Stress differentially affects fatigue in women with depression or somatic symptom disorder

Abstract

Background: Fatigue is one of the most debilitating complaints in both depression and somatic symptom disorder. We examined whether subjective and physiological stress differentially affects fatigue in these two groups. Methods: 30 women with depression (DEPR) and 30 women with somatic symptom disorder (SSD) completed the Multidimensional Fatigue Inventory (MFI) and the Trier Inventory for Chronic Stress Screener (SSCS). Moreover, DEPR reported their momentary stress and fatigue during a period of 14 consecutive days at 5 time points each day. All participants also provided hair samples to determine cortisol levels (indicating long-term HPA axis activity). Data was analyzed using t-tests, regression analyses, and hierarchical linear models. Findings: DEPR had higher general and mental fatigue (MFI) as well as chronic stress levels (SSCS) than SSD (p<.001). Groups did not differ in their physical fatigue (MFI) or in hair cortisol levels (ps≥.114). Chronic stress predicted general and mental fatigue in SSD (ps≤.005), whereas it was associated with physical fatigue in DEPR (p=.018). Hair cortisol was not associated with chronic stress or fatigue in either sample (ps≥.170), nor with momentary fatigue or stress in DEPR (ps≥.654). In DEPR, momentary fatigue was positively associated with concurrent momentary stress (p<.001). Conclusion: Fatigue was associated with subjective, but not physiological chronic stress in both DEPR and SSD. Chronic stress predicted mental fatigue in SSD and physical fatigue in DEPR. Stress differentially affects fatigue in DEPR and SSD patients. Future research should elucidate the underlying mechanisms. Interventions should target stress and its effects on different fatigue dimensions.