Resting-state functional connectivity, cognition, and fatigue in response to cognitive exertion: a novel study in adolescents with CFS (2019) Josev

Cheshire

Cheshire

Senior Member (Voting Rights)
Emerging evidence suggests that central nervous system dysfunction may underlie the core symptoms of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) in adults, such as cognitive disturbance, fatigue and post-exertional malaise.

Research into brain dysfunction in the pediatric CFS/ME context, however, is severely lacking. It is unclear whether the adolescent CFS/ME brain functions differently compared with healthy peers, particularly in situations where significant mental effort is required.

This study used resting-state functional MRI in a novel repeated-measures design to evaluate intrinsic connectivity, cognitive function, and subjective fatigue, before and after a period of cognitive exertion in 48 adolescents (25 CFS/ME, 23 healthy controls).

Results revealed little evidence for a differential effect of cognitive exertion in CFS/ME compared with controls. Both groups demonstrated a similar rate of reduced intrinsic functional connectivity within the default mode network (DMN), reduced sustained attentional performance, slower processing speed, and increased subjective fatigue as a result of cognitive exertion.

However, CFS/ME adolescents consistently displayed higher subjective fatigue, and controls outperformed the CFS/ME group overall on cognitive measures of processing speed, sustained attention and new learning. No brain-behavior relationships were observed between DMN connectivity, cognitive function, and fatigue over time.

These findings suggest that effortful cognitive tasks may elicit similar levels of energy expenditure across all individuals in the form of reduced brain functioning and associated fatigue. However, CFS/ME may confer a lower starting threshold from which to access energy reserves and cognitive resources when cognitive effort is required.
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https://link.springer.com/article/10.1007/s11682-019-00119-2
 
Trying to summarise the abstract for a news item, does this make sense?

Functional MRI showed similar changes after cognitive exertion in CFS patients and controls, suggesting similar effort and energy expenditure, but CFS patients were more fatigued and did less well on tests of speed and sustained attention and new learning. , suggesting lower starting energy threshold and cognitive resources.

Edited to remove authors speculative conclusions.
 
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Trish said:
Trying to summarise the abstract for a news item, does this make sense?

Functional MRI showed similar changes after cognitive exertion in ME and controls, suggesting similar effort and energy expenditure, but CFS patients were more fatigued and did less well on tests of speed and sustained attention, suggesting lower starting energy threshold and cognitive resources.
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Perhaps tangentially supporting the glucose problem. If your glucose energy production system is screwed, would lack of starting energy not be a given ?
 
That tweet from Dr Mark Guthridge is a bit misleading, as cognitive exertion in the controls also resulted in reduced processing speed and attention - i.e. the same as with the young people with ME/CFS. It's just that the young people with ME/CFS were starting from a lower baseline.
Both groups demonstrated a similar rate of reduced intrinsic functional connectivity within the default mode network (DMN), reduced sustained attentional performance, slower processing speed, and increased subjective fatigue as a result of cognitive exertion.
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This was interesting:
This would suggest that future application of rs-fMRI analysis as a tool for identifying diagnostic biomarkers of pediatric CFS/ME appears limited.
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And this, where it seems likely that the young people with ME/CFS don't need advice on sleep hygiene to fix their sleep quality problems.
Interestingly, CFS/ME adolescents reported significantly lower levels of subjective sleep quality than healthy adolescents on the ASWS, despite similar sleep hygiene levels on the ASHS.
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I have always felt uneasy about the term "subjective fatigue" in this sort of context. It seems to leave the way open to all sorts of misunderstanding. Presumably what it means is that the ME patients report greater levels of fatigue when there is no objectively measurable, or, at least, measured difference. It always seems to suggest the possibility that the reporting or the perception are faulty, and not the means of measurement. Perhaps it is too nice a distinction.
 
