IntroductionAlzheimer’s disease and related dementias can be considered the epidemic of the 21st century. Particularly, the predicted growth in the size of elderly populations in low-income and middle-income countries is expected to produce a dramatic surge in dementia prevalence and incidence. Although a rising burden of dementia presents an urgent challenge for India, previous efforts to study dementia in the country have relied on non-representative samples in geographically restricted regions. The Harmonised Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) will provide rich, population-representative data on late-life cognition and dementia and their risk factors for the first time in India.MethodsThe LASI-DAD will recruit a sample of 3000 people aged 60+ years. Their family members or friends, whom respondents nominate as informants, participate in the computer-assisted personal interview. The study sample is drawn from the ongoing, nationally representative Longitudinal Aging Study in India, a multipurpose panel survey of aging. We aim to collect rich data on cognitive and neuropsychological tests, informant reports, and epidemiological data through a comprehensive geriatric assessment, and venous blood collection and assays. For a subsample, we collect neuroimaging data. Data collection is currently in progress in 14 States and Union Territories of India. Clinicians will provide clinical consensus diagnosis based on the Clinical Dementia Rating.Ethics and disseminationEthics approval was obtained from the Indian Council of Medical Research and all collaborating institutions. Anonymised data will be available for the larger research community through a secured website hosted by the Gateway to Global Aging Data platform. Research findings from the LASI-DAD team will be disseminated through journal publications and presentations at professional conferences.

BACKGROUND/OBJECTIVESTo provide high‐quality data on older adults in India that will enable an in‐depth study of late‐life cognition and dementia in India and cross‐country analysis of risk factors for cognitive aging and dementia.DESIGNThe Longitudinal Aging Study in India (LASI) is a nationally representative survey of health, economic, and social well‐being of the Indian population aged 45 and older. Its large sample of more than 70,000 older adults represents not only the country as a whole but also each state. LASI‐Diagnostic Assessment of Dementia (DAD) is an in‐depth study of late‐life cognition and dementia, drawing a subsample of over 3,000 LASI respondents aged 60 and older.SETTINGParticipants were interviewed at home or in a participating hospital according to their preferences.PARTICIPANTSAdults aged 60 and older (N = 3,224), along with 3,191 informants.MEASUREMENTSRespondents underwent a battery of cognitive tests, and informants were interviewed about their cognitive and health conditions. A common set of cognitive tests was selected to enable international comparisons, and additional cognitive tests suitable for illiterate and innumerate populations were also selected. Rich data on risk factors of dementia were collected through health examination, venous blood assays, and genotyping.RESULTSThe response rate was 82.9%, varying across sex, education, and urbanicity. Data are available to other researchers.CONCLUSIONLASI‐DAD provides an opportunity to study late‐life cognition and dementia and their risk factors in the older population in India and to gain further insights through cross‐country analysis by pooling data from its international sister studies. J Am Geriatr Soc 68:S5‐S10, 2020.

Introduction: Prior estimates of dementia prevalence in India were based on samples from selected communities, inadequately representing the national and state populations.Methods: From the Longitudinal Aging Study in India (LASI) we recruited a sample of adults ages 60+ and administered a rich battery of neuropsychological tests and an informant interview in 2018 through 2020. We obtained a clinical consensus rating of dementia status for a subsample (N = 2528), fitted a logistic model for dementia status on this subsample, and then imputed dementia status for all other LASI respondents aged 60+ (N = 28,949). Results:The estimated dementia prevalence for adults ages 60+ in India is 7.4%, with significant age and education gradients, sex and urban/rural differences, and cross-state variation.Discussion: An estimated 8.8 million Indians older than 60 years have dementia. The burden of dementia cases is unevenly distributed across states and subpopulations and may therefore require different levels of local planning and support.

OBJECTIVESTo test whether a relatively complex model of human cognitive abilities based on Cattell‐Horn‐Carroll (CHC) theory, developed mainly in English‐speaking samples, adequately describes correlations among tests in the Longitudinal Aging Study in India–Diagnostic Assessment of Dementia (LASI‐DAD), and to develop accurate measures of cognition for older individuals in India.DESIGNLASI‐DAD participants were recruited from participants aged 60 years and older from 14 states in the core LASI survey, with a stratified sampling design.SETTINGParticipants were interviewed at home or in a participating hospital, according to their preferences.PARTICIPANTSCommunity‐residing older adults aged 60 years and older (N = 3,224).MEASUREMENTSA variety of cognitive tests were administered during two pretests and chosen for their appropriateness for measuring cognition in older adults in India and suitability for calibration with the core LASI survey and the Harmonized Cognitive Assessment Protocol.RESULTSWe evaluated the factor structure of the test battery and its conformity with a classical CHC factor model that incorporated measurement models for general cognition, five broad domains (orientation, executive functioning, language/fluency, memory, and visuospatial), and five narrow domains (reasoning, attention/speed, immediate memory, delayed memory, and recognition memory) of cognitive performance. Model fit was adequate (root mean square error of approximation = 0.051; comparative fit index = 0.916; standardized root mean squared residual = 0.060).CONCLUSIONWe demonstrated configural factorial invariance of a cognitive battery in the Indian LASI‐DAD using CHC theory. Broad domain factors may be used in future research to rank individuals with respect to cognitive performance and classify cognitive impairment. J Am Geriatr Soc 68:S11‐S19, 2020.

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