Researchers have found that exposure to human odours, specifically extracted from sweat, could potentially enhance treatment for certain mental health issues.

In an initial study, they discovered that social anxiety diminished in patients undergoing mindfulness therapy while exposed to human “chemo-signals” or body odour derived from volunteers’ underarm sweat.

Elisa Vigna, the lead researcher from the Karolinska Institute in Stockholm, presented the pilot study’s findings at the European Congress of Psychiatry in Paris.

Vigna said: “Our state of mind causes us to produce molecules (or chemo-signals) in sweat which communicate our emotional state and produce corresponding responses in the receivers. The results of our preliminary study show that combining these chemo-signals with mindfulness therapy seems to produce better results in treating social anxiety than can be achieved by mindfulness therapy alone”.

Social anxiety disorder is a prevalent mental health condition that causes excessive worry about engaging in social situations, affecting daily activities and interactions. The study collected sweat from volunteers and exposed patients to chemo-signals extracted from the samples during social anxiety treatment. Sweat samples were taken from volunteers who watched short, emotion-inducing movie clips. The study then involved 48 women with social anxiety, divided into three groups of 16, who underwent mindfulness therapy while exposed to different odours or clean air as a control.

Vigna explained: “We found that the women in the group exposed to sweat from people who had been watching funny or fearful movies, responded better to mindfulness therapy than those who hadn’t been exposed. We were a little surprised to find that the emotional state of the person producing the sweat didn’t differ in treatment outcomes – sweat produced while someone was happy had the same effect as someone who had been scared by a movie clip. So there may be something about human chemo-signals in sweat generally which affects the response to treatment.”

The follow-up study will test if exposure to human presence causes this effect, using sweat from individuals watching emotionally neutral documentaries. Vigna continued: “We found that individuals who undertook one treatment session of mindfulness therapy together with being exposed to human body odours showed about 39% reduction in anxiety scores). For comparison, in the group receiving only mindfulness (the control group), we saw a 17% reduction in anxiety scores after one treatment session.

This proof-of-concept study’s results are considered preliminary, and a larger study is planned to confirm the findings. The researchers, in collaboration with the University of Pisa, are analyzing over 300 separate compounds in human sweat to identify and isolate the molecules responsible for the observed effects. This research is part of the EU-funded Horizon2020 project POTION (“Promoting Social Interaction through Emotional Body Odors”) 4.

Dr Julian Beezhold, Secretary General of the European Psychiatric Association, welcomed the study but emphasized the need for independent replication of the findings. Dr Beezhold was not involved in the study. The European Congress of Psychiatry took place from 25th-28th March 2023, in Paris.