Project summary The main objective of this project is to investigate the role of plasma metabolites in the relationship between exposure to PM2.5 and cognitive function in an ethnically diverse aging cohort. This project is a supplement to an ongoing R35 that investigates the role of extracellular vesicles in the relationship between PM2.5 exposure and cognitive decline in the same cohort. The candidate for this supplement is an undergraduate student matriculating into the MPH program at Columbia University in the Fall of 2022. She is expected to graduate from Hunter College with a B.A. degree in Human Biology and Neuroscience in May 2022. The candidate is an American of Puerto Rican descent and the first generation in her family to attend graduate school. For her research and training, she will be mentored by Dr. Baccarelli, PI of the parent grant with support from two other faculty in the department (Dr. Miller and Dr. Kioumourtzoglou). In the proposed project, the candidate will (1) determine the association between exposure to PM2.5 and plasma metabolites, measured using untargeted metabolomics analysis, and characterize the metabolic pathways associated with PM2.5 exposure in the Washington Heights and Inwood Columbia Aging Project (WHICAP) cohort; (2) examine the relationship between plasma metabolites and global cognitive function, measured using mini mental state exam (MMSE) (3) Investigate whether plasma metabolites can mediate the relationship previously identified between PM2.5 and cognitive function in the WHICAP cohort. Through the proposed analyses, the candidate will gain experience and skills in: (1) data management and cleaning, (2) statistical analyses in molecular epidemiology, (3) mediation analysis in environmental epidemiology, (4) writing and communicating research findings. The candidate will also pursue formal training by take courses that are part of the MPH program during the regular school year. The candidate and mentor will meet once a week for training and to discuss progress.