The Harmonized Diagnostic Assessment of Dementia for the Longitudinal Aging Study in India (LASI-DAD) is an in-depth study of late-life cognition and dementia, drawing on a subsample of the Longitudinal Aging Study in India (LASI). LASI is a nationally representative survey of the health, economic status, and social well-being of the Indian population aged 45 and older. Its large sample of 72,000+ adults represent not only the country as a whole but also every state.

To study late-life cognition and dementia in LASI-DAD, we recruited a sub-sample of 4,000+ LASI respondents aged 60 and older from 18 states and union territories across the country, expanding to 22 states in Wave 2. We administered in-depth cognitive tests and interviewed a family member or friend, who study participants nominated as informants. We carefully selected a set of cognitive tests to enable international comparisons with other dementia studies around the world, including the U.S. HRS-HCAP (Harmonized Cognitive Assessment Protocol) and prior studies in India.

LASI-DAD also collected rich data on risk factors through geriatric assessments (e.g., anthropometry, blood pressure measurements, hearing tests, venous blood assays), as well as nutritional and environmental assessments (exposure to air pollution and neighborhood conditions). For a sub-sample, brain imaging data were collected using the Alzheimer’s Disease Neuroimaging Initiative (ADNI) protocol. Whole genome sequencing has also been completed to better define the mutational spectrum underlying dementia risk.