PROJECT SUMMARY/ABSTRACT This competing continuation proposal for Years 35-40 of the Health and Retirement Study (HRS) cooperative agreement, including the Harmonized Cognitive Assessment Protocol (HCAP) sub-study, is in response to NIA RFA #AG-24-010. The primary aim of the HRS and HCAP is to design, collect and distribute longitudinal multi-disciplinary data to support research on aging, Alzheimer's Disease and Related Dementias (ADRD), and the health and well-being of the older population. This proposal seeks to collect three additional waves of HRS panel data, one follow-up wave of HCAP data, continue collection of venous blood specimens, continue collection of data on SARS-CoV-2 infection and the COVID-19 pandemic, implement the next scheduled refreshment by adding the second Gen-X cohort in 2028, continue to conduct off-year mail surveys, and implement cost-saving innovations, including expansion of the internet mode for data collection. It will continue the same expanded minority oversample design for the MidGENX cohort as was begun in 2010 and continued through 2022 in which half the new sample consists of black or Hispanic households. The new MidGENX cohort will be fully integrated into the HRS design, including collection of biomarkers, DNA, and linkage consents to Social Security and other records as appropriate. HRS and HCAP provide uniquely rich, nationally representative longitudinal data that can simultaneously support cross-sectional descriptions of the U.S. population age 51+, longitudinal studies of a given cohort over a substantial period of time, and research on cross-cohort trends. The HRS and HCAP projects create a data system extending beyond the core survey data. One component is linkages to administrative data, including Social Security earnings and benefit records, Medicare utilization and diagnostic records, including Part C, Minimum Data Set and Medicaid records, employer pension records, Veterans Health Administration data and the National Death Index. We will expand resources of contextual data linked through geographic locations to support research on the exposome for ADRD. We will continue to expand access to these secure data through virtual enclaves. Another component is genome-wide genotyping data from consenting respondents distributed through NIAGADS and a repository of blood samples including cryopreserved cells. HRS and HCAP provide public use data designed to allow the full power and creativity of America's scientific community to address the challenges of an aging population, including the prevention of cognitive decline and ADRD. HRS and HCAP are making a significant impact on research on aging and ADRD through investigator-initiated research which uses the HRS as an input without charge to researchers or granting agencies. Over 4,600 peer-reviewed journal publications have appeared; more than 2,000 in the past six years. HRS and HCAP support training of new scientists with 750+ doctoral dissertations using these data.

PROJECT NARRATIVE This proposal seeks continuation of the Health and Retirement Study (HRS) core data collection for three more waves and the Harmonized Cognitive Assessment Protocol (HCAP) for one more wave, including the introduction of a new younger cohort in 2028 to refresh the HRS sample following the steady state sampling design. It will build the repository of biosamples, expand data linkages of the ADRD exposome, maintain the expanded representation of minorities, and further expand data access to maintain the studies as the premier source of data on public health of the older population, with a special focus on ADRD. Cost savings will be achieved through innovative methods.