This project investigates the relationship between the oral microbiome, gut-derived short-chain fatty acids (SCFAs), and neurocognitive outcomes in HIV-infected (HI) and HIV-unexposed, uninfected (HUU) Nigerian youths. Conducted as an extension to the uBLOOM study, this analysis focuses on a subset of participants to evaluate the oral–gut–brain axis in the context of HIV, which remains incompletely understood. SCFA concentrations were quantified from stool samples and correlated with existing oral microbiome and neurocognitive data, collected using NIH Toolbox and Neuroscreen metrics. Preliminary results suggest that although some bidirectional associations between pairs of domains were more pronounced in specific groups, consistent evidence for an integrated three-way link across all domains was missing. These findings underscore the complexity of microbial–metabolic–cognitive interactions in youth affected by HIV and highlight the potential of oral and gut microbiome–based markers to predict neurodevelopmental and cognitive health.