718 person-years of follow-up. Incidence for 10/66 dementia varied between 18·2 and 30·4 per 1000 person-years, and were 1·4-2·7 times higher than were those for DSM-IV dementia (9·9-15·7 per 1000 person-years). Mortality hazards were 1·56-5·69 times higher in individuals with dementia at baseline than in those who were dementia-free. Informant reports suggested a high incidence of dementia before death; overall incidence might be 4-19% higher if these data were included. 10/66 dementia incidence was independently associated with increased age (HR 1·67; 95% CI 1·56-1·79), female sex (0·72; 0·61-0·84), and low education (0·89; 0·81-0·97), but not with occupational attainment (1·04; 0·95-1·13).

INTERPRETATION

Our results provide supportive evidence for the cognitive reserve hypothesis, showing that in middle-income countries as in high-income countries, education, literacy, verbal fluency, and motor sequencing confer substantial protection against the onset of dementia.

FUNDING

Wellcome Trust Health Consequences of Population Change Programme, WHO, US Alzheimer's Association, FONACIT/ CDCH/ UCV.

Strain and its correlates among carers of people with dementia in low-income and middle-income countries. A 10/66 Dementia Research Group population-based survey

OBJECTIVES

In a multi-site population-based study in several middle-income countries, we aimed to investigate relative contributions of care arrangements and characteristics of carers and care recipients to strain among carers of people with dementia. Based on previous research, hypotheses focused on carer sex, care inputs, behavioural and psychological symptoms (BPSD) and socioeconomic status, together with potential buffering effects of informal support and employing paid carers.

METHODS

In population-based catchment area surveys in 11 sites in Latin America, India and China, we analysed data collected from people with dementia and care needs, and their carers. Carer strain was assessed with the Zarit Burden Interview.

RESULTS

With 673 care recipient/carer dyads interviewed (99% of those eligible), mean Zarit Burden Interview scores ranged between 17.1 and 27.9 by site. Women carers reported more strain than men. The most substantial correlates of carer strain were primary stressors BPSD, dementia severity, needs for care and time spent caring. Socioeconomic status was not associated with carer strain. Those cutting back on work experienced higher strain. There was tentative evidence for a protective effect of having additional informal or paid support.

CONCLUSIONS

Our findings underline the global impact of caring for a person with dementia and support the need for scaling up carer support, education and training. That giving up work to care was prevalent and associated with substantial increased strain emphasizes the economic impact of caring on the household. Carer benefits, disability benefits for people with dementia and respite care should all be considered.

Socioeconomic factors and all cause and cause-specific mortality among older people in Latin America, India, and China: a population-based cohort study

BACKGROUND

Even in low and middle income countries most deaths occur in older adults. In Europe, the effects of better education and home ownership upon mortality seem to persist into old age, but these effects may not generalise to LMICs. Reliable data on causes and determinants of mortality are lacking.

METHODS AND FINDINGS

The vital status of 12,373 people aged 65 y and over was determined 3-5 y after baseline survey in sites in Latin America, India, and China. We report crude and standardised mortality rates, standardized mortality ratios comparing mortality experience with that in the United States, and estimated associations with socioeconomic factors using Cox's proportional hazards regression. Cause-specific mortality fractions were estimated using the InterVA algorithm. Crude mortality rates varied from 27.3 to 70.0 per 1,000 person-years, a 3-fold variation persisting after standardisation for demographic and economic factors. Compared with the US, mortality was much higher in urban India and rural China, much lower in Peru, Venezuela, and urban Mexico, and similar in other sites. Mortality rates were higher among men, and increased with age. Adjusting for these effects, it was found that education, occupational attainment, assets, and pension receipt were all inversely associated with mortality, and food insecurity positively associated. Mutually adjusted, only education remained protective (pooled hazard ratio 0.93, 95% CI 0.89-0.98). Most deaths occurred at home, but, except in India, most individuals received medical attention during their final illness. Chronic diseases were the main causes of death, together with tuberculosis and liver disease, with stroke the leading cause in nearly all sites.

CONCLUSIONS

Education seems to have an important latent effect on mortality into late life. However, compositional differences in socioeconomic position do not explain differences in mortality between sites. Social protection for older people, and the effectiveness of health systems in preventing and treating chronic disease, may be as important as economic and human development.

Equity in the delivery of community healthcare to older people: findings from 10/66 Dementia Research Group cross-sectional surveys in Latin America, China, India and Nigeria

BACKGROUND

To describe patterns of recent health service utilisation, and consequent out-of-pocket expenses among older people in countries with low and middle incomes, and to assess the equity with which services are accessed and delivered.

METHODS

17,944 people aged 65 years and over were assessed in one-phase population-based cross-sectional surveys in geographically-defined catchment areas in nine countries - urban and rural sites in China, India, Mexico and Peru, urban sites in Cuba, Dominican Republic, Puerto Rico and Venezuela, and a rural site in Nigeria. The main outcome was use of community health care services in the past 3 months. Independent associations were estimated with indicators of need (dementia, depression, physical impairments), predisposing factors (age, sex, and education), and enabling factors (household assets, pension receipt and health insurance) using Poisson regression to generate prevalence ratios and fixed effects meta-analysis to combine them.

