DESCRIPTION:(adapted from applicant's abstract) This project is designed to investigate fundamental questions regarding the sensory and cognitive basis of the olfactory event-related brain potential (OERP), as well as to advance clinical application of the OERP in settings where an objective index of olfactory function has importance. Building on the foundation laid by the initial grant period, the current project proposes to further refine the event-related potential technology to optimize its application in both research and clinical contexts. Research during the initial project period has demonstrated that OERPs show age-associated changes in latency and amplitude over the adult lifespan. Nothing is yet known regarding the OERP in children in health or disease. Therefore, the current application proposes to investigate the OERP in normally developing children. Research during the initial project period has demonstrated that adult patients with traumatic brain injury (TBI) show olfactory loss that is objectively reflected in both early N1/P2 and late P3 OERP components. Adults and children with TBI will be followed over time to determine whether recovery of function can be quantified objectively and whether or not the developing olfactory system of children may recover more quickly than that of the adult. Progress during the current grant period has also shown that the OERP is reflective of the olfactory dysfunction in Alzheimer's disease. The magnitude of the effects on the olfactory ERP is substantially larger than has been observed with auditory ERPs. Identification of pre-clinical markers and more accurate early diagnosis of Alzheimer's disease are critically important. This application addresses the issue of early detection of olfactory dysfunction in individuals at risk for Alzheimer's disease. Early detection of the disease will ensure early medical and social intervention for the patient and family caregivers.