PROJECT SUMMARY/ABSTRACT Long-term cognitive and behavioral deficits are the sequelae of iron deficiency (ID) prior to 3 years of age in children. A causal relationship between early-life ID and brain dysfunction has been established in rodent models, but not as clearly in humans due to a lack of peripheral biomarkers of brain iron status and function. Using a nonhuman primate model that closely mimics human iron biology, brain development and metabolism, we propose to discover novel biomarkers that index brain dysfunction in the pre-anemic stage of ID and evaluate the efficacy of early iron treatment for mitigating ID-induced brain dysfunction. We will serially measure from birth until 12 months, conventional hematological and iron-related indices, and novel proteomic- and metabolomic-based biomarkers in the blood (serum) and intrathecal (CSF) compartments of ID infants and iron sufficient control infants, concluding with neuroanatomical (MRI) and functional (behavior) assessments. Aim 1 will determine how best to employ serum proteomics and metabolomics to detect impending ID- induced brain dysfunction by delineating which analytes and when in the course of ID, the serum proteome and metabolome accurately reflect the brain metabolic, structural and functional impairments. We predict that specific protein and metabolite changes reflecting distinct iron-regulated pathways will be detected in the serum in the pre-anemic period and provide biomarkers of impending brain dysfunction. Aim 2 will quantify and model the sensitivity of conventional hematological and serum iron parameters for detecting brain dysfunction by serially monitoring these parameters relative to the metabolomic and proteomic indices of brain dysfunction in concurrently obtained CSF. We predict that brain ID and dysfunction will be evident prior to the appearance of anemia, indicating that hematological parameters used in clinical practice are insensitive as biomarkers of brain iron and metabolic status. Aim 3 will test the hypothesis that iron treatment prior to anemia is essential to mitigate the adverse neurological effects of ID. ID infants will be randomized to iron treatment either in the pre-anemic stage of ID or after the development of anemia. The efficacy of the two therapies for restoring hematological indices and brain iron status, metabolism, structure and function will be determined. We predict that both treatments will normalize hematological indices, but only iron treatment begun in the pre-anemic stage will fully restore brain iron status, metabolism, structure and function. This project is significant, because it focuses on the benefits of early screening and interventions for improving the neurodevelopment of children at risk for early-life ID. It is innovative because it will employ novel proteomic and metabolomic analyses to simultaneously probe the blood and intrathecal compartments in a primate model that uniquely mimics the iron and metabolic demands of the human infant. The discovery of functional biomarkers will achieve our ultimate translational goal of optimizing screening and treatment strategies in children at risk for early-life brain ID.