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Cognitive Functioning in People With CFS: A Comparison Between Subjective and Objective Measures

Bob

Senior Member
Messages
16,455
Location
England (south coast)
Cognitive Functioning in People With Chronic Fatigue Syndrome: A Comparison Between Subjective and Objective Measures.
Cockshell SJ, Mathias JL.
Neuropsychology. 2013 Dec 23. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/24364389/?ncbi_mmode=std

Abstract
Objective: The purpose of this study was to examine the relationship between subjective and objective assessments of memory and attention in people with chronic fatigue syndrome (CFS), using tests that have previously detected deficits in CFS samples and measures of potential confounds. Method: Fifty people with CFS and 50 healthy controls were compared on subjective (memory and attention symptom severity, Cognitive Failures Questionnaire, Everyday Attention Questionnaires) and objective (California Verbal Learning Test, Rey-Osterreith Complex Figure Test, Paced Auditory Serial Addition Test, Stroop task) measures of memory and attention. Fatigue, sleep, depression, and anxiety were also assessed. Results: The CFS group reported experiencing more cognitive problems than the controls, but the two groups did not differ on the cognitive tests. Scores on the subjective and objective measures were not correlated in either group. Depression was positively correlated with increased severity of cognitive problems in both the CFS and control groups. Conclusions: There is little evidence for a relationship between subjective and objective measures of cognitive functioning for both people with CFS and healthy controls, which suggests that they may be capturing different constructs. Problems with memory and attention in everyday life are a significant part of CFS. Depression appears to be related to subjective problems but does not fully explain them. (PsycINFO Database Record (c) 2013 APA, all rights reserved).
 

MeSci

ME/CFS since 1995; activity level 6?
Messages
8,231
Location
Cornwall, UK
Cognitive Functioning in People With Chronic Fatigue Syndrome: A Comparison Between Subjective and Objective Measures.
Cockshell SJ, Mathias JL.
Neuropsychology. 2013 Dec 23. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/24364389/?ncbi_mmode=std

Abstract
Objective: The purpose of this study was to examine the relationship between subjective and objective assessments of memory and attention in people with chronic fatigue syndrome (CFS), using tests that have previously detected deficits in CFS samples and measures of potential confounds. Method: Fifty people with CFS and 50 healthy controls were compared on subjective (memory and attention symptom severity, Cognitive Failures Questionnaire, Everyday Attention Questionnaires) and objective (California Verbal Learning Test, Rey-Osterreith Complex Figure Test, Paced Auditory Serial Addition Test, Stroop task) measures of memory and attention. Fatigue, sleep, depression, and anxiety were also assessed. Results: The CFS group reported experiencing more cognitive problems than the controls, but the two groups did not differ on the cognitive tests. Scores on the subjective and objective measures were not correlated in either group. Depression was positively correlated with increased severity of cognitive problems in both the CFS and control groups. Conclusions: There is little evidence for a relationship between subjective and objective measures of cognitive functioning for both people with CFS and healthy controls, which suggests that they may be capturing different constructs. Problems with memory and attention in everyday life are a significant part of CFS. Depression appears to be related to subjective problems but does not fully explain them. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

It would be good to see the full paper to see for example how the people with CFS were diagnosed, and other selection criteria. At least the authors acknowledge that
Problems with memory and attention in everyday life are a significant part of CFS.

I wonder what these 'different constructs' are that they refer to.
 

Bob

Senior Member
Messages
16,455
Location
England (south coast)
It would be good to see the full paper...
Yes, agreed. From the abstract wording, it doesn't look like they set out to disprove that ME patient have objectively measured cognitive dysfunction. It's a single paper, so it doesn't mean much on it's own, but it would be interesting to read it.
It seems that they haven't attempted to measure post-exertional cognitive dysfunction.

The authors published this paper, earlier in the year, with different conclusions:
Cognitive deficits in chronic fatigue syndrome and their relationship to psychological status, symptomatology, and everyday functioning.
Neuropsychology. 2013 Mar;27(2):230-42. doi: 10.1037/a0032084.
Cockshell SJ, Mathias JL.
http://www.ncbi.nlm.nih.gov/pubmed/23527651

Abstract
OBJECTIVE:
To examine cognitive deficits in people with chronic fatigue syndrome (CFS) and their relationship to psychological status, CFS symptoms, and everyday functioning.

