Olfactory training (OT) is employed in the rhinological practice to rehabilitate the sense of smell. OT's potential to restore olfactory sensitivity and increase odor discrimination and identification abilities has been demonstrated in patients with smell loss and aging population prone to olfactory decline. A recent study employing machine-learning algorithms showed that sorting different dilutions of the same odor is an olfactory ability independent from the three most studied olfactory functions (olfactory sensitivity, odor discrimination, odor identification). The presented project aims to verify the effects of OT on the sorting ability in adult and elderly individuals. Participants performed OT with either 4 odors (lemon - citronellal, cloves - eugenol, eucalyptus - eucalyptol, rose - phenyl ethyl alcohol) or odorless propylene glycol (PG) bi-daily for 12 weeks. Before and after the OT their dilution sorting ability was assessed for 3 smells – 2 from the OT set (cloves, rose) and 1 not employed in OT (strawberry). The dilution sorting task involved sorting 6 dilutions of the odor, starting from 1% dilution in PG which was further diluted in 1:2 ratio. Participants used a web-based app to log all OT sessions to control for OT adherence. In adults (n=86; 46 women, M_age=27.7±2.6 years), OT did not affect the dilution sorting ability for any of the odors (all F<.57, all p>.452). Preliminary results obtained for the elderly population (n=60; 50 women, M_age=71.9±5.1 years) also did not reveal any effect of OT on the dilutions sorting ability (all F<.1; all p>.763). Our results suggest no effect of OT on the newly described olfactory ability of sorting odor dilutions and corroborate the notion that dilutions sorting ability is independent from threshold, discrimination and identification abilities. Further research is planned to verify if OT improves dilution sorting ability in patients with anosmia.
Funding: National Science Centre grant (OPUS 2020/37/B/HS6/00288)