Autonomic nervous system dysfunctionalities in patients with stress-related and functional syndromes versus healthy controls

Abstract

Aims: It is hypothesized that a dysregulated autonomic nervous system (ANS) is an important mechanism underlying stress-related disorders (SRD) and functional syndromes. The aim of our study was to examine the physiology of the ANS by measuring heart rate (HR), skin conductance (SC), and peripheral skin temperature (ST) in response to and during recovery from psychosocial stressors in patients with SRD, fibromyalgia (FM)/chronic fatigue syndrome (CFS), and healthy controls (HC).

Methods: Patients with SRD (overstrain or burnout; n=59), FM/CFS (n=26) and HC (n=30) went through a standardized stress test consisting of a resting phase (120s), the STROOP color word task (120s), a recovery (120s), a mental arithmetic task (120s), a recovery (120s), a stress talk (120s) and a recovery (120s). HR, SC, and ST were monitored continuously.

Results: On average, HR and SC were higher in FM/CFS and SRD patients compared to healthy controls during the resting phase. Additionally, the average HR during rest was higher in FM/CFS compared to SRD. There was a larger SC response to stress in FM/CFS patients compared to HC, while there was a smaller increase in HR following a psychosocial stressor and drop in HR upon recovery in both patients groups compared to HC. ST could not differentiate between the different groups.

Conclusion: Our results indicate a dominance of the sympathetic nervous system in patients compared to HC which was most pronounced in FM/CFS. This suggests the possibility of ANS dysfunctionalities as one of the underlying working mechanisms for SRD and functional syndromes.