Fatigue is associated with altered monitoring and preparation of physical effort in patients with chronic fatigue syndrome (2018) van der Meer et al

Hoopoe

Hoopoe

Senior Member (Voting Rights)
Is it just me or are they more honest about their views than usual?

Chronic fatigue syndrome (CFS) is characterized by disabling fatigue, which is suggested to be maintained by dysfunctional beliefs.
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CFS patients showed an effort-dependent behavioural bias towards less effort investment in response to directional feedback for the highest effort level as compared to HC. This bias was associated with reduced feedback-related activity in the DLPFC. These effects were proportional to state-related fatigue and prior beliefs about their ability to perform the task within CFS patients. CFS patients also showed higher activity in the supplementary motor area (SMA), proportional to their state-related fatigue, and reduced connectivity between SMA and sensorimotor cortex during motor preparation as compared to controls.
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I'm not 100% sure how to interpret this but it sounds like they may have shown that fatigued people put in less effort, and believe they are more limited in their activities. This is then interpreted as the beliefs causing the fatigue and limitation. I would be surprised if they properly excluded the ordinary interpretation that fatigue causes this belief and limitation.

https://www.sciencedirect.com/science/article/pii/S2451902218300430
 
CFS patients showed an effort-dependent behavioural bias towards less effort investment in response to directional feedback for the highest effort level as compared to HC.
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Swallowing a dictionary doesn't make it any cleverer.

strategist said:
it sounds like they may have shown that fatigued people put in less effort, and believe they are more limited in their activities. This is then interpreted as the beliefs causing the fatigue and limitation.
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Thank you.
 
No 'fatiguing' disease control group, this is useless... another study wasting money as its design does not allow to draw any conclusion about these specific differences being linked to CFS or to being sick, and certainly not a causalty link as they do.
 
I've only read the abstract. It looks like a worrying paper because it seems to give scientific validity to the 'false illness beliefs' nonsense by tying it to a test done with a machine and therefore supposedly objective. But it assumes the beliefs of the patients that they can't make more effort are false, rather than a realistic knowledge of the limitations imposed by their illness.
 
"Chronic fatigue syndrome (CFS) is characterized by disabling fatigue, which is suggested to be maintained by dysfunctional beliefs."

"suggested" - well put, the process of hypnotic suggestion comes to mind. "Look at my pendulum and slowly repeat after me: "I have dysfunctional beliefs, I have dysfunctional beliefs, I have…"
 
Wasn't there a study a few years back that actually tested if ME patients puts as much effort into trial/tasks as healthy controls.

They seemed to show that ME patients really were applying themselves and not faking.

I think it was an Australian study. Anyone remember?

Eta - had a quick look but cant find it
 
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Conclusions
These findings link fatigue symptoms to alterations in behavioural choices on effort investment, prefrontal functioning and SMA connectivity, with the DLPFC being associated with prior beliefs about physical abilities.
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But they do not say what causes what. The inference they want people to take away, is that lower effort investment is driven by the false illness belief. But from the abstract at least I don't think there is anything supporting that. They don't mention the other possibility of course, that the lower effort investment is sensibly applied to fit within physical limitations.
 
Invisible Woman said:
Wasn't there a study a few years back that actually tested if ME patients puts as much effort into trial/tasks as healthy controls.

They seemed to show that ME patients really were applying themselves and not faking.

I think it was an Australian study. Anyone remember?

Eta - had a quick look but cant find it
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There was this study from Australia:
J Clin Exp Neuropsychol. 2012;34(7):679-87. doi: 10.1080/13803395.2012.668176. Epub 2012 Mar 23.
Test effort in persons with Chronic Fatigue Syndrome when assessed using the Validity Indicator Profile.
Cockshell SJ1, Mathias JL.
Author information

Abstract
The current study examined the potential contribution of suboptimal effort to the cognitive deficits that are associated with Chronic Fatigue Syndrome (CFS) using the Validity Indicator Profile (VIP). Unlike most tests of effort, the VIP distinguishes between intentional and unintentional poor performance and does not assess cognitive functions that are affected by CFS, thereby reducing the risk of mistakenly attributing genuinely poor performance to reduced effort. The VIP was administered to 54 persons with CFS and 54 matched healthy community controls, and performance categorized into 1 of 4 response styles (valid: compliant; invalid: suppressed, irrelevant, inconsistent), based on the level of effort expended (high or low) and the intention to perform well or not. VIP performance was classified as valid for the majority of participants (CFS and controls), indicating high levels of effort and an intention to perform well. Three participants in the CFS group and four in the control group showed low levels of effort but an intention to do well (invalid: inconsistent). No participant performed in a manner indicative of an intent to perform poorly (invalid: suppressed, inconsistent). These findings suggest that poor effort is unlikely to contribute to cognitive test performance of persons with CFS.

PMID:

22440059

DOI:

10.1080/13803395.2012.668176
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Dolphin said:
There was this study from Australia:
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I don't have access to the full article, and might not get the answer to my question even if I did.

Can anyone tell me, without too much scientific complexity, how this study discriminated between sub-optimal effort due to physical effects, versus sub-optimal effort due to psychological effects.

I have sometimes thought that if you were to do a sort of "frogs legs electrical signal test" on a person in a suitably ethical way, could you then assess if the problem is in the muscles themselves or not, or in the signalling to the muscles. If it showed the problem was the muscles, then that would seem pretty cut and dried. If it showed a signalling problem, then there would still be much scope for a physical problem, but would cut down where to look. But I presume this sort of sanity check must already have been done.
 
Barry said:
I have sometimes thought that if you were to do a sort of "frogs legs electrical signal test" on a person in a suitably ethical way, could you then assess if the problem is in the muscles themselves or not, or in the signalling to the muscles. If it showed the problem was the muscles, then that would seem pretty cut and dried. If it showed a signalling problem, then there would still be much scope for a physical problem, but would cut down where to look. But I presume this sort of sanity check must already have been done.
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Julia Newton at Newcastle University has done that. She took muscle cultures from patients and controls then subjected them to continued electrical stimulation and measured the response. Unsurprisingly, there was significant differences between patients and controls.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122982
 
Cheesus said:
Julia Newton at Newcastle University has done that. She took muscle cultures from patients and controls then subjected them to continued electrical stimulation and measured the response. Unsurprisingly, there was significant differences between patients and controls.

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0122982
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I see this demonstrates muscle fatigue abnormalities compared to healthy controls. Do we know if there is anything similar that proves abnormalities against other fatigueing conditions? (I've only briefly skimmed this article).
 
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