Abstract: The present system is directed in various embodiments to devices, systems and methods for detection, evaluation and/or monitoring olfactory dysfunction by measuring and determining the patient's olfactory detection threshold for the left and the right nostril. In some cases, the present invention relates to devices, systems and methods for detecting an asymmetric differential in a patient's relative olfactory detection and/or identification threshold (left vs right nostril) which, when present, may be used as a device to detect, diagnose and/or monitor olfactory deterioration resulting from Alzheimer's disease, and/or the efficacy of treatment regimens therefor over time. Alternatively, general olfactory dysfunction may be evaluated and/or monitored without regard to the individual nostril's performance.