Can Depression Be Detected On Your Breath?
 
Dogs Detected "PTSD Molecules" On Breath
I read an article online today that said dogs had been successfully trained to detect signs of a PTSD (“post-traumatic stress disorder”) attack on a person’s breath. While that article didn’t cite the source research, I’ve found it here…
The experiment was set up such that 26 human volunteers breathed into face masks during 40 sessions when either not having a PTSD attack or when triggered to have an attack. Those masks were presented to the dogs who were then tested in ways that attempted to determine whether or not the dogs could recognise the specific scent of a PTSD attack. With 90% accuracy, they did.
Apparently the breath of people experiencing a PTSD flashback contains specific molecules such as cortisol from the HPA (hypothalamo-pituitary-adrenal) axis and adrenaline/noradrenaline from the SMA (sympathetico-adreno-medullary) axis.
As the author’s state…
“One dog’s performance correlated with the human donors’ self-reported fear responses and the other dog’s performance correlated with the human donors’ self-reported shame responses. Based on these correlations between dog performance and donor self-report measures, we speculate that the VOCs each dog was detecting likely originated from the sympathetico-adreno-medullary axis (SAM; adrenaline, noradrenaline) in the case of the first dog and the hypothalamo-pituitary-adrenal axis (HPA; glucocorticoids) in the case of the second dog.
Perhaps this research suggests the potential to have service dogs recognise signs of a PTSD attack and interrupt it by helping ground the person experiencing the flashback.
Can Depression Be Detected In Your Breath?
Having read that article, I wondered if the same could be true for depression. There’s currently no simple medical assay for depression. Generally, a person is diagnosed based on their answers to questions such as how are they feeling, sleeping, eating and coping with life in general.
Perhaps if dogs could be trained to recognise depression on the breath, then a machine such as a breathalyzer could do it too?
KOMUnews, CC BY 2.0Â via Wikimedia Commons
Perhaps a breathalyser could determine the severity of depression.
Perhaps several readings, taken over time, could show whether a particular method was working to help a person heal from depression.
I found a study published in 2022 in the same journal by a group from Germany, which looked at breath differences between people with depression and healthy controls…
In that study, changes were seen in the level of VOC’s (volatile organic compounds) between the depression patients and controls.
This is potentially very exciting because, as the authors’ state…
“there are currently no easy and frequently applicable non-invasive biomarkers available that could help to facilitate diagnosis of a depressive episode or that could guide to the most effective therapy”.
Other Illnesses With Specific Odours
This work with PTSD is claimed to be the first to show specificity for a PTSD attack, but dogs have also been shown to be able to sense:
Epileptic attacks:
“Our findings suggest that seizures are associated with an odour and that dogs detect this odour and demonstrate a marked increase in affiliative behaviour directed at their owners”
The Untrained Response of Pet Dogs to Human Epileptic Seizures
COVID infection:
“The highest performing dogs in the trial detected the odour of the virus in the samples with up to 94.3% sensitivity and up to 92% specificity, as published in the Journal of Travel Medicine”
COVID-19 Detection Dogs
Malaria infection:
“It is known that malaria mosquitoes prefer feeding on patients carrying malaria parasites. Further evidence suggests that this is an odour-mediated phenomenon: people infected with malaria smell more attractive to mosquitoes than those that are not infected. We have shown that dogs can detect this odour.”
Malaria Detection Dogs
… and even cancer:
“Many studies have been done to determine the accuracy canines have in detecting these VOCs produced by lung malignancies. In this review, we look at some of those prior studies that have shown this method of screening to be highly effective.”
Canine Scent Detection in Lung Cancer Screening
Implications for Depression
If dogs can sense all those different illnesses and conditions, and we can make a breathalyser which can report alcohol levels from breath, perhaps it’s possible to make a breathalyser device to rapidly diagnose these conditions, including depression, and potentially chart recovery from depression too.
