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. More specifically, the present invention relates to devices, systems and methods for detecting an asymmetric differential in a patient's olfactory detection threshold (left vs right nostril) which, when present, may be used as a tool to screen, detect, diagnose and/or monitor relative olfactory deterioration resulting from Alzheimer's disease. A preferred embodiment comprises cascading aromas by serially administering more than one pure odorant to the patient's nostrils, left vs right, with measurement of the time, or numbers of breaths, required to cognitively notice the pure odorants' presence.