E2 ModerateModerate confidencePEM not requiredCross-SectionalPeer-reviewedMachine draft
A Concurrent Cognitive Task Does Not Perturb Quiet Standing in Fibromyalgia and Chronic Fatigue Syndrome.
Rasouli, Omid, Fors, Egil A, Vasseljen, Ottar et al. · Pain research & management · 2018 · DOI
Quick Summary
This study examined how well people with ME/CFS and fibromyalgia can balance while standing still, and whether doing mental math at the same time makes balancing harder. Researchers found that both ME/CFS and fibromyalgia patients had slightly worse balance control than healthy people, but surprisingly, adding a math task didn't make their balance worse—unlike what researchers expected.
Why It Matters
Understanding postural control deficits in ME/CFS is important for patient safety and quality of life. This study challenges the assumption that cognitive demands worsen motor control in these conditions, suggesting the underlying postural problems may be relatively fixed rather than dynamically sensitive to cognitive load—which has implications for rehabilitation approaches.
Observed Findings
- CFS patients displayed greater postural sway amplitude and ankle torque adjustments compared to healthy controls.
- Both CFS and FM groups showed lower frequency oscillations in postural sway compared to controls, suggesting slower balance correction mechanisms.
- Adding a concurrent arithmetic task did not significantly change postural control measures in any group.
- Fatigue severity correlated with postural control variables, whereas pain severity did not.
Inferred Conclusions
- ME/CFS and fibromyalgia are associated with fundamental postural control impairments that are independent of concurrent cognitive demands.
- The postural deficits observed appear to represent a baseline motor control alteration rather than a dynamic vulnerability to cognitive interference.
- Fatigue, not pain, is the primary symptom associated with postural control dysfunction in these conditions.
Remaining Questions
- Why do fatigue but not pain correlate with postural deficits, and what is the mechanistic relationship?
- Would dynamic or more complex balance tasks (e.g., perturbations, dual-task walking) reveal cognitive-motor interference that quiet standing does not?
- Are these postural abnormalities present at illness onset or acquired over time, and do they improve with treatment?
What This Study Does Not Prove
This cross-sectional study cannot establish causality or determine whether postural deficits develop before or after illness onset. The study does not prove that cognitive load never affects ME/CFS patients' balance in real-world scenarios; laboratory conditions may not capture complex, dynamic balance demands. The lack of cognitive task effect does not rule out central nervous system involvement in postural control deficits.
Tags
Symptom:Cognitive DysfunctionPainFatigue
Method Flag:Weak Case DefinitionExploratory Only
Metadata
- DOI
- 10.1155/2018/9014232
- PMID
- 30159106
- Review status
- Machine draft
- Evidence level
- Single-study or moderate support from human research
- Last updated
- 8 April 2026
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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