Ambulatory Detection of Volatile Organic Compounds (VOCs) Associated with Depression

Background: Depression has been associated with dysbiosis and transit disturbances. Objective: We investigated whether a new ambulatory device (X-PID 8500®) may detect a specific gas associated with depression. Methods: A retrospective analysis of data collected during routine consultations for Small Intestinal Bowel Overgrowth. Results: 117 patients were included. 48 patients presented with a peak between 92 and 97 seconds (m-xylene peak). 69 patients did not exhale VOCs detectable within this range. 32 patients had a recent medical history of depression. 22 of them presented with m-xylene peak whereas the 10 remaining patients did not (45.8% versus 14.5%; p<0.001). 8 patients presented with ulcerative colitis: 7 of them presented with m-xylene peak (p<0.001). 8 patients have a medical history of severe acne treated with isotretinoin. Only two of them exhaled m-xylene (p<0.001). Constipation was more frequent in patients with depression (19.4% versus 11.8%; p<0.01) and was not associated with m-xylene. Two different mechanisms are possible and are discussed. The probability to find m-xylene peak in a non-depressive patient remains high. However, such a peak may precede a depressive decompensation. Further investigations and follow-up are required to clarify this issue. Conclusion: X-PID 8500® can detect VOCs associated with a subgroup of depression in clinical ambulatory practice.