Olfactory training enhances semantic verbal fluency in healthy older adults, but only for individuals with low baseline performance

Abstract Olfactory training (OT), a structured exposure to odors, is commonly used by otorhinolaryngologists to treat olfactory dysfunction. However, OT has been shown to improve cognition of people with cognitive or olfactory impairments and slow the age-related cognitive decline. This study investigated whether OT could enhance cognitive functions in older adults with an intact sense of smell, compared to younger adults. We hypothesized that OT would improve semantic verbal fluency and working memory in the experimental group, with no significant changes in the placebo group. The final sample comprised 184 participants aged 24-94 years (Mage=51.84 ± 23.25 years), including 83 young adults (53% women, Mage=26.71 ± 2.62 years) and 101 older adults (88% women, Mage=72.49 ± 5.40 years). For the semantic verbal fluency task, they listed as many items as possible within one of two semantic categories: (1) grocery products or (2) fragrant items, within a 60-second time limit. To measure working memory, participants completed a digit span task where they repeated sequences of digits aloud. In older adults performing olfactory training, OT led to a marginal increase in semantic verbal fluency, regardless of semantic category, while no significant changes were observed in the older placebo group or in young adults. This effect was mainly driven by individuals with lower scores at baseline. Our findings suggest that OT can benefit semantic verbal fluency in the healthy geriatric population with lower baseline scores, but these results urge similar testing in clinical groups with compromised verbal functions.