Scientists at the University of Washington in St. Louis have shown that scent training is generally not effective, but does lead to a significant improvement in the sense of smell in some patients. Research published JAMA Otolaryngology – Head and Neck Surgeony.
The randomized trial included 275 patients with reduced sense of smell after COVID. Participants were given four essential oils to sniff for 15 seconds, 30 seconds apart. Some patients were only allowed to smell the oil, while others were shown an image of the object of interest – a rose, a fir tree, a lemon, etc. The second approach scientists call bimodal. A control group that did not receive odor training was used for comparison.
The mean change in olfactory function before and after the intervention was 11.6 points, not considered clinically significant.
However, the highest percentage of participants who experienced an improvement in their sense of smell were in the bimodal training group. A clinically significant improvement (much better or slightly better) was reported by 19% of the control group and 46% of the bimodal participants. The study showed that more work needs to be done on dual-mode training.