New insights from a UW study on smell training after COVID
Researchers at the University of Washington in St. Louis investigated whether structured scent training could help people who lost their sense of smell after a COVID-19 infection. The results, published in JAMA Otolaryngology Head & Neck Surgery, suggest that scent training alone may not produce a meaningful average improvement for all patients, but it can benefit some individuals significantly.
The study was a randomized trial that enrolled 275 participants experiencing reduced olfactory function following COVID-19. Participants were assigned to one of two scent exposure approaches or to a control group. In all scent exposure groups, participants sniffed four essential oils for 15 seconds each, with 30 seconds between sessions. In the unimodal condition, they smelled the oils without additional cues. In the bimodal condition, they simultaneously viewed images of the corresponding objects such as a rose, fir tree, or lemon while smelling the oils. A non-training control group served as a comparison baseline.
Statistical analyses tracked changes in olfactory performance from before to after the intervention. On average, the mean improvement across all training participants was 11.6 points. While this average did not reach a threshold that clinicians typically consider meaningful, the bimodal group showed the strongest responses among participants who improved overall.
In terms of clinically meaningful outcomes, about 19% of participants in the control group reported at least a slight improvement, compared with 46% in the bimodal training cohort. The trial indicates that adding visual cues to scent training could enhance the likelihood of smelling improvements for some patients, though not all. The authors emphasize that further research is needed to refine dual-mode training protocols and identify which patients are most likely to benefit. This study contributes to the ongoing discussion about how best to support recovery of the sense of smell after viral loss and highlights the potential role of multisensory approaches in rehabilitation strategies for olfactory disorders.
Overall, the findings suggest scent training remains a promising area for targeted therapy, with bimodal training offering a more favorable signal in this cohort. Healthcare providers should interpret the results as encouraging but not definitive, recognizing that individual responses vary. Ongoing studies will determine whether specific training durations, oil selections, or sensory pairings can reliably yield stronger and more durable improvements for diverse patient populations.