METHOD:
The current study compared the cognitive performance (reaction time, attention, memory, motor functioning, verbal abilities, and visuospatial abilities) of a sample with CFS (n = 50) with that of a sample of healthy controls (n = 50), all of whom had demonstrated high levels of effort and an intention to perform well, and examined the extent to which psychological status, CFS symptoms, and everyday functioning were related to cognitive performance.

RESULTS:
The CFS group showed impaired information processing speed (reaction time), relative to the controls, but comparable performance on tests of attention, memory, motor functioning, verbal ability, and visuospatial ability. Moreover, information processing speed was not related to psychiatric status, depression, anxiety, the number or severity of CFS symptoms, fatigue, sleep quality, or everyday functioning.

CONCLUSION:
A slowing in information processing speed appears to be the main cognitive deficit seen in persons with CFS whose performance on effort tests is not compromised. Importantly, this slowing does not appear to be the consequence of other CFS-related variables, such as depression and fatigue, or motor speed.

If I recall correctly some studies have shown that only certain aspects of cognition are dysfunctional, such as processing speed, as in the above and below papers, and perhaps only for complex tasks (multi-tasking?) as the below paper shows. So I wonder if this latest study repeated the same tests, to assess processing speed for complex tasks.

Here's a recent paper that shows that processing speed is a problem for complex tasks:

Attention network test: Assessment of cognitive function in chronic fatigue syndrome.
Togo F, Lange G, Natelson BH, Quigley KS.
J Neuropsychol. 2013 Sep 24. doi: 10.1111/jnp.12030. [Epub ahead of print]
http://onlinelibrary.wiley.com/doi/10.1111/jnp.12030/abstract

Abstract
Information processing difficulties are common in patients with chronic fatigue syndrome (CFS). It has been shown that the time it takes to process a complex cognitive task, rather than error rate, may be the critical variable underlying CFS patients' cognitive complaints. The Attention Network Task (ANT) developed by Fan and colleagues may be of clinical utility to assess cognitive function in CFS, because it allows for simultaneous assessmentof mental response speed, also called information processing speed, and error rate under three conditions challenging the attention system. Comparison of data from two groups of CFS patients (those with and without comorbid major depressive disorder; n = 19 and 22, respectively) to controls (n = 29) consistently showed that error rates did not differ among groups across conditions, but speed of information processing did. Processing time was prolonged in both CFS groups and most significantly affected in response to the most complex task conditions. For simpler tasks, processing time was only prolonged in CFS participants with depression. The data suggest that the ANT may be a task that could be used clinically to assess information processing deficits in individuals with CFS.

© 2013 The British Psychological Society.



Here's quite a comprehensive 2013 review of cognitive deficits in ME/CFS patients, but Lenny Jason and others (I haven't read it in full yet):

Cognitive impairments associated with CFS and POTS
Lindzi Shanks, Leonard A. Jason, Meredyth Evans, and Abigail Brown
Front Physiol. 2013; 4: 113.
Published online 2013 May 16. doi: 10.3389/fphys.2013.00113
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3655280/
 
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wdb

Senior Member
Messages
1,392
Location
London
The CFS group reported experiencing more cognitive problems than the controls, but the two groups did not differ on the cognitive tests. Scores on the subjective and objective measures were not correlated in either group.

So if I'm interpreting this right the good news is that yet again subjective measures have been shown to be 100% worthless as a measure of incapacity. The bad news is this might be taken to demonstrate CFS patients subjectively overestimate the severity of their cognitive impairments. I think a more likely explanation might be that like physical impairments stamina is the issue so a relatively short cognitive test might not be sufficient to differentiate between the groups.
 

MeSci

ME/CFS since 1995; activity level 6?
Messages
8,231
Location
Cornwall, UK
So if I'm interpreting this right the good news is that yet again subjective measures have been shown to be 100% worthless as a measure of incapacity. The bad news is this might be taken to demonstrate CFS patients subjectively overestimate the severity of their cognitive impairments. I think a more likely explanation might be that like physical impairments stamina is the issue so a relatively short cognitive test might not be sufficient to differentiate between the groups.

I agree. Personally I find that my cognitive function varies in a similar way to physical function. Some days it is really good and barely slowed at all. On bad days it's not just slowness but an almost complete inability to think. What causes both physical and cognitive fatigue for me is almost entirely PEM and/or the wrong food.
 

