Emotion Detectors
At baseline and during each cue exposure, donors reported their affect using the Positive and Negative Affect Schedule. Ivy’s performance correlated with the donors’ self-reported anxiety, and Callie’s performance correlated with the donors’ self-reported shame.
Based on these correlations, the researchers speculate Ivy detected VOCs that likely originated from the sympathetic-adrenomedullary axis, which involves adrenaline and noradrenaline.
VOCs detected by Callie likely originated in the hypothalamus-pituitary-adrenal axis, which involves cortisol and corticosterone. These two endocrine subsystems play a major role in reestablishing homeostasis in response to a stressor.
The results suggest some service dogs could alert to upcoming intrusion and hyperarousal symptoms even before physical signs manifest and before the person is even aware of the situation, said Ms. Kiiroja.
“This would enable earlier distraction and reminders to use skills learned in psychotherapy; this would have a better likelihood of increasing the efficacy of these skills and preventing further escalation of the arousal,” she said.
Most breath samples likely included both early and late stress VOCs, as the breath donors wore the trauma mask for a relatively long time, the authors noted. Future studies should test dogs’ olfactory acuity on samples collected minutes after the trauma cue, they added.
Another limitation is that all donors were regular cannabis users, so the results may not generalize to others. However, the fact the dogs demonstrated their detection ability even with cannabis users makes the proof-of-concept “more stringent,” Ms. Kiiroja said.
The goal of the study was to see if some dogs are capable of detecting stress VOCs from people with trauma histories in response to trauma cues, so the small number of dogs in the study isn’t a limitation, the authors noted.
‘Wonderful Work’
Commenting on the findings, Elspeth Ritchie, MD, chair of psychiatry, MedStar Washington Hospital Center, Washington, described the research as “wonderful work.” Dr. Ritchie, who was not a part of this study, has also studied PTSD supports dogs.
The study is yet another illustration of the “amazing things dogs can do ... not just for veterans but for people with mental illness.” They can be a source of comfort and help people manage their anxiety.
Training PTSD service dogs can be expensive, with some well-accredited organizations charging about $50,000 for an animal, Dr. Ritchie said. Training a dog to detect VOCs could also be costly, she added.
Although such research has increased in recent years, it’s unclear how it would be applied in practice. Identifying funding for this sort of study and designing trials would also be challenging, Dr. Ritchie added.
“The idea is good, but when you try to operationalize it, it gets tricky,” she said.
The fact that all donors in the study used cannabis is a confounding factor and raises the question of what else might confound the results, Dr. Ritchie added.
Dr. Ritchie emphasized that although ideally veterans would learn to recognize the onset of stress symptoms themselves, a dog could serve as a valuable companion in this process. “That’s precisely why this research should progress,” she said.
The authors and Dr. Ritchie reported no relevant disclosures.
A version of this article appeared on Medscape.com.