Abstract With the continued growth and aging of the Mexican American (MA) population in the United States, we will see a tremendous expansion of Alzheimer’s disease and Alzheimer’s disease-related dementias (AD/ADRD) in this important group. Understanding and reducing the impact of AD/ADRD in MAs is an important priority for public health and policy making. Currently, there is a critical gap in our understanding of the depth and determinants of disparities in AD/ADRD over time, and potential ways to lessen the impact of these disorders in MA communities. AD/ADRD affects not only the patient, but also family caregivers, who struggle with caring for a loved one facing an uncertain future with many complex decisions about their health and safety. These common yet difficult decisions such as driving cessation, nursing home placement, and use of life-sustaining treatments can have tremendous impact on both patient and caregiver across the spectrum of disease through the end of life. More data are needed on how the growing population of MAs approach these decisions and integrate socioeconomics, culture, and family. This information is necessary to develop future interventions to support these difficult decisions. MA culture also has strong values of family support that may have a positive influence on these decisions and help mitigate some of the negative aspects of caregiving. Using the population-based cohort of MAs and non-Hispanic whites (NHWs) assembled from the highly successful “Cognitive impairment in Mexican Americans: a population-based study (R01 NS100687), we will extend the cohort follow-up to allow for enhanced understanding of ethnic disparities in AD/ADRD over time. The extended follow-up of this cohort will allow us to assess the longer-term trajectory of cognitive impairment affecting MA patients and caregivers and understand the prevalence, determinants, and impact of ethnic disparities in common decisions surrounding AD/ADRD. This project will address the following aims: 1) To extend the long-term assessment of trajectory and ethnic-specific predictors of progression to AD/ADRD, as well as the long-term life impact of AD/ADRD on families and caregivers, among a community-based cohort of Mexican Americans and non-Hispanic Whites in Nueces County, Texas; 2) To assess the determinants and impact of decisions regarding two critical community transitions facing individuals with cognitive impairment: cessation of driving and transition to long-term skilled nursing facilities; and 3) To examine ethnic disparities in end-of-life treatment preferences among individuals with AD/ADRD and their caregivers in a community-based cohort. This proposal will elucidate the impact of ethnicity and socioeconomic factors on AD/ADRD and related decision making across the aging spectrum and assist in the development of targeted decision support interventions among diverse populations.