SummaryBackgroundStudies 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.MethodsWe 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.FindingsThe 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]).InterpretationAs 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.FundingWellcome Trust (UK); WHO; the US Alzheimer's Association; and Fondo Nacional De Ciencia Y Tecnologia, Consejo De Desarrollo Cientifico Y Humanistico, and Universidad Central De Venezuela (Venezuela).

Background: 1) To report site-specific normative values by age, sex and educational level for four components of the 10/66 Dementia Research Group cognitive test battery; 2) to estimate the main and interactive effects of age, sex, and educational level by site; and 3) to investigate the effect of site by region and by rural or urban location.

The treatment gap poses a significant challenge for Latin American health systems, with their relatively weak primary care services and reliance on private specialists; local treatment trials could establish the cost-effectiveness of mental health investment in the government sector.

Cleusa Ferri and colleagues studied mortality rates in over 12,000 people aged 65 years and over in Latin America, India, and China and showed that chronic diseases are the main causes of death and that education has an important effect on mortality.

Among Maracaibo Aging Study participants younger than 65 years, the incidence of dementia was higher than that of US Whites. Among individuals older than 65 years, the incidence was comparable to the mean of previous incidence estimates for other populations worldwide.