Modulatory effects of cognitive exertion on regional functional connectivity of the salience network in women with ME/CFS: A pilot study.
Manca, Riccardo, Khan, Katija, Mitolo, Micaela et al. · Journal of the neurological sciences · 2021 · DOI
Quick Summary
This study looked at how the brain responds to mental effort in women with ME/CFS compared to healthy women. Researchers used brain imaging to examine specific networks involved in attention and awareness before and after a cognitive task. Women with ME/CFS experienced increased fatigue and pain after the mental exertion, while a particular brain region (the insula) showed stronger connections to areas controlling reward and decision-making—changes that matched worsening symptoms.
Why It Matters
Post-exertional malaise (PEM) is a hallmark and debilitating feature of ME/CFS with poorly understood neurobiological mechanisms. This study provides preliminary evidence that cognitive exertion triggers specific brain network abnormalities linked to symptom worsening, potentially opening new avenues for understanding the neurobiology of PEM and identifying therapeutic targets.
Observed Findings
Cognitive exertion induced significant increases in fatigue and pain symptoms in ME/CFS patients compared to controls, with no changes in objective cognitive performance in either group.
Patients with ME/CFS showed baseline alterations in functional connectivity of the default-mode network compared to controls, particularly between frontal areas and other DMN seeds.
Following cognitive exertion, patients (but not controls) demonstrated significantly greater functional connectivity increases between the right insula and frontal and subcortical regions.
These insula-related functional connectivity increases were significantly correlated with worsening of fatigue and pain symptoms in ME/CFS patients.
Inferred Conclusions
Cognitive exertion can trigger post-exertional malaise symptoms in women with ME/CFS through alterations in salience network functional connectivity.
Enhanced connectivity between the right insula and regions involved in reward processing and cognitive control may represent a neural signature of symptom exacerbation in response to cognitive demand.
The salience network, particularly the insula, appears to play a key role in the neurobiological mechanisms underlying PEM in ME/CFS.
Remaining Questions
Would similar patterns of brain connectivity changes and symptom exacerbation be observed in men with ME/CFS or across different ME/CFS symptom presentations?
What This Study Does Not Prove
This pilot study does not prove that insula hyperconnectivity causes PEM or that it is specific to ME/CFS—the small sample size (6 patients) and observational design prevent causal claims. It does not establish whether these brain changes occur before, during, or after symptom worsening, nor does it confirm whether similar patterns would be found in men or across diverse ME/CFS presentations. Correlation between FC changes and symptom reports does not establish mechanism.
What is the temporal relationship between insula connectivity changes and symptom onset—do these brain changes precede, accompany, or follow symptom worsening?
Do other types of exertion (physical, orthostatic) produce similar or distinct patterns of functional connectivity disruption compared to cognitive exertion?
Could targeted interventions that modulate salience network function reduce post-exertional symptom severity in ME/CFS patients?