Physiological overreactivity and low end-tidal CO2 as a transdiagnostic stress response: Comparing between and within patients with stress-related bodily complaints versus healthy controls.

Abstract

Background: Although a dysregulated autonomic stress physiology is hypothesized to play a crucial role in the etiology and perpetuation of stress-related disorders, the respiratory system tends to be overlooked in the current literature.

Methods: The aim of our study was (1) to examine end-tidal CO2 concentration (PetCO2) in various patient groups experiencing stress-related bodily complaints in daily life [overstrain; n=35, burnout; n=44; and functional somatic syndrome (FSS); n=36], panic disorder (PD, n=36) and healthy controls (HC, n=30), and (2) to explore the triangular relationships between psychological variables (maladaptive perfectionism, experiential avoidance, and exposure to traumatic experiences), end-tidal CO2, and patient status. Participants filled out trait questionnaires and went through a baseline measurement of PetCO2 and two respiratory challenges with recovery whilst PetCO2 was continuously monitored by a capnograph.

Results: Our data showed lower PetCO2 in patients with stress-related disorders and PD compared to HC, suggesting physiological overreactivity as a transdiagnostic mechanism for both stress- and anxiety related disorders. This overreactivity was found to be partially mediated by exposure to traumatic experiences. Interestingly, a more passive action tendency was observed in the most chronic and severe stress-related disorders (FSS) compared to the more acute ones (overstrain).

Discussion: Taken together, our results are indicative for behavioral regulation to overrule metabolic regulation of the respiratory system in stress-related disorders.