If I read it correctly, one good thing from this is the MRI confirms that the pwME were making just as much effort - as showed in the brain activity, but despite this their speed, sustained attention and memory were functioning less well on the tests. So it's not about not trying hard enough, being lazy, malingering etc. It seems to be about a reduced capacity, not reduced effort.
 
Trish said:
Functional MRI showed similar changes after cognitive exertion in ME and controls, suggesting similar effort and energy expenditure, but CFS patients were more fatigued and did less well on tests of speed and sustained attention, suggesting lower starting energy threshold and cognitive resources.
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Trish said:
If I read it correctly, one good thing from this is the MRI confirms that the pwME were making just as much effort - as showed in the brain activity
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Sadly, I don't think their comments about effort and energy mean anything scientific. There is nothing about energy expenditure in the study as far as I am aware. I think their final statement in the abstract is hot air. The real finding of the study is that the ME patients' scans were normal - which is important.
 
Trish said:
Do you think there is any way of explaining the ME patients doing less well on the tests (speed, sustained attention etc), given that their brain scans indicated equivalent effort?
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Only that they have ME and we don't know why that impairs thinking. I don't think the scan show effort. I am not sure anybody knows what they show other than pretty patterns.
 
Haven't they done studies with MRI's that showed a lack of blood flow for ppl with depression?
 
Jonathan Edwards said:
Sadly, I don't think their comments about effort and energy mean anything scientific.
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I think they measured fatigue with a visual analogue scale before and after the cognitive tasks. ME/CFS patients had more fatigue at each timepoint but the increase in fatigue following cognitive challenges was the same in controls. So the cognitive tasks did not increase fatigue more in the patients than in controls. I think this is what the term energy expenditure refers to.
 
Trish said:
If I read it correctly, one good thing from this is the MRI confirms that the pwME were making just as much effort - as showed in the brain activity, but despite this their speed, sustained attention and memory were functioning less well on the tests.
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Thats an interesting thought, but if I understood correctly the authors do not argue that the similar MRI scans are an indication of similar effort. Or did I miss something?
 
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SPECT scans might be useful but they are frowned upon in my neck of the wood (medically speaking), probably because they show something amiss on a fairly reliable basis.
 
Michiel Tack said:
Thats an interesting thought, but if I understood correctly the authors do not argue that the similar MRI scans are an indication of similar effort. Or did I miss something?
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Probably me over interpreting the authors' interpretation:
These findings suggest that effortful cognitive tasks may elicit similar levels of energy expenditure across all individuals in the form of reduced brain functioning and associated fatigue.
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I took that to mean they were seeing on the brain scans evidence of similar levels of effortful energy expenditure, ie trying just as hard.
 
If their MRI's aren't up to the task of demonstrating WHERE the cognitive deficits arise, then either the technology isn't up to snuff, or they haven't learned yet how to see and correctly interpret what it does show. We well know what blunt tools neurocognitive tests are, and how they routinely fail at capturing deficits withing our and similar communities. Brain imaging often isn't far removed from those, at least in terms of actually capturing - and demonstrating that concretely - what they hope/believe they are. Yet we are told that the problem is only a misplaced belief that there is a problem.

I cannot understand why patients pretend that neurologists and/or psychs, and the radiologists who they employ to read tea leaves, actually know what they are talking about even half of the time.
 
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Write up from ME Research UK on this study
Comment by ME Research UK
Cognitive symptoms are very common in ME/CFS, and can be some of the most frustrating problems affecting the daily lives of people with the illness. Since cognitive function is what enables us gather and process information, abnormalities will have a significant impact on our ability to function at home, work, or school.

Often collectively referred to as ‘brain fog’, cognitive symptoms include difficulties with memory, concentration, and the sorting of information. These elements have been measured objectively in ME/CFS patients, including in studies supported by ME Research UK, such as the work of Prof. Jo Nijs and his group in Belgium.
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http://www.meresearch.org.uk/our-research/completed-studies/functional-connectivity-in-adolescents/
 
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