RESULTS

The proportion using healthcare services varied from 6% to 82% among sites. Number of physical impairments (pooled prevalence ratio 1.37, 95% CI 1.26-1.49) and ICD-10 depressive episode (pooled PR 1.21, 95% CI 1.07-1.38) were associated with service use, but dementia was inversely associated (pooled PR 0.93, 95% CI 0.90-0.97). Other correlates were female sex, higher education, more household assets, receiving a pension, and health insurance. Standardisation for age, sex, physical impairments, depression and dementia did not explain variation in service use. There was a strong borderline significant ecological correlation between the proportion of consultations requiring out-of-pocket costs and the prevalence of health service use (r = -0.50, p = 0.09).

CONCLUSIONS

While there was little evidence of ageism, inequity was apparent in the independent enabling effects of education and health insurance cover, the latter particularly in sites where out-of-pocket expenses were common, and private health insurance an important component of healthcare financing. Variation in service use among sites was most plausibly accounted for by stark differences in the extent of out-of-pocket expenses, and the ability of older people and their families to afford them. Health systems that finance medical services through out-of-pocket payments risk excluding the poorest older people, those without a secure regular income, and the uninsured.

The association between common physical impairments and dementia in low and middle income countries, and, among people with dementia, their association with cognitive function and disability. A 10/66 Dementia Research Group population-based study

OBJECTIVE

Chronic physical comorbidity is common in dementia. However, there is an absence of evidence to support good practice guidelines for attention to these problems. We aimed to study the extent of this comorbidity and its impact on cognitive function and disability in population-based studies in low and middle income countries, where chronic diseases and impairments are likely to be both common and undertreated.

METHODS

A multicentre cross-sectional survey of all over 65 year old residents (n = 15 022) in 11 catchment areas in China, India, Cuba, Dominican Republic, Venezuela, Mexico and Peru. We estimated the prevalence of pain, incontinence, hearing and visual impairments, mobility impairment and undernutrition according to the presence of dementia and its severity, and, among those with dementia, the independent contribution of these impairments to cognitive function and disability, adjusting for age, gender, education and dementia severity.

RESULTS

Incontinence, hearing impairment, mobility impairment and undernutrition were consistently linearly associated with the presence of dementia and its severity across regions. Among people with dementia, incontinence, hearing impairment and mobility impairment were independently associated with disability in all regions while the contributions of pain, visual impairment and undernutrition were inconsistent. Only hearing impairment made a notable independent contribution to cognitive impairment.

CONCLUSIONS

There is an urgent need for clinical trials of the feasibility, efficacy and cost-effectiveness of regular physical health checks and remediation of identified pathologies, given the considerable comorbidity identified in our population based studies, and the strong evidence for independent impact upon functioning.

Predictors of mortality among elderly people living in a south Indian urban community; a 10/66 Dementia Research Group prospective population-based cohort study

Background

Eighty percent of deaths occur in low and middle income countries (LMIC), where chronic diseases are the leading cause. Most of these deaths are of older people, but there is little information on the extent, pattern and predictors of their mortality. We studied these among people aged 65 years and over living in urban catchment areas in Chennai, south India.

Methods

In a prospective population cohort study, 1005 participants were followed-up after three years. Baseline assessment included sociodemographic and socioeconomic characteristics, health behaviours, physical, mental and cognitive disorders, disability and subjective global health.

Results

At follow-up, 257 (25.6%) were not traced. Baseline characteristics were similar to the 748 whose vital status was ascertained; 154 (20.6%) had died. The mortality rate was 92.5/1000 per annum for men and 51.0/1000 per annum for women. Adjusting for age and sex, mortality was associated with older age, male sex, having no friends, physical inactivity, smaller arm circumference, dementia, depression, poor self-rated health and disability. A parsimonious model included, in order of aetiologic force, male sex, smaller arm circumference, age, disability, and dementia. The total population attributable risk fraction was 0.90.

Conclusion

A balanced approach to prevention of chronic disease deaths requires some attention to proximal risk factors in older people. Smoking and obesity seem much less relevant than in younger people. Undernutrition is preventable. While dementia makes the largest contribution to disability and dependency, comorbidity is the rule, and more attention should be given to the chronic care needs of those affected, and their carers.

Measuring disability across cultures--the psychometric properties of the WHODAS II in older people from seven low- and middle-income countries. The 10/66 Dementia Research Group population-based survey

We evaluated the psychometric properties of the 12-item interviewer-administered screener version of the World Health Organization Disability Assessment Schedule-version II (WHODAS II) among older people living in seven low- and middle-income countries. Principal component analysis (PCA), confirmatory factor analysis (CFA) and Mokken analyses were carried out to test for unidimensionality, hierarchical structure, and measurement invariance across 10/66 Dementia Research Group sites. PCA generated a one-factor solution in most sites. In CFA, the two-factor solution generated in Dominican Republic fitted better for all sites other than rural China. The two factors were not easily interpretable, and may have been an artefact of differing item difficulties. Strong internal consistency and high factor loadings for the one-factor solution supported unidimensionality. Furthermore, the WHODAS II was found to be a 'strong' Mokken scale. Measurement invariance was supported by the similarity of factor loadings across sites, and by the high between-site correlations in item difficulties. The Mokken results strongly support that the WHODAS II 12-item screener is a unidimensional and hierarchical scale confirming to item response theory (IRT) principles, at least at the monotone homogeneity model level. More work is needed to assess the generalizability of our findings to different populations.

Contribution of chronic diseases to disability in elderly people in countries with low and middle incomes: a 10/66 Dementia Research Group population-based survey

BACKGROUND

Disability in elderly people in countries with low and middle incomes is little studied; according to Global Burden of Disease estimates, visual impairment is the leading contributor to years lived with disability in this population. We aimed to assess the contribution of physical, mental, and cognitive chronic diseases to disability, and the extent to which sociodemographic and health characteristics account for geographical variation in disability.

METHODS

We undertook cross-sectional surveys of residents aged older than 65 years (n=15 022) in 11 sites in seven countries with low and middle incomes (China, India, Cuba, Dominican Republic, Venezuela, Mexico, and Peru). Disability was assessed with the 12-item WHO disability assessment schedule 2.0. Dementia, depression, hypertension, and chronic obstructive pulmonary disease were ascertained by clinical assessment; diabetes, stroke, and heart disease by self-reported diagnosis; and sensory, gastrointestinal, skin, limb, and arthritic disorders by self-reported impairment. Independent contributions to disability scores were assessed by zero-inflated negative binomial regression and Poisson regression to generate population-attributable prevalence fractions (PAPF).

FINDINGS

In regions other than rural India and Venezuela, dementia made the largest contribution to disability (median PAPF 25.1% [IQR 19.2-43.6]). Other substantial contributors were stroke (11.4% [1.8-21.4]), limb impairment (10.5% [5.7-33.8]), arthritis (9.9% [3.2-34.8]), depression (8.3% [0.5-23.0]), eyesight problems (6.8% [1.7-17.6]), and gastrointestinal impairments (6.5% [0.3-23.1]). Associations with chronic diseases accounted for around two-thirds of prevalent disability. When zero inflation was taken into account, between-site differences in disability scores were largely attributable to compositional differences in health and sociodemographic characteristics.

INTERPRETATION

On the basis of empirical research, dementia, not blindness, is overwhelmingly the most important independent contributor to disability for elderly people in countries with low and middle incomes. Chronic diseases of the brain and mind deserve increased prioritisation. Besides disability, they lead to dependency and present stressful, complex, long-term challenges to carers. Societal costs are enormous.

FUNDING

Wellcome Trust; WHO; US Alzheimer's Association; Fondo Nacional de Ciencia Y Tecnologia, Consejo de Desarrollo Cientifico Y Humanistico, Universidad Central de Venezuela.

Prevalence of dementia in Latin America, India, and China: a population-based cross-sectional survey

BACKGROUND

Studies have suggested that the prevalence of dementia is lower in developing than in developed regions. We investigated the prevalence and severity of dementia in sites in low-income and middle-income countries according to two definitions of dementia diagnosis.

METHODS

We undertook one-phase cross-sectional surveys of all residents aged 65 years and older (n=14 960) in 11 sites in seven low-income and middle-income countries (China, India, Cuba, Dominican Republic, Venezuela, Mexico, and Peru). Dementia diagnosis was made according to the culturally and educationally sensitive 10/66 dementia diagnostic algorithm, which had been prevalidated in 25 Latin American, Asian, and African centres; and by computerised application of the dementia criterion from the Diagnostic and Statistical Manual of Mental Disorders (DSM IV). We also compared prevalence of DSM-IV dementia in each of the study sites with that from estimates in European studies.

FINDINGS

The prevalence of DSM-IV dementia varied widely, from 0.3% (95% CI 0.1-0.5) in rural India to 6.3% (5.0-7.7) in Cuba. After standardisation for age and sex, DSM-IV prevalence in urban Latin American sites was four-fifths of that in Europe (standardised morbidity ratio 80 [95% CI 70-91]), but in China the prevalence was only half (56 [32-91] in rural China), and in India and rural Latin America a quarter or less of the European prevalence (18 [5-34] in rural India). 10/66 dementia prevalence was higher than that of DSM-IV dementia, and more consistent across sites, varying between 5.6% (95% CI 4.2-7.0) in rural China and 11.7% (10.3-13.1) in the Dominican Republic. The validity of the 847 of 1345 cases of 10/66 dementia not confirmed by DSM-IV was supported by high levels of associated disability (mean WHO Disability Assessment Schedule II score 33.7 [SD 28.6]).

INTERPRETATION

As compared with the 10/66 dementia algorithm, the DSM-IV dementia criterion might underestimate dementia prevalence, especially in regions with low awareness of this emerging public-health problem.