Resting-state functional connectivity, cognition, and fatigue in response to cognitive exertion: a novel study in adolescents with chronic fatigue syndrome. — CFSMEATLAS
Resting-state functional connectivity, cognition, and fatigue in response to cognitive exertion: a novel study in adolescents with chronic fatigue syndrome.
Josev, Elisha K, Malpas, Charles B, Seal, Marc L et al. · Brain imaging and behavior · 2020 · DOI
Quick Summary
Researchers compared how the brains of teenagers with ME/CFS and healthy teenagers responded to a mentally demanding task using brain imaging. Both groups showed similar changes in brain activity and felt more tired after the mental effort. However, teenagers with ME/CFS started out more fatigued, performed worse on thinking tasks overall, and may have less energy available to draw from when their brain works hard.
Why It Matters
This is one of the few brain imaging studies examining ME/CFS in adolescents, an understudied population. Understanding whether ME/CFS involves different brain mechanisms—or rather a reduced capacity to access normal energy reserves—helps inform how cognitive exertion should be managed in young people and guides future research into the biological basis of the illness.
Observed Findings
Both CFS/ME and healthy adolescents showed reduced default mode network connectivity after cognitive exertion, indicating this is a normal brain response to mental effort.
Adolescents with ME/CFS had higher baseline subjective fatigue and performed worse on tests of processing speed, sustained attention, and learning compared to healthy controls.
Cognitive performance declined similarly in both groups after the mental task, including slower processing speed and reduced sustained attention.
Subjective fatigue increased in both groups following cognitive exertion at comparable rates.
No significant correlations were found linking changes in brain connectivity to changes in fatigue or cognitive performance over time.
Inferred Conclusions
ME/CFS may involve a lower threshold for accessing cognitive and energy resources rather than a fundamentally different brain response to cognitive demands.
Cognitive exertion appears to produce similar neurobiological fatigue mechanisms in both healthy adolescents and those with ME/CFS, suggesting the brain works similarly under stress.
The persistent baseline cognitive deficits and higher fatigue in the CFS/ME group suggest the condition affects overall cognitive capacity even before additional exertion occurs.
Remaining Questions
What causes the lower threshold for accessing cognitive resources in ME/CFS—is it mitochondrial dysfunction, metabolic differences, or another biological mechanism?
What This Study Does Not Prove
This study does not prove that cognitive exertion causes permanent brain damage or that the brain dysfunction observed is unique to ME/CFS. The cross-sectional design cannot establish causation, and the lack of brain-behavior correlations suggests the relationship between connectivity changes and fatigue/cognitive symptoms is more complex than currently understood. Small sample size limits generalizability.
Would longitudinal follow-up reveal whether repeated cognitive exertion worsens the condition in ME/CFS adolescents compared to controls?
Why were no correlations found between brain connectivity changes and fatigue/cognitive outcomes, and what other brain regions or measures might better explain these relationships?
Do these findings in adolescents generalize to adults with ME/CFS, and are there age-related differences in how the brain responds to cognitive demands?