Autonomic nervous system dysfunctions in patients with stress-related and functional syndromes vs. healthy controls

Abstract

Background: It is hypothesized that a dysregulated autonomic nervous system is an important mechanism underlying stress-related disorders (SRD) and functional syndromes. The aim of our study was to examine ANS dysfunction by measuring heart rate, skin conductance, and skin temperature 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 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). Heart rate, skin conductance, and skin temperature were monitored continuously. Results: On average, heart rate (p = 0.003) and skin conductance levels (p < 0.001) were higher in FM/CFS and SRD patients compared to healthy controls at rest. Additionally, the average heart rate during rest was higher in FM/CFS compared to SRD (p = 0.032). There was a larger cardiac response to stress in both patient groups compared to HC (FM/CFS: p = 0.029, SRD: p = 0.003), while there was a smaller SC response to stress in FM/CFS patients compared to HC (p = 0.032), possibly due to a ceiling effect. ST could not differentiate between the different groups. Conclusion: Our results showed indications of a dominance of the sympathetic nervous system in patients compared to HC which was most pronounced in FM/CFS. This suggests the possibility of autonomic nervous system dysfunction as an underlying working mechanism for SRD and functional syndromes.