Long-term positive effects of olfactory training on quality of life and subjective measures of olfactory function

Olfactory dysfunction following viral infection is a debilitating condition. Currently, the recommended treatment for olfactory dysfunction is olfactory training, a systematic and repeated exposure to odors over a prolonged period. A new tool has been proposed for olfactory training that present odors using nasal inserts rather than hand-held devices, to increase ease of training and thereby improving compliance and adherence to the training regimen. Here, we aimed to determine how olfactory training affects subjective experience of quality of life and olfactory function and potential differences training using regular versus the nasal insert setup. Using a randomized controlled design (N = 111), we investigated the effects of an 8-week olfactory training regimen using nasal inserts compared to standard care olfactory training in individuals with post-viral functional hyposmia. Subjective measures of quality of life as well as qualitative and quantitative olfactory function were assessed before and after the training regimen, and during a 1-year follow-up. Overall, participants showed significant and sustained improvements in both subjective olfactory function and quality of life following training. Critically, the nasal insert group demonstrated greater gains in social functioning and quantitative olfactory scores shortly after training, with enhanced olfactory benefits persisting at the 1-year follow-up. The magnitude of changes in quality of life was correlated with subjective olfactory improvement overall, with a stronger association for the nasal insert group. Thus, nasal insert training appears to enhance perceived olfactory function, which coincides with improved quality of life. Findings from this trial provide insight into the benefits of olfactory training on subjective functioning and quality of life, as well as the efficacy of nasal insert training in post-viral hyposmia.