Examination of Olfactory Training Effectiveness in Relation to Its Complexity and the Cause of Olfactory Loss

Objective: Although the effectiveness of olfactory training (OT) had already been documented, the optimal regimen for such training remains unexplored. We examined whether the complexity of OT, namely alteration of odor quantity and quality, increases its effectiveness. Design: One-hundred eight patients (M-age = 60.1 1) with postinfectious (n = 57) or idiopathic (n = 51) olfactory dysfunction underwent OT preceded and followed by examination of olfactory function. Methods: Subjects were randomly assigned to one of the three experimental conditions: 1) simple training comprising four basic, single-molecule substances; 2) complex training involving four odor mixtures; and 3) odor-altering training in which patients changed sets of mixtures every 2 months. Results: The analysis of variance revealed that the benefit seen in this sample was not affected by the complexity of OT with regard to odor mixtures or alteration of odor type. The highest increase of the Sniffin' Sticks (Burghardt GmbH; Wedel, Germany) threshold, discrimination, and identification (and overall TDI) score was observed in postinfectious patients. Conclusion: We conclude that the outcomes of OT are not strongly influenced by the training regimen. However, further investigation of OT regimens is required, particularly with regard to training duration.