Determining Enhanced Sensitivity to Odors due to Anxiety-Associated Chemosignals with GC

While the behavioral effects of anxiety chemosignals on recipients are established, it is still unknown whether odor sensitivity can be modulated by such stimuli. A joint study between the University of Erlangen-Nuremberg (Erlangen, Germany) and the Fraunhofer Institute for Process Engineering and Packaging (Freising, Germany) tested recipients’ sensitivity to phenylethyl alcohol (PEA) and n-butanol after exposure to anxiety chemosignals, neutral chemosignals, and blank condition. As fourth condition, a horror movie was shown, to compare the effects of visual stimuli and chemosignals on odor sensitivity. The composition of the applied chemosensory stimuli was also investigated using untargeted one-dimensional gas chromatography-mass spectrometry (GC-MS) and -olfactometry (GC-O). A paper based on this research was published in Communications Chemistry (1).

The composition of body odor will vary between individuals, and will even differ within individuals depending on their condition. Because of these variations, body odors will convey trait- and state-dependent information pertaining to an individual’s genetics, age, sex, hygienic and nutrition habits, as well as their health status, reproductive state, or experienced emotions, playing an important role in non-verbal communication between individuals (2). Chemical cues and signals connected to various emotional conditions affect the behavior of recipients (3,4). For example, the chemosignals in axillary odor samples obtained from fearful individuals increase cognitive performance of recipients.

Research conducted at Rice University revealed that the test subjects participating could solve tasks more accurately while smelling fear sweat compared to either neutral sweat or a control odor (5). Anxiety chemosignals also increase the amplitude of the startle reflex, pointing to pre-attentive priming of defensive behavior through the smelling of anxiety sweat (6). In addition, anxiety signals activate areas within the brain which are associated with the regulation of emphatic feelings and the emotional control system (7) This information, taken together, suggests that fear and anxiety chemosignals will enhance sensory acquisition behavior and lead to a faster and more accurate reaction in a dangerous situation (8). The researchers involved with the joint study hypothesized that fear and anxiety chemosignals also modulate the perception of environmental odors, manifested in a higher olfactory sensitivity and thus aimed to explore if the perception of anxiety chemosignals leads to an increase of sensitivity for environmental odors. In addition, they aimed to compare the effects of chemosignals with those of a complex visual stimulus (1).

A total of 24 axillary chemosignal samples from anxious (A) and emotionally neutral states (N) were collected from the left and right underarms of 12 females with dental anxiety (mean age = 41.0 years, SD = 12.5 years). A trained panel determined odor attributes to establish and compare the overall odor profile of anxiety and neutral chemosignals. In the orthonasal sensory evaluation, six odor qualities were selected for the description of the perceived smells; sweaty, citrus-like, grapefruit-like, soapy, waxy and cotton-like. Solvent extracts obtained from anxiety and neutral chemosignals and blank samples were analyzed using GC-O. To screen for potent odorants in the samples, one pooled sample was analyzed per sample type (anxiety, neutral, blank). In total, 51 compounds were olfactorily detected in the anxiety sample, 44 in the neutral sample, and 34 in the blank sample. Anxiety and neutral chemosignals (n = 12 per condition) were solvent extracted and analyzed using GC-MS. To visualize the relation between the composition of anxiety and neutral samples, principal component analysis (PCA) was performed (1).

The data revealed that anxiety chemosignals increase odor sensitivity of the recipients, as sensitivity for PEA was significantly higher in the anxiety condition compared to the non-body odor blank condition. However, odor sensitivity was only increased for PEA and not for n-butanol. Also, no significant difference in odor sensitivity was found when comparing the anxiety with the neutral chemosignal condition (1).

The authors of the study wrote that the findings demonstrate that odor sensitivity can be increased by anxiety chemosignals. In addition, suggestions that there are different chemical composition of anxiety and neutral body odor samples were discovered. The authors believe that their research establishes the need for additional evaluation of the modulation of odor sensitivity by one’s own experienced emotion or by emotions experienced by others, as conveyed via chemosignals, and to further uncover the molecular basis of chemical communication of emotions in humans (1).

Woman suffering an anxiety attack. © Antonioguillem - stock.adobe.com

References

1. Wunder, A.; Bürkel, N.; Guder, I. et al. Enhanced Sensitivity to Odors Due to Chemosignals Associated with Anxiety. Commun. Chem. 2025, 8 (1), 129. DOI: 10.1038/s42004-025-01512-3

2. Loos, H. M.; Schaal, B.; Pause, B. M. et al. Past, Present, and Future of Human Chemical Communication Research. Perspect. Psychol. Sci. 2025, 20 (1), 20-44. DOI: 10.1177/17456916231188147

3. Lübke, K. T.; Pause, B. M. Always Follow Your Nose: The Functional Significance of Social Chemosignals in Human Reproduction and Survival. Horm. Behav. 2015, 68, 134-144. DOI: 10.1016/j.yhbeh.2014.10.001

4. de Groot, J. H.; Semin, G. R.; Smeets, M. A. On the Communicative Function of Body Odors. Perspect. Psychol Sci. 2017, 12 (2), 306-324. DOI: 10.1177/1745691616676599

5. Chen, D.; Katdare, A.; Lucas, N. Chemosignals of Fear Enhance Cognitive Performance in Humans. Chem. Senses 2006, 31 (5), 415-423. DOI: 10.1093/chemse/bjj046

6. Prehn, A.; Ohrt, A.; Sojka, B. et al. Chemosensory Anxiety Signals Augment the Startle Reflex in Humans. Neurosci, Lett. 2006, 394 (2), 127-130. DOI: 10.1016/j.neulet.2005.10.012

7. Prehn-Kristensen, A.; Wiesner, C.; Bergmann, T. O. et al. Induction of Empathy by the Smell of Anxiety. PLoS One 2009,4 (6), e5987. DOI: 10.1371/journal.pone.0005987

8. de Groot, J. H. B.; Smeets, M. A. M. Human Fear Chemosignaling: Evidence from a Meta-Analysis. Chem. Senses 2017, 42 (8), 663-673. DOI: 10.1093/chemse/bjx049