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Background: Rapid demographic ageing is a growing public health issue in many low- and middle-income countries (LAMICs). Mild cognitive impairment (MCI) is a construct frequently used to define groups of people who may be at risk of developing dementia, crucial for targeting preventative interventions. However, little is known about the prevalence or impact of MCI in LAMIC settings., Methods and Findings: Data were analysed from cross-sectional surveys established by the 10/66 Dementia Research Group and carried out in Cuba, Dominican Republic, Peru, Mexico, Venezuela, Puerto Rico, China, and India on 15,376 individuals aged 65+ without dementia. Standardised assessments of mental and physical health, and cognitive function were carried out including informant interviews. An algorithm was developed to define Mayo Clinic amnestic MCI (aMCI). Disability (12-item World Health Organization disability assessment schedule [WHODAS]) and informant-reported neuropsychiatric symptoms (neuropsychiatric inventory [NPI-Q]) were measured. After adjustment, aMCI was associated with disability, anxiety, apathy, and irritability (but not depression); between-country heterogeneity in these associations was only significant for disability. The crude prevalence of aMCI ranged from 0.8% in China to 4.3% in India. Country differences changed little (range 0.6%-4.6%) after standardization for age, gender, and education level. In pooled estimates, aMCI was modestly associated with male gender and fewer assets but was not associated with age or education. There was no significant between-country variation in these demographic associations., Conclusions: An algorithm-derived diagnosis of aMCI showed few sociodemographic associations but was consistently associated with higher disability and neuropsychiatric symptoms in addition to showing substantial variation in prevalence across LAMIC populations. Longitudinal data are needed to confirm findings-in particular, to investigate the predictive validity of aMCI in these settings and risk/protective factors for progression to dementia; however, the large number affected has important implications in these rapidly ageing settings.

Objectives: To assess the association between tobacco consumption and dementia using the same methodology in seven developing countries, testing the specific hypotheses that higher exposure to tobacco is associated with a higher prevalence of dementia, that the association is limited to smoked tobacco and is stronger for vascular dementia compared to Alzheimer's disease., Methods: Cross-sectional surveys conducted on individuals aged 65+. A total of 15 022 residents in specified catchment areas were assessed face-to-face using a standardised protocol, which included dementia diagnosis and detailed information on past and current tobacco consumption, and on important potential confounders of this association., Results: A high proportion of participants were never smokers (52% in Dominican Republic to 83% in Peru), most of those who ever used tobacco in China and India were still smoking at age 65 and above (80% and 84%, respectively). There was a positive association between history of tobacco smoke exposure (pack years up to age 50) and dementia (pooled PR = 1.003; 95%CI 1.001-1.005), Alzheimer's disease (pooled PR = 1.007; 95% CI, 1.003-1.011) and Vascular Dementia (pooled PR = 1.003; 95% CI = 1.001-1.005). These associations were attenuated but remained significant if exposure after the age of 50 was included. In India there was no association between smokeless tobacco and dementia., Conclusions: Dementia in developing countries appears to be positively associated with history of tobacco smoking but not smokeless tobacco use. Selective quitting in later life may bias estimation of associations., (Copyright © 2011 John Wiley & Sons, Ltd.)

Background: The number of older people is set to increase dramatically worldwide. Demographic changes are likely to result in the rise of age-related chronic diseases which largely contribute to years lived with a disability and future dependence. However dependence is much less studied although intrinsically linked to disability. We investigated the prevalence and correlates of dependence among older people from middle income countries., Methods: A one-phase cross-sectional survey was carried out at 11 sites in seven countries (urban sites in Cuba, Venezuela, and Dominican Republic, urban and rural sites in Peru, Mexico, China and India). All those aged 65 years and over living in geographically defined catchment areas were eligible. In all, 15,022 interviews were completed with an informant interview for each participant. The full 10/66 Dementia Research Group survey protocol was applied, including ascertainment of depression, dementia, physical impairments and self-reported diagnoses. Dependence was interviewer-rated based on a key informant's responses to a set of open-ended questions on the participant's needs for care. We estimated the prevalence of dependence and the independent contribution of underlying health conditions. Site-specific prevalence ratios were meta-analysed, and population attributable prevalence fractions (PAPF) calculated., Results: The prevalence of dependence increased with age at all sites, with a tendency for the prevalence to be lower in men than in women. Age-standardised prevalence was lower in all sites than in the USA. Other than in rural China, dementia made the largest independent contribution to dependence, with a median PAPF of 34% (range 23%-59%). Other substantial contributors were limb impairment (9%, 1%-46%), stroke (8%, 2%-17%), and depression (8%, 1%-27%)., Conclusion: The demographic and health transitions will lead to large and rapid increases in the numbers of dependent older people particularly in middle income countries (MIC). The prevention and control of chronic neurological and neuropsychiatric diseases and the development of long-term care policies and plans should be urgent priorities.