Effects of physical exercise and olfactory training with pleasant and unpleasant odors on verbal fluency and depression

Mechanisms of olfactory training (OT) in older adults require a more thorough investigation, considering its potential beneficial effects in age-related olfactory, cognitive, and affective decline. To address this question, we examined the role of OT odor hedonics in 128 participants aged between 50 and 85 years (Mage = 68.2 ± 7.4; 105 women and 23 men). Additionally, we explored the role of physical activity in olfactory function, depression scores, and verbal fluency. Participants were randomly assigned to one of four groups, of which two performed OT with either a) pleasant or b) unpleasant odors, or c) performed physical exercises and no OT or d) a control group without OT or physical exercises. Results indicate a beneficial effect of OT, both with pleasant and unpleasant odors, on one key domain of cognitive function, namely verbal fluency. Furthermore, physical exercise alone also caused an increase in verbal fluency. Finally, a significant beneficial effect of OT on depression score was noted, but only in the group that displayed relatively robust depression symptoms in the pre-training session. OT may be of particular use for older people due to their risk of age-related cognitive decline and depression.