The delayed fatigue effect in myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS)


By Megan A. Arrolla at al.


Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating, long-term condition characterised by extreme fatigue (worsened by exertion), muscle and joint pain, and sleep disturbance. Post-exertional fatigue has been demonstrated previously following physical exercise, but not from mental exertion alone.

Purpose: The aim of this exploratory study was to assess the ‘delayed fatigue effect,’ in this instance fatigue two days post-challenge, following a cognitively fatiguing task.

Methods: Thirty-two participants (23 women; mean age 44, SD = 11.24; mean illness duration nine years, SD = 7.32) completed the Cambridge Neuropsychological Test Automated Battery, which acted as the cognitive challenge. Self-report measures were also completed that assessed fatigue (Multidimensional Fatigue Inventory; MFI), and anxiety and depression (Hospital Anxiety and Depression Scale; HADS) pre- and two days post-testing.

Results: Significant differences were found between pre- and post-test measures in three MFI sub-scales of fatigue (general, mental, and physical) and on the depression scale of the HADS. However, there were no significant changes in motivation, activity level, or self-reported anxiety scores.

Conclusions: These findings are suggestive of post-exertional symptom exacerbation following mental effort. This may have implications for working environments that present cognitive demands to individuals with ME/CFS.

Source: Megan A. Arrolla, Elizabeth A. Attree, John M. O’Leary and Christine P. Dancey. Fatigue: Biomedicine, Health & Behavior. Volume 2, Issue 2, 2014.

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