PROJECT SUMMARY Hispanic/Latinx (henceforth, Latinx) adults currently have a 50% greater risk for Alzheimer’s disease and related dementias (ADRD) compared to non-Latinx White adults. Latinx populations experience greater social, environmental, and economic disadvantage that heightens psychosocial stress, increasing vulnerability for poor cognitive health outcomes. Perceived ethnic discrimination is a psychosocial stressor that reflects individual experiences of being treated badly or unfairly because of their ethnicity, and may be a critical risk factor for reduced cognitive health. Latinxs in the U.S. are diverse in multiple ways warranting a within population study of Latinxs. Mexican-origin adults constitute 62% of the Latinx population in the U.S. Thus, evaluating risk and protective factors in Mexican-origin adults will elucidate mechanisms of cognitive health inequities in the largest portion of the Latinx U.S. population. Midlife is a critical time to evaluate precursors of disparate cognitive health outcomes in late life and identifying predictors of cognitive health in this developmental stage can inform early prevention and intervention efforts. The proposed research will uncover how perceived ethnic discrimination is associated with cognitive function in Mexican-origin adults in midlife by implementing a within day, ecological momentary assessment, protocol to measure discrimination and cognitive functioning throughout the day. This R21 study will break new ground in understanding increased risk of ADRD within the Latinx population by examining cognitive functioning associated with discrimination when it occurs in daily life, by incorporating linguistically and culturally appropriate ambulatory assessments of daily experiences and cognition using mobile devices. The proposed protocol will be inclusive and accessible on the language of surveys and assessments used, and will accommodate baseline data collection settings to garner inclusivity and reduce selection bias in this area of research. Study investigators will collect data from 100 Mexican-origin adults between the ages of 45 to 65 who live in Central Texas, to test the aims of the study. Aim 1 will evaluate daily associations between experiences of discrimination and performance on cognitive tasks of attention and memory. This aim will also test if the observed links vary across age. Aim 2 will test psychological mechanisms (e.g., increased negative affect) from experiences of discrimination to cognitive functioning. Aim 3 will investigate psychosocial sources of resilience in the association between experiences of discrimination and cognitive function in Mexican-origin adults by testing the moderating role of individual differences in psychological (e.g., purpose in life) and social (e.g., familism) resources. This study will increase understanding of risk and protective factors for reduced cognitive health among Mexican-origin adults—a priority sub-population in the National I...