Bob

Senior Member
Messages
16,455
Location
England (south coast)
I think a more likely explanation might be that like physical impairments stamina is the issue so a relatively short cognitive test might not be sufficient to differentiate between the groups.
Also, some studies have shown that speed of processing in complex tasks is abnormal, whereas all other cognitive tasks have been assessed to be normal. So it would be interesting to see if they tested this specific issue in the latest study.

Also, did they plot cognition vs effort? Perhaps if ME patients apply extraordinary effort to their cognitive tasks then the cognitive deficits are not so obvious, when objectively measured. But they are obvious subjectively, because of both the extra effort needed to get results, and also because of the pay-back and extra exhaustion experienced afterwards.
 
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Sean

Senior Member
Messages
7,378
At least these issues are starting to be explicitly discussed in the peer reviewed literature. An important step forward, albeit long overdue, and with many more left to take.

But it is a start.
 

Bob

Senior Member
Messages
16,455
Location
England (south coast)
Beth Unger is testing for post-exertional cognitive deficits (using online tests) in the large CDC study, for 48 hours after the one-day exercise test. But I don't know if they are testing for processing speed during complex tasks. Probably not, knowing the CDC.
 

Snow Leopard

Hibernating
Messages
5,902
Location
South Australia
Studies like this can be biased in that patients of above average intelligence are significantly more likely to participate.

So the results can be a result of apples vs oranges.

The other issue is that of fatigablity. A short battery of tests won't reveal the same differences as if you expected patients to do 8 hours of tests in one day. The difficulty is that if you ask patients to do that, many will decline, which is why studies like this are easily biased.
 

MeSci

ME/CFS since 1995; activity level 6?
Messages
8,231
Location
Cornwall, UK
Was this different to this study?
http://www.ncbi.nlm.nih.gov/pubmed/23527651

Same number of patients and controls, but they found :

Different study, same authors. I wonder which kinds of memory they tested? There is short-term, long-term, procedural, etc. Different conditions (e.g. types of dementia) affect different types of memory at different stages, IIRC, so it's important to be specific when reporting research findings.
 

SOC

Senior Member
Messages
7,849
If I'm reading the title of this paper correctly and assuming that they titled their paper appropriately (Cognitive Functioning in People With Chronic Fatigue Syndrome: A Comparison Between Subjective and Objective Measures), this study was not about us, but about the efficacy of subjective vs objective tests. The authors clearly understand that we have cognitive problems (impaired processing speed, in particular) based on their earlier publication.

So isn't the point of this paper that subjective tests of cognitive dysfunction suck raw eggs?
 
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Simon

Senior Member
Messages
3,789
Location
Monmouth, UK
Brief commentary on the abstract

I blogged about Susan Cockshell's impressive earlier work, 'Brain fog: The Research' which includes a meta-analysis (covering 1,500 CFS patients)
This study said:
Conclusions: There is little evidence for a relationship between subjective and objective measures of cognitive functioning for both people with CFS and healthy controls, which suggests that they may be capturing different constructs.
I think those are two important conclusions.

So isn't the point of this paper that subjective tests of cognitive dysfunction suck raw eggs? [assuming you do mean subjective not objective here]
So if I'm interpreting this right the good news is that yet again subjective measures have been shown to be 100% worthless as a measure of incapacity.
I think it's more complex that that. Lab tests of cognitive functioning are very narrow and very artificial.

Take the example of the Stroop test, used in this study and one of the most common cognitive function tests there is. The simplest way to see how it works is just to look at the two lists below.
Don’t read them, instead say out loud the color each word is displayed in, as quickly as you can.

stroop1.jpg

Not so easy… (Try it online)

Exactly how the Stroop test relates to real-world functioning isn't clear - and that's what the authors mean when they say:
There is little evidence for a relationship between subjective and objective measures of cognitive functioning for both people with CFS and healthy controls, which suggests that they may be capturing different constructs

On top of the relevance of the test there are 2 other issues.
  • Fatigability as @Snow Leopard says where you may need repeated testing to reveal problems
  • Stress testing, as @Bob mentioned
A fMRI brain study found that CFS patients perform as well as controls but activate more brain regions in the process, ie working harder to get the same result. Repeat tests may well find a difference emerge over time (there were hints of this in Susan Cockshell's earlier work)

In my view, stress testing could well be cognitive,not just physical but the point is the same: stressing patients to reveal differences between patients and controls that may not be apparent on simple tasks. Multi-tasking might be another way of doing this.

