Since 1992, the Health and Retirement Study (HRS, a cooperative agreement between the National Institute on Aging (NIA) and the University of Michigan, NIA U01AG009740) has been the largest, representative longitudinal study of Americans over age 50. Built on a national probability sample with oversamples of minorities, it is the model for a network of harmonized international longitudinal studies of work, health, social, psychological, family and economic status through critical life transitions and trajectories related to retirement, economic security, health and function, social and behavioral function and support systems.  Core interviews take place every two years and are supplemented by mail surveys, biomarker collections, administrative linkages, and other sources.

The HRS study is a cohort study and is nationally-representative of US residents over the age of 50 and their spouse/partners. Measurement of cognition has been part of the core HRS survey since the beginning in 1992. In addition, two separate supplemental studies provide in depth cognition measurement. HRS is also linked to CMS data for claims-based diagnoses.
See: https://hrs.isr.umich.edu/data-products/cognition-data and https://hrs.isr.umich.edu/data-products/restricted-data/cms-data

From the beginning, a key element of the HRS sample design has been oversampling of African American and Hispanic populations in each new cohort to serve the important goal of supporting racial and ethnic disparities research (Jackson, Lockery, & Juster, 1996). Ofstedal and Weir (2011) demonstrated that HRS has been successful in both recruiting and retaining African American and Hispanic populations. Building on this success, HRS implemented additional screening in the 2010 and 2016 cohort enrollments to expand the number of minority participants, with similar plans for 2022 underway. The current active sample of approximately 22,500 includes approximately 4,700 African-American and 2,600 Hispanic participants. With the addition of data from the Harmonized Cognitive Assessment Protocol (HCAP), HRS is now also a major resource for studying racial and ethnic disparities in Alzheimer’s Disease and Alzheimer’s Related Dementias (AD/ADRD). HCAP was specifically designed to enable epidemiological research on variation in the incidence, prevalence, and impact of AD and related dementias (Langa et al., 2019).