Anxiety-related shifts in smell function in children and adolescents

Abstract

Anxious adults show changes in smell function that are consistent with a durable shift in sensitivity toward particular odorants and away from others. Little is known regarding the development of these changes, including whether they exist in youth, are stable during the transition from childhood to adolescence, and whether odorant properties (e.g. trigeminal features, hedonic valence) affect anxiety-related differences in detection. To address this, we measured smell detection thresholds to phenyl ethyl alanine (PEA), a rose-like odorant with little trigeminal properties, and guaiacol (GUA), a smoke-like odorant with high trigeminal properties. These thresholds were measured at baseline and after an acute stress challenge, the Trier Social Stress Tests, in 131 healthy youth (in 4th, 7th, and 10th grades, age 9–16 years) that reported normal to elevated levels of anxiety. At baseline, high anxious youth exhibited heightened sensitivity to GUA coupled with reduced sensitivity to PEA, as well as a further exaggeration of this bias with acute stress. Importantly, sex, age, and hedonic valence moderated the relationship between trait anxiety and sensitivity to both odorants. Smell function and its aberrations are often overlooked in the literature on biomarkers of stress and anxiety. Taken together with the extant literature, these findings suggest that greater attention is warranted to characterize potential novel olfactory therapeutic targets—across the lifespan.

On the state-dependent nature of odor perception

“…Beyond circadian and sleep-related states, olfactory function has been shown to vary with emotional states, most notably anxiety. Three recent studies suggest that anxiety modulates odor perception (Pacharra et al, 2016;Hoenen et al, 2017;Cortese et al, 2021). All of these implemented some version of the Trier Social Stress Test (TSST).…”

“…In one of them, participants were shown to be more sensitive to a foul odor (2-mercaptoethanol, which smells like sewage) in the anxious state (Pacharra et al, 2016). In the other, participants with high anxiety severity were shown to be more sensitive to the scent of smoke (guaicol) than the scent of rose (PEA), when compared to participants with low anxiety severity (Cortese et al, 2021). Although the latter result speaks more to trait anxiety than state anxiety, this relationship was further accentuated by the TSST.…”