Fatigability and stress reactivity in patients with chronic fatigue syndrome versus healthy controls

Abstract

Introduction: Chronic fatigue syndrome (CFS) is a biopsychosocial disorder, with physical and cognitive fatigue and increased fatigability as core symptoms. This study evaluates fatigability and stress reactivity in patients with CFS and healthy controls (HC). Methods: Patients with CFS (n=31) and HC (n=24) performed the Maastricht Acute Stress Test (MAST - stress), the Paced Auditory Serial Attention Task (PASAT - mental fatigue), and an arm-leg cycling task (physical fatigue). Before, during and after the three tasks, participants rated subjective stress, intensity of mental fatigue and intensity of physical fatigue, respectively. In addition, data of the Checklist Individual Strength (CIS-20), a questionnaire measuring various aspects of fatigue retrospectively over the past, was collected. Results: Patients experienced more stress (main effect of group, p=0.0008), higher mental fatigability (group*time interaction effect, p=0.0368), and higher physical fatigability (group*time interaction effect, p<0.0001) and had a higher score on the CIS-20 questionnaire (p<0.0001) compared to HC. Additionally, patients’ fatigue recovered more slowly up to 24 hours after performing the cycling task (p<0.0001) and the PASAT (p=0.0077) compared to HC. Finally, the link between stress reactivity and fatigability was evaluated using mixed model analyses with AUCg, representing increase in stress scores during the MAST, as independent variable. Participants with a higher stress response experienced higher mental (p=0.0183) and physical fatigue (p=0.0312) during and after the PASAT and cycling task, respectively, and higher clinical daily life fatigue scores on the CIS-20 questionnaire (p=0.0029). Conclusion: In accordance with core CFS symptomatology, patients with CFS experience more physical and mental fatigability and they recover more slowly from physical and mental efforts than HC. Additionally, patients with CFS experience higher stress levels compared to controls during a validated stress task. Our results show that subjects who experience more stress, are also prone to experience more core CFS symptoms.