Also, judging by other comments on this thread some people are hit much harder by physical fatigue than mental fatigue and these people might not show so much difference on cognitive tests. Also, if mecfs is multiple diseases, a sample of 50 is likely to be a mixed bag of different patients....

will try to get the full text later
 

Bob

Senior Member
Messages
16,455
Location
England (south coast)
The authors clearly understand that we have cognitive problems (impaired processing speed, in particular) based on their early publication.
Yes, and even in this abstract they categorically state:
"Problems with memory and attention in everyday life are a significant part of CFS."

If I'm reading the title of this paper correctly and assuming that they titled their paper appropriately (Cognitive Functioning in People With Chronic Fatigue Syndrome: A Comparison Between Subjective and Objective Measures), this study was not about us, but about the efficacy of subjective vs objective tests.
I think it's difficult to be sure about the full nature of this study without reading the full paper.

On the one hand they say that subjective and objective measures don't correlate in either patients or controls, which is very helpful information: "Scores on the subjective and objective measures were not correlated in either group."

But then they say that CFS patients' cognitive test results are no different to controls, despite reporting more cognitive problems (which seems to contradict their earlier study):
"The CFS group reported experiencing more cognitive problems than the controls, but the two groups did not differ on the cognitive tests."
 
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Hip

Senior Member
Messages
17,824
Just posting the Cognitive Failures Questionnaire for reference purposes:

Reference:
Broadbent, D.E., Cooper, P.F., FitzGerald, P., & Parkes, K.R. (1982). The Cognitive Failures Questionnaire (CFQ) and its correlates. British Journal of Clinical Psychology, 21, 1-16.

The Cognitive Failures Questionnaire (Broadbent, Cooper, FitzGerald & Parkes, 1982)

The following questions are about minor mistakes which everyone makes from time to time, but some of which happen more often than others. We want to know how often these things have happened to your in the past 6 months.

Answer options:
4 Very often
3 Quite often
2 Occasionally
1 Very rarely
0 Never

Questions:
1. Do you read something and find you haven’t been thinking about it and must read it again?
2. Do you find you forget why you went from one part of the house to the other?
3. Do you fail to notice signposts on the road?
4. Do you find you confuse right and left when giving directions?
5 Do you bump into people?
6. Do you find you forget whether you’ve turned off a light or a fire or locked the door?
7. Do you fail to listen to people’s names when you are meeting them?
8. Do you say something and realize afterwards that it might be taken as insulting?
9. Do you fail to hear people speaking to you when you are doing something else?
10. Do you lose your temper and regret it?
11. Do you leave important letters unanswered for days?
12. Do you find you forget which way to turn on a road you know well but rarely use?
13. Do you fail to see what you want in a supermarket (although it’s there)?
14. Do you find yourself suddenly wondering whether you’ve used a word correctly?
15. Do you have trouble making up your mind?
16. Do you find you forget appointments?
17. Do you forget where you put something like a newspaper or a book?
18. Do you find you accidentally throw away the thing you want and keep what you meant to throw away – as in the example of throwing away the matchbox and putting the used match in your pocket?
19. Do you daydream when you ought to be listening to something?
20. Do you find you forget people’s names?
21. Do you start doing one thing at home and get distracted into doing something else (unintentionally)?
22. Do you find you can’t quite remember something although it’s “on the tip of your tongue”?
23. Do you find you forget what you came to the shops to buy?
24. Do you drop things?
25. Do you find you can’t think of anything to say?
 
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Hip

Senior Member
Messages
17,824
In my own personal experience of my ME/CFS, I find it quite hard to provide an accurate subjective grading of my own cognitive dysfunction and overall ME/CFS symptoms, in any absolute sense.

I am always able to say whether I am better or worse than yesterday (which is a relative measure of cognitive dysfunction). But on any given day, I could not easily place myself on an absolute scale (from 1 to 10 say) of how I was feeling.

This is party because my long term memory is appalling, so I very quickly forget how I was feeling last week and last month, which makes it hard to gauge in absolute terms how I am feeling on any particular day. But I can remember how I was feeling yesterday, and so it is easy for me to say whether I am feeling better or worse than yesterday.

