Study of Chemosensory Enhancement through Neuromodulation Training (SCENT): Design and methodology of a randomized...

Few evidence-based treatments exist for COVID-related persistent smell dysfunction. While smell/olfactory training (ST) has emerged as a widely prescribed, first line treatment, rigorous study is required to determine its efficacy in Long COVID. Additional study and development of adjunctive methods to improve the efficacy of ST is also needed.

This paper details the study design and methodology for a large, at-home, randomized, controlled trial designed to determine whether ST and/or trigeminal nerve stimulation (TNS)-enhanced ST improves Long COVID-related disturbances in smell function, mood, sleep, and cognition. Adults with COVID-related persistent smell dysfunction (N = 180) will be recruited and randomized to self-administer ST, placebo smell training (PBO), or TNS-enhanced ST daily for 12 weeks. Our primary objectives are to i) determine the efficacy of ST, compared to any natural gain in function, on olfactory-specific deficits, ii) determine the TNS-enhanced effects of ST on olfactory-specific deficits, and iii) determine if TNS-enhanced ST, compared to ST, is also more efficacious in the treatment of other symptoms of Long COVID.

Post COVID persistent smell dysfunction and related deficits are relatively common with very few treatment options. Our proposed study will lay the groundwork for further development of ST and TNS as evidence-based treatments for Long COVID.