Project Summary Smell disorders are highly impactful in daily life. Gas leaks and spoiled food are undetectable dangers. Adequate nutrition is compromised as food become unpalatable without the core contribution smell plays in flavor perception. Affected individuals also feel disconnected from the world and other people, contributing to an increased incidence of depression. Smell disorders may also be early indicators of other serious health problems such as rhinosinusitis, skull base tumors, cerebrospinal fluid leaks, or neurological diseases such as Alzheimer's disease, Parkinson's disease or multiple sclerosis. Smell disorders are also much more common than most people believe, with one major pre-COVID-19 study finding that over 12% Americans age 40 and older had hyposmia (a reduced ability to smell) or anosmia (an inability to smell). However, despite substantial prevalence and significant health impacts, smell disorders remain routinely underdiagnosed, in part because routine olfactory screening is not a part of primary care. A major impediment to incorporating objective, validated smell tests in routine healthcare is that the current options are too time consuming and/or expensive. Thus, a new option is needed if smell testing is to be embraced by medical providers as a part of routine screening, analogous to the ubiquitous Snellen eye chart and handheld audiometer used in many primary care clinics. Roughly a third of US adults receive an annual physical or preventive care visit. Including smell tests in such visits would result in over 75 million tests per year. When an olfactory disorder is diagnosed or suspected, it typically results in referrals to specialists (e.g., neurology, otolaryngology) and in procedures such as surgeries, imaging, and endoscopy that are billable to health insurance. Thus, we expect that a low cost, rapid smell test would provide a substantial return on investment for healthcare systems. To address this unmet need for a robust, rapid, inexpensive, cross-cultural test of olfactory function that can be administered in varied settings, we designed the Adaptive Olfactory Measure of Threshold (ArOMa-T). The ArOMa-T includes multiple concentrations of a single odorant spaced over several log units of concentration and encapsulated in peel- and-burst labels on a foldable card. The card is paired with an adaptive algorithm, implemented via a website or app, that guides the patient through a sequence of odorant concentrations where each is selected based on prior responses. By skipping non-informative concentrations, this test rapidly determines the patient's odor detection threshold. The ArOMa-T can be self-administered and produced inexpensively at scale. In this proposal, we will pursue three Specific Aims to move the ArOMa-T towards commercialization: we will (1) compare the performance of the ArOMa-T against other validated smell tests; (2) develop an accompanying application for real-time processing of the adaptive ...