I see this as a bit of a problem, because it makes it hard for me (and no doubt other ME/CFS patients) to judge whether a given medication regimen is having beneficial effects or not.

However, what I tend to do is use natural objective measures of my heath level. For example, by noting the number of bedbound days I have per week, this gives me a natural objective gauge of my health level. Or I might note how many times I tend to leave the house per week (the healthier I am, the more I tend to go out). Or I might note just how much complex reading or writing I was doing in a given week (the less brain fog I have, the more I am able to tackle complex subjects).

I seem to be able to remember these more objective details. If these more objective measures of my heath level indicate an improvement, then I feel more confident that my current regimen is doing me good.
 
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SOC

Senior Member
Messages
7,849
In my own personal experience of my ME/CFS, I find it quite hard to provide an accurate subjective grading of my own cognitive dysfunction and overall ME/CFS symptoms, in any absolute sense.

I am always able to say whether I am better or worse than yesterday (which is a relative measure of cognitive dysfunction). But on any given day, I could not easily place myself on an absolute scale (from 1 to 10 say) of how I was feeling.

This is party because my long term memory is appalling, so I very quickly forget how I was feeling last week and last month, which makes it hard to gauge in absolute terms how I am feeling on any particular day. But I can remember how I was feeling yesterday, and so it is easy for me to say whether I am feeling better or worse than yesterday.

I see this as a bit of a problem, because it makes it hard for me (and no doubt other ME/CFS patients) to judge whether a given medication regimen is having beneficial effects or not.

However, what I tend to do is use natural objective measures of my heath level. For example, by noting how many days per week I need to stay in bed for 18 hours a day or more. Or I might note how many times I tend to leave the house per week (the healthier I am , the more I tend to go out). Or I might note just how much complex reading or writing I was doing. I seem to be able to remember these more objective details. If these more objective measures of my heath level indicate an improvement, then I feel more confident that my current regimen is doing me good.
This is exactly my experience, too.
 

alex3619

Senior Member
Messages
13,810
Location
Logan, Queensland, Australia
Just posting the Cognitive Failures Questionnaire for reference purposes:

Reference:
Broadbent, D.E., Cooper, P.F., FitzGerald, P., & Parkes, K.R. (1982). The Cognitive Failures Questionnaire (CFQ) and its correlates. British Journal of Clinical Psychology, 21, 1-16.

What does it mean if you have very often or quite often for almost all if the questions? :D
 

jeffrez

Senior Member
Messages
1,112
Location
NY
Cognitive Functioning in People With Chronic Fatigue Syndrome: A Comparison Between Subjective and Objective Measures.
Cockshell SJ, Mathias JL.
Neuropsychology. 2013 Dec 23. [Epub ahead of print]
http://www.ncbi.nlm.nih.gov/pubmed/24364389/?ncbi_mmode=std

Abstract
Objective: The purpose of this study was to examine the relationship between subjective and objective assessments of memory and attention in people with chronic fatigue syndrome (CFS), using tests that have previously detected deficits in CFS samples and measures of potential confounds. Method: Fifty people with CFS and 50 healthy controls were compared on subjective (memory and attention symptom severity, Cognitive Failures Questionnaire, Everyday Attention Questionnaires) and objective (California Verbal Learning Test, Rey-Osterreith Complex Figure Test, Paced Auditory Serial Addition Test, Stroop task) measures of memory and attention. Fatigue, sleep, depression, and anxiety were also assessed. Results: The CFS group reported experiencing more cognitive problems than the controls, but the two groups did not differ on the cognitive tests. Scores on the subjective and objective measures were not correlated in either group. Depression was positively correlated with increased severity of cognitive problems in both the CFS and control groups. Conclusions: There is little evidence for a relationship between subjective and objective measures of cognitive functioning for both people with CFS and healthy controls, which suggests that they may be capturing different constructs. Problems with memory and attention in everyday life are a significant part of CFS. Depression appears to be related to subjective problems but does not fully explain them. (PsycINFO Database Record (c) 2013 APA, all rights reserved).

:rolleyes:

They must have had some pretty dumb controls.

Iow, what this abstract is saying is that whatever cognitive problems people with CFS report are "all in their heads," and that any cognitive problems that do actually exist are because of depression.

:rolleyes: