Cognitive testing causes mental exhaustion lasting days

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Simon McGrath takes a brief look at a recent paper that reveals some of the most powerful evidence of cognitive problems in people with ME/CFS to date...

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It might not come as a huge surprise to patients, but a new study has found that mental fatigue can persist long after mental exertion is over.

Specifically, after a 3-hour session of cognitive testing of memory and attention, healthy controls took an average of 7 hours to recover, compared with 57 hours - more than two days - for CFS patients.

While one previous study found mental fatigue continues days after physical exertion, this appears to be the first research paper to demonstrate that mental exertion itself leads to prolonged mental fatigue.

To me, the large difference found between patients and controls makes this some of the most powerful evidence of the cognitive problems in ME/CFS.

Interestingly, this finding only came about thanks to the alertness of Susan Cockshell, the lead researcher who told me:

“I hadn’t originally planned to collect this data, but I had to follow up one of my first participants a few days after testing and she told me she was still fatigued.” ​

So, post-test mental fatigue was added to the measures.

Mental fatigue for both healthy controls and patients peaked several hours after testing (albeit at lower levels for controls), but 24 hours later, controls were back to pre-test levels while patients were not.

It’s hard to believe we've waited till now to even see testing of post-exertional mental fatigue. Cockshell commented that surprisingly little data existed in this area, but her study shows it is an issue that needs further investigation.

Subjective measures don't match objective measures

The main aim of the study was actually to see if patients’ reports of problems with mental tasks were backed up by objective test of cognitive function - specifically of memory and concentration, two distinctive problems with ME/CFS.

The result? There was no significant correlation between patient reports of fatigue and measured cognitive performance. But this doesn’t mean that patients don’t really have problems with mental tasks because, as Cockshell pointed out, there was also no correlation in healthy controls either (healthy controls reported some problems with memory and concentration too).

The paper concludes:

“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.”​

In fact, a lot of evidence now shows that people’s self-reported cognitive problems aren't matched by the kind of objective tests used in these studies, which does beg the question: Do we need better tests of cognitive problems in the real world?

To understand this issue better, let’s take the example of concentration, which in the real world means problems such as focusing on reading or blocking out background noise. One measure of concentration (or ‘attention’ in the jargon) is the "Stroop" - a quirky test with a quirky name.

The simplest way to see how it works is just to look at the two lists above. Don’t read them, instead say the colour each word is displayed in, as quickly as you can. Not so easy, but try it online!

Of course, we never have to do tasks like this in real life (and most other cognitive tests are similarly contrived), so is this a meaningful way to measure patients’ problems?

One researcher and clinician, Gudron Lange, has highlighted how everyday tasks, such as going shopping, involve multi-tasking, something that most cognitive tests miss.

Lange has suggested using cognitive tests that include multi-tasking – and virtual reality now provides a way to test real-life scenarios using multi-tasking in the lab.

Cockshell agrees that more work is needed in this area:

“I think a better understanding of the cognitive problems occurring in the real world is required ... but that's a whole other area of research.”​

Patients don’t overestimate their problems

Some researchers have argued that the problem in CFS isn't that patients can't do much or perform well, but that they simply underestimate how much they actually do, almost seeing CFS as a delusion syndrome. But this new study, like several others, found that the theory doesn’t hold up:

“Self-reported problems were not due to people with CFS overestimating their problems, as they were able to accurately evaluate their performance on most cognitive tests.”​

In fact, patients were at least as good as controls at judging their own performance.

The future...

These clear findings of extended fatigue after the testing fit with an earlier fMRI study (also by Lange), indicating that CFS patients had to use more brain areas to achieve the same results as healthy controls. As Cockshell says:

“People with CFS may perform comparably to their peers by expending additional cognitive effort, and this may subsequently impact on their levels of fatigue.”​

This paper provides powerful new evidence of the problems faced by patients with our condition. Yet the mismatch between reported issues and objective performance suggests there we still haven’t found the best way to measure the very real problems experienced by ME/CFS.

Hopefully, this will soon change.

Susan Cockshell will be speaking about her work at the IACFS Conference on Sunday 23.3.14. Read more: Brain Fog: The research.

Simon McGrath tweets on ME/CFS research:

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I hope it's possible to disprove any claims by psychologists/psychiatrists that our cognitive difficulties aren't psychological in origin!

It's not possible. Claims of psychosomatic illness are not tied to any objective criteria, so they cannot be proven or disproven. They are purely a matter of faith.

 

Thanks Simon.

I'm with you. There's been too much emphasis on 'malaise' following physical exertion which feeds into the whole deconditioning and GET as rehabilitation meme.

Although I've never been deconditioned as such, physical capacity was pretty irrelevant to my deskbound job and wouldn't have hampered me any more than any other sedentary office worker.

It was a severe lack of cognitive stamina that was a major contributor to my inability to work and which still interferes with everyday tasks.

I also agree that real world challenges that involve multi-tasking are more likely to highlight cognitive deficits and their lasting effects that are more than mild or trivial.

I wrote about this large study that found profound cognitive deficits using a multi-tasking paradigm :

http://www.cortjohnson.org/blog/201...deficits-present-in-chronic-fatigue-syndrome/

This is a very under-researched area and one that I feel may be much more relevant to what's going on than physical fatigue.

Thanks, Marco, and an interesting blog of yours too.

I think both mental and physical fatigue are valid to measure but I wish mental fatigue wasn't so neglected. I've had relapses from both physical and mental overexertion and, as you say, mental fatigue is hard to explain by deconditioning. I once met someone who was permanently bedbound due to his condition, yet could watch a whole film - something I could only dream of at the time as a 5-min conversation exhausted me.

I've been very impressed by Susan Cockshell and hope that she, and people like her, will start to throw more light on the cognitive problems in this illness. I think that so far researchers have only scratched the surface.

 

This is my most disabling symptom as well..it was interesting to read what I have known all along. I was able to do.my job fine but after a 6 hour shift I could barely make it home as the mental exhaustion was horrible . I also have huge problems just riding in a car for long periods of time as just looking around and taking in the traffic and scenery will exhaust me for days. That is why I can't drive far..I am okay getting there but after doing errands etc..I am fried. I really have no problems physically but the mental fatigue is very disabling and feels so bad....

 

Claims of psychosomatic illness are not tied to any objective criteria, so they cannot be proven or disproven. They are purely a matter of faith.

What if a large, double-blinded study showed that patients responded well to a physiology-based treatment, so that they no longer had any symptoms that might be attributed to psychological causes? Hasn't this happened in the past with illnesses once thought to be psychological?

 

Claims of psychosomatic illness are not tied to any objective criteria, so they cannot be proven or disproven. They are purely a matter of faith.

What if a large, double-blinded study showed that patients responded well to a physiology-based treatment, so that they no longer had any symptoms that might be attributed to psychological causes? Hasn't this happened in the past with illnesses once thought to be psychological?

Showing that peptic ulcers were caused by the bacterium H. pylori and can be treated with antibiotics is the classic case.

I've always thought that the only way the psychosomatic argument will finally be laid to rest is by positively proving what does cause ME/CFS, whether that involves physiology-based treatment or not (though clearly treatment would help). It's possible that some cases of CFS do have an important causal psychological component and maybe that's a relevant subgroup, but only a subgroup.

 

What if a large, double-blinded study showed that patients responded well to a physiology-based treatment, so that they no longer had any symptoms that might be attributed to psychological causes? Hasn't this happened in the past with illnesses once thought to be psychological?

In practice psychosomatic explanations are abandoned once concrete physiological explanations are found. However, whereas previously the idea was that there are no physiological abnormalities, when faced with evidence for the contrary, the psychosomatic camp seems to be shifting their stance towards claiming that the mind is creating the physiological abnormalities fully in some cases, and at least in part in others. Essentially the psychosomatic camp is trying to position themselves as relevant in illness, and it's still not possible to prove or disprove their claims.

 

Showing that peptic ulcers were caused by the bacterium H. pylori and can be treated with antibiotics is the classic case.

I've always thought that the only way the psychosomatic argument will finally be laid to rest is by positively proving what does cause ME/CFS, whether that involves physiology-based treatment or not (though clearly treatment would help). It's possible that some cases of CFS do have an important causal psychological component and maybe that's a relevant subgroup, but only a subgroup.

Yes, I agree that some of us probably have a psychological component in the initial causation (ditto for a range of other physical illnesses), but not in the perpetuation of the illness, so psychological treatments are pointless once any psychological (as opposed to neurological and cognitive) problems have gone, leaving just the physical consequences. I often use the analogy of the folly of trying to treat a bullet wound by putting the bullet back in the gun.

 

And what if the bullet cannot be taken from the wound, or the wound will not heal: how do you help people to learn to live with the horrors of a gunshot wound? Or the medicine proves too expensive for everyone to receive? If a cause is established and a treatment that heals can be made available to one-and-all: great. Chances are it wont happen like that. 'Psychology' ain't all bad and much counseling may still be required. But it would remove theories pertaining to a 'psychological' cause - provided of course your particular ME was the one that had the biomarker.

 

Easily, overwhelmed?

I would bet that most people who go on to develop ME/CFS were born "highly sensitive".. This is a normal trait found in 15 to 20 percent of the population. The brains of highly sensitive persons (HSPs) actually work a little differently than others. Highly sensitive people are born more susceptible to physical, emotional and mental exhaustion.

Are You Highly Sensitive?

A Self-Test http://www.hsperson.com/pages/test.htm

 

I would bet that most people who go on to develop ME/CFS were born "highly sensitive".. This is a normal trait found in 15 to 20 percent of the population. The brains of highly sensitive persons (HSPs) actually work a little differently than others. Highly sensitive people are born more susceptible to physical, emotional and mental exhaustion.

What a bunch of pointless garbage.

 

What a bunch of pointless garbage.

Surely you meant to say "What a bunch of psychobabble"?

 

If you can't walk you can use a wheelchair, if you can't think straight - there are no props

Well, there are some cognitive enhancers available.

 

Easily, overwhelmed?

I would bet that most people who go on to develop ME/CFS were born "highly sensitive".. This is a normal trait found in 15 to 20 percent of the population. The brains of highly sensitive persons (HSPs) actually work a little differently than others. Highly sensitive people are born more susceptible to physical, emotional and mental exhaustion.

Are You Highly Sensitive?

A Self-Test http://www.hsperson.com/pages/test.htm

Having looked at the set of questions it seems to me they are lumping together different concepts. I haven't looked at any papers so I have no idea as to whether such clustering is justified. Then there is the reading of generalizable consequences into their very broad classification.

Put simply they seem to lump together physical sensitivity (i.e. people with good senses) with emotional sensitivity