The Smell of Stress and Fear

Can we recognize if people around us are stressed, anxious or fearful without observing their facial expressions, body language and actions or hearing their voice and messages? Can we understand if we are stressed ourselves without assessing our heart rate, blood pressure, noticing dry throat, sweating, drops or surges in energy? Yes, we can - by using our nose - as humans, too, recognize and transmit their emotions through chemical senses.

When we are stressed or panic we become more sensitive to odors (Buróna et al., 2015), ranking neutral odors as unpleasant (Krusemark et al, 2013). Chronic stress will actually dull the senses (Yuan & Slotnick, 2013), but that's another story.

When other people are stressed, we can feel it without seeing or hearing them. Numerous experiments showed that we can recognize emotions from sweat alone. We might not be able to tell why, but experience sympathy by smelling odors of those taking exams vs just exercising on a bike (Prehn-Kristensen et al 2009), become more cooperative when smelling hard work, more submissive when detecting that other people's health status prioritizes their needs, more fearful when detecting chemical clues coming from people watching horror movies (Zhou and Chen, 2009, de Groot et al., 2012) and exhibit risk taking behavior when detecting other people's anxieties (Haegler et al, 2010).

What is the exact chemistry of stress, anxiety and fear? We are getting close to deciphering it. Stress, for example, might be recognized by six biomarkers, including indole and 2-methyl-pentadecane (Turner et al, 2013) that are also indicators of COPD (Martinez-Lozano Sinues et al, 2014) and heart disease. 

Correlating chemicals to health and wellness conditions is not easy. Acetone in breath, for example, has attracted the interest of clinical researchers for more than 60 years. Several dozen independent studies using various techniques and methods showed that much more complex analysis is required with long-term measurements of various health and environmental indicators including diet, treatments and prior medical history (Dowlaty, Yoon, and Galassetti, 2013). Aurametrix provides an integrated platform for such analysis, but until we sift through all the data, if you are stressed out, just take a deep breath and relax. Inhale confidence, exhale doubt.

REFERENCES

Haegler, K., Zernecke, R., Kleemann, A., Albrecht, J., Pollatos, O., Brückmann, H., & Wiesmann, M. (2010). No fear no risk! Human risk behavior is affected by chemosensory anxiety signals Neuropsychologia, 48 (13), 3901-3908 DOI: 10.1016/j.neuropsychologia.2010.09.019

Prehn-Kristensen A, Wiesner C, Bergmann TO, Wolff S, Jansen O, Mehdorn HM, Ferstl R, & Pause BM (2009). Induction of empathy by the smell of anxiety. PloS one, 4 (6) PMID: 19551135

Dowlaty N, Yoon A, & Galassetti P (2013). Monitoring states of altered carbohydrate metabolism via breath analysis: are times ripe for transition from potential to reality? Current opinion in clinical nutrition and metabolic care, 16 (4), 466-72 PMID: 23739629

de Groot JH, Smeets MA, Kaldewaij A, Duijndam MJ, & Semin GR (2012). Chemosignals communicate human emotions. Psychological science, 23 (11), 1417-24 PMID: 23019141

Krusemark EA, Novak L, Gitelman D, Li W. (2013) When the sense of smell meets emotion: Anxiety-state-dependent olfactory processing and neural circuitry adaptation. Journal of Neuroscience. 33(39):15324 –15332.

Martinez-Lozano Sinues P, Meier L, Berchtold C, Ivanov M, Sievi N, Camen G, Kohler M, Zenobi R Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland. Respiration; International Review of Thoracic Diseases [2014, 87(4):301-310] PMID: 25545545

Yuan TF, Slotnick BM. Roles of olfactory system dysfunction in depression. (2014) Prog Neuropsychopharmacol Biol Psychiatry. 54:26-30. doi: 10.1016/j.pnpbp.2014.05.013.