Olfaction is linked to cognitive functioning due to neural connections between the olfactory and limbic systems. One of the cognitive functions that olfaction is associated with is verbal fluency, the ability to generate words or produce fluent speech. Previous studies show that olfactory training (OT) improves the general verbal fluency. This study examined the effects of OT on verbal fluency with respect to a general and olfaction-related wording in healthy adults (without olfactory or cognitive impairments). A total of 86 adults (54% women; M_age=27.7±2.61 years) and 60 elderly (83% women; M_age=71.9±5.07 years) were invited to the study. Participants underwent a 12-week OT wherein they sniffed four odors: (1) citronellal (lemon); (2) phenyl ethyl alcohol (rose), (3) eucalyptol (eucalyptus); (4) eugenol (cloves) twice a day. The control group performed the same activity with odorless propylene glycol. Compliance was monitored using a dedicated web-based application. Verbal fluency was measured by listing as many words as possible within 60 seconds: either (a) grocery or (b) fragrance products. Participants listed items from the same category in both the pre- and post-OT measurement. OT did not significantly impact verbal fluency, regardless of the type of items listed and age (both F<2.29 and p>0.136). Post-hoc analysis showed a trend-level increase in verbal fluency in the elderly OT group (p=0.58), regardless of semantic category (grocery vs fragrance products) These findings suggest that OT does not enhance verbal fluency in adult individuals who are likely to be at the peak of their cognitive and olfactory performance, but might slightly benefit verbal fluency in elderly.
This work was supported by National Science Centre in Poland (#2020/37/B/HS6/00288 awarded to AO).