PROJECT SUMMARY The primary goal of this administrative supplement is to collect necessary data and conduct data analysis in order to expand understanding of early life exposures to armed conflict as they influence risks for Alzheimer’s disease and related dementias (ADRD). The focus of the administrative supplement is the creation of data for measuring ADRD and analyzing ADRD risk factors among a subsample of the Vietnam Health and Aging Study (VHAS), an ongoing longitudinal study of 2,447 older adult survivors of the American War residing in four districts of northern Vietnam. The study team will assess ADRD through a cognitive performance test instrument, the Community Screening Instrument for Dementia (CSI-D), which has been validated widely in low-middle income contexts. The CSI-D, which involves both cognitive testing for the respondent and an informant interview with a close family member, will be subject to validation in the VHAS setting. In addition to the CSI-D, using whole blood samples slated for collection during the second wave of VHAS, the project supplement will collect and assay homocysteine and a blood-based biomarker diagnostic panel for ADRD adapted from O’Bryant et al. The parent study, which funds Wave I data collected in 2018 and Wave II collection scheduled for 2021, provides detailed, longitudinal data on myriad risk factors for ADRD that have been identified in other, largely western populations, namely severe psychological stressors of war; dioxin exposure due to widespread spraying of Agent Orange and other chemical defoliants across Vietnam; and experience of adverse conditions during childhood and young adulthood, including severe food shortage and community-level bombing exposure. The scope of work within the proposed supplement is to create additional data on nutritional intake, to obtain assays of the ADRD biomarker homocysteine and a 10-analyte ADRD biomarker panel, and to perform analyses which explore war-related stressors as they influence cognitive functioning and ADRD risk. Armed conflict has been most pervasive in developing countries like Vietnam, where the population both moving into old age and having directly experienced war is growing rapidly, but where we have virtually no knowledge of the long-term effects of war exposure on ADRD. This study directs attention toward war as it may contribute to or detract from healthy aging, especially neurodegenerative diseases like ADRD which impose heavy burdens upon healthcare and caregiving institutions in low-middle income countries. To meet our administrative supplement study goals, we will: a) create and implement a supplementary survey module which examines ADRD as assessed by the CSI-D within a subset of 450 members of the VHAS, selected according to a random quota sampling method that yields significant statistical power for assessing ADRD across levels of war stress exposure; b) perform assays of homocysteine and a ADRD biomarker panel using whole blood sa...