Breath gas analysis in major depressive disorder
Breath signatures in depression:
Stress-related changes in the exhalation signal during the early phase of disease management
The following project is part of our research in the field of breath gas analysis.
Project description
About one-third of patients with major depressive disorder (MDD) do not respond to at least two different therapies with antidepressants. These patients need other treatment options as early as possible. Unfortunately, there are currently no non-invasive, easy-to-use and frequently applicable biomarkers that could facilitate the diagnosis of unipolar depressive disorder (MDD) or support decision-making in the selection of therapies. Since the lungs act as a gas exchanger between the internal and external environment, the effects of MDD could easily be assessed by analysing exhaled breath. Such methods are already successfully used in alcohol testing and diabetes mellitus. In a pilot study of 25 patients with MDD and 25 healthy subjects, we were able to find markers that differ significantly between the groups and that resulted in a good classification with an accuracy of over 80% in test and validation samples. The aim of the study is to identify signatures in exhaled air that distinguish a depressive episode in MDD from a healthy state. In addition, the study will examine which factors (treatment, nutrition, environment) influence these signatures, whether the identified signatures can provide information on the course of the disease, and whether they show parallels to the dysregulation of the cortisol response during waking, which has been shown in depression. A test sample of 80 patients with MDD according to DSM-V (40 of whom are currently free of antidepressant medication and 40 of whom are undergoing antidepressant treatment) and 80 healthy subjects will be included. Furthermore, a confirmation sample of 40 patients with MDD (20 currently free of antidepressant medication and 20 with ongoing antidepressant treatment) and 40 healthy subjects will be recruited. The clinical examinations and breath measurements will be repeated after 14 and 28 days. The analysis of the breath is carried out by proton transfer reaction mass spectrometry (PTR-TOF-MS). In addition, the underlying substances are determined using GC-GC-TOF-MS. The ambient conditions and the collection method using ‘Tedlar’ bags are controlled. The aim is to develop a marker that could support the diagnosis of depression, although this would then have to be shown in a clinical biomarker study.
Content of the DFG project page
The project is funded by the DFG (German Research Foundation) from 03/2021 to 09/2025.
