Core C: Biomarker and Biobanking Core—Abstract The Biomarker and Biobanking Core will provide scientific direction and oversight of biomarker and biobanking samples for the entire Health, Aging and Dementia in South Africa: A Longitudinal Study (HAALSI) Program. The Core is led by two Co-PIs who will oversee a group of international experts in the fields of epidemiology, genomics, bioinformatics, epigenetics, biostatistics, and biomarker analysis. A biomarker is defined by NIH as a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention. We further divide biomarkers into two broad categories for the purpose of Core C: (1) those that do not require a biological sample to be collected and/or stored (e.g., imaging, blood pressure); and (2) those that require a biological sample to be further analyzed, whether at the point of care (e.g., blood glucose) or in a laboratory (e.g., urine sodium, DNA).This Core will allow us to continue our commitment to longitudinal sample collection in Agincourt and the coordinated use of biomarkers across all four research projects. The proposed HAALSI National survey will augment the HAALSI Agincourt community study with biomarker data from a nationally representative cohort. The growing collection of baseline and new biomarker data related to dementia, cognitive function, cardiometabolic diseases, HIV, and inflammation will inform many research questions and provide opportunities for comparative data for analyses. In particular, we are collecting and analyzing novel biomarkers for dementia and heart failure that have not been measured extensively in African populations. Neuroimaging and plasma samples for amyloid beta (Aβ), phosphorylated tau (p-tau), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) will allow for improved phenotyping and relationships between risk factors for dementia. Further, novel cardiac biomarkers of echocardiography and plasma levels of NT-pro brain natriuretic peptide (BNP), cardiac troponin I, and Galactin-3 will be measured for longitudinal evaluation for the first time in an African cohort, allowing for improved phenotyping and risk stratification for cardiometabolic disease morbidity and mortality.