Ana Luisa Sosa

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

Summary 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. Funding Wellcome Trust (UK); WHO; the US Alzheimers Association; and Fondo Nacional De Ciencia Y Tecnologia, Consejo De Desarrollo Cientifico Y Humanistico, and Universidad Central De Venezuela (Venezuela).

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

Summary 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 Alzheimers Association; Fondo Nacional de Ciencia Y Tecnologia, Consejo de Desarrollo Cientifico Y Humanistico, Universidad Central de Venezuela.

The protocols for the 10/66 dementia research group population-based research programme

BackgroundLatin America, China and India are experiencing unprecedentedly rapid demographic ageing with an increasing number of people with dementia. The 10/66 Dementia Research Groups title refers to the 66% of people with dementia that live in developing countries and the less than one tenth of population-based research carried out in those settings. This paper describes the protocols for the 10/66 population-based and intervention studies that aim to redress this imbalance.Methods/designCross-sectional comprehensive one phase surveys have been conducted of all residents aged 65 and over of geographically defined catchment areas in ten low and middle income countries (India, China, Nigeria, Cuba, Dominican Republic, Brazil, Venezuela, Mexico, Peru and Argentina), with a sample size of between 1000 and 3000 (generally 2000). Each of the studies uses the same core minimum data set with cross-culturally validated assessments (dementia diagnosis and subtypes, mental disorders, physical health, anthropometry, demographics, extensive non communicable disease risk factor questionnaires, disability/functioning, health service utilisation, care arrangements and caregiver strain). Nested within the population based studies is a randomised controlled trial of a caregiver intervention for people with dementia and their families (ISRCTN41039907; ISRCTN41062011; ISRCTN95135433; ISRCTN66355402; ISRCTN93378627; ISRCTN94921815). A follow up of 2.5 to 3.5 years will be conducted in 7 countries (China, Cuba, Dominican Republic, Venezuela, Mexico, Peru and Argentina) to assess risk factors for incident dementia, stroke and all cause and cause-specific mortality; verbal autopsy will be used to identify causes of death.DiscussionThe 10/66 DRG baseline population-based studies are nearly complete. The incidence phase will be completed in 2009. All investigators are committed to establish an anonymised file sharing archive with monitored public access. Our aim is to create an evidence base to empower advocacy, raise awareness about dementia, and ensure that the health and social care needs of older people are anticipated and met.

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

Summary 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 Alzheimers Association, FONACIT/ CDCH/ UCV

Prevalence of stroke and related burden among older people living in Latin America, India and China

Objectives Despite the growing importance of stroke in developing countries, little is known of stroke burden in survivors. The authors investigated the prevalence of self-reported stroke, stroke-related disability, dependence and care-giver strain in Latin America (LA), China and India. Methods Cross-sectional surveys were conducted on individuals aged 65+ (n=15 022) living in specified catchment areas. Self-reported stroke diagnosis, disability, care needs and care giver burden were assessed using a standardised protocol. For those reporting stroke, the correlates of disability, dependence and care-giver burden were estimated at each site using Poisson or linear regression, and combined meta-analytically. Results The prevalence of self-reported stroke ranged between 6% and 9% across most LA sites and urban China, but was much lower in urban India (1.9%), and in rural sites in India (1.1%), China (1.6%) and Peru (2.7%). The proportion of stroke survivors needing care varied between 20% and 39% in LA sites but was higher in rural China (44%), urban China (54%) and rural India (73%). Comorbid dementia and depression were the main correlates of disability and dependence. Conclusion The prevalence of stroke in urban LA and Chinese sites is nearly as high as in industrialised countries. High levels of disability and dependence in the other mainly rural and less-developed sites suggest underascertainment of less severe cases as one likely explanation for the lower prevalence in those settings. As the health transition proceeds, a further increase in numbers of older stroke survivors is to be anticipated. In addition to prevention, stroke rehabilitation and long-term care needs should be addressed.

Prevalence, Distribution, and Impact of Mild Cognitive Impairment in Latin America, China, and India: A 10/66 Population-Based Study

A set of cross-sectional surveys carried out in Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India reveal the prevalence and between-country variation in mild cognitive impairment at a population level.

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.

The 10/66 Dementia Research Group's fully operationalised DSM-IV dementia computerized diagnostic algorithm, compared with the 10/66 dementia algorithm and a clinician diagnosis: a population validation study

BackgroundThe criterion for dementia implicit in DSM-IV is widely used in research but not fully operationalised. The 10/66 Dementia Research Group sought to do this using assessments from their one phase dementia diagnostic research interview, and to validate the resulting algorithm in a population-based study in Cuba.MethodsThe criterion was operationalised as a computerised algorithm, applying clinical principles, based upon the 10/66 cognitive tests, clinical interview and informant reports; the Community Screening Instrument for Dementia, the CERAD 10 word list learning and animal naming tests, the Geriatric Mental State, and the History and Aetiology Schedule – Dementia Diagnosis and Subtype. This was validated in Cuba against a local clinician DSM-IV diagnosis and the 10/66 dementia diagnosis (originally calibrated probabilistically against clinician DSM-IV diagnoses in the 10/66 pilot study).ResultsThe DSM-IV sub-criteria were plausibly distributed among clinically diagnosed dementia cases and controls. The clinician diagnoses agreed better with 10/66 dementia diagnosis than with the more conservative computerized DSM-IV algorithm. The DSM-IV algorithm was particularly likely to miss less severe dementia cases. Those with a 10/66 dementia diagnosis who did not meet the DSM-IV criterion were less cognitively and functionally impaired compared with the DSMIV confirmed cases, but still grossly impaired compared with those free of dementia.ConclusionThe DSM-IV criterion, strictly applied, defines a narrow category of unambiguous dementia characterized by marked impairment. It may be specific but incompletely sensitive to clinically relevant cases. The 10/66 dementia diagnosis defines a broader category that may be more sensitive, identifying genuine cases beyond those defined by our DSM-IV algorithm, with relevance to the estimation of the population burden of this disorder.

Dietary fish and meat intake and dementia in Latin America, China, and India: a 10/66 Dementia Research Group population-based study

Background: Evidence of an association between fish and meat consumption and risk of dementia is inconsistent and nonexistent in populations in developing countries. Objective: The objective was to investigate associations between fish and meat consumption with dementia in low- and middle-income countries. Design: One-phase cross-sectional surveys were conducted in all residents aged ≥65 y in 11 catchment areas in China, India, Cuba, the Dominican Republic, Venezuela, Mexico, and Peru. A total of 14,960 residents were assessed by using the 10/66 standardized protocol, which includes face-to-face interviews for dietary habits and a cross-culturally validated dementia diagnosis. Results: Dietary intakes and the prevalence of dementia varied between sites. We combined site-specific Poisson regression prevalence ratios (PRs) for the association between fish and meat consumption and dementia in 2 fixed-effect model meta-analyses adjusted for sociodemographic and health characteristics and fish and meat consumption as appropriate. We found a dose-dependent inverse association between fish consumption and dementia (PR: 0.81; 95% CI: 0.72, 0.91) that was consistent across all sites except India and a less-consistent, dose-dependent, direct association between meat consumption and prevalence of dementia (PR: 1.19; 95% CI: 1.07, 1.31). Conclusions: Our results extend findings on the associations of fish and meat consumption with dementia risk to populations in low- and middle-income countries and are consistent with mechanistic data on the neuroprotective actions of omega-3 (n–3) long-chain polyunsaturated fatty acids commonly found in fish. The inverse association between fish and prevalent dementia is unlikely to result from poorer dietary habits among demented individuals (reverse causality) because meat consumption was higher in those with a diagnosis of dementia.

Hypertension prevalence, awareness, treatment and control among older people in Latin America, India and China: a 10/66 cross-sectional population-based survey.

Objectives To estimate the prevalence, social patterning, treatment and control of hypertension among older people in the 10/66 Dementia Research Group developing country sites. Methods Cross-sectional surveys of SBP, hypertension, and hypertension awareness, treatment and control among 17 014 people aged 65 years and over in eight urban and four rural sites in Latin America, India and China. Results Hypertension prevalence was higher in urban (range 52.6–79.8%) than rural sites (range 42.6–56.9%), and lower in men than women [pooled prevalence ratio 0.89, 95% confidence interval (CI) 0.85–0.93]. Educational attainment was positively associated with hypertension in rural and least-developed sites. Age-standardized morbidity ratios, compared to USA (100), were higher in urban sites in Cuba (105), Dominican Republic (109), and Venezuela (107), similar in Puerto Rico (105), urban Mexico (99) and urban India (101), and lower in urban (75) and rural (61) Peru, rural Mexico (81), urban (91) and rural (84) China and rural India (65). In most Latin American centres, and urban China just over one-third of those with hypertension were controlled (BP < 140/90). Control was poor in rural China (2%), urban India (12%) and rural India (9%). The proportion controlled, not compositional factors (age, sex, education and obesity), explained most of the between-site variation in SBP. Conclusion Uncontrolled hypertension is common among older people in developing countries, and may rise further during the demographic and health transitions. It is a major determinant of population SBP level. Strengthening primary care to improve hypertension management is necessary for primary prevention.