Task-Specific Effects of Acute Stress Exposure on Olfactory Discrimination in Young Men

Acute stress has been proposed to affect the ability to detect or identify odors in humans. However, whether and how acute stress affects odor discrimination remain less explored. Forty-six healthy males (mean age 21.3 ± 1.7 years) participated in an acute psychosocial stress (Socially Evaluated Pressor Cold Test, SECPT) and a control session in randomized order. Odor discrimination performances were assessed using the “Sniffin’ Sticks” discrimination test, the binary odor mixture discrimination task (ABX task), and the enantiomer discrimination task. Salivary cortisol, subjective stress, and emotional states were measured throughout the experiment. After the SECPT, participants showed an enhanced “Sniffin’ Sticks” discrimination score, but no changes beyond chance level were identified in the ABX discrimination task or enantiomer discrimination task. Moreover, there was a negative correlation between the peak level of subjective stress after acute stress exposure and a decrease in stress-related ABX discrimination performance. Furthermore, state anxiety level was positively associated with an increase in stress-induced camphor (+) (−) discrimination score. These results were discussed in light of task features and the complexity of odor discrimination as a high-order cognitive ability. Future studies should investigate the specific qualities of odors involved in discriminating between them and how they may be affected by acute stress. Stress-related emotional states and measurements of odor quality discrimination should also be taken into careful consideration in the future. Additionally, the results should be interpreted with caution as only male participants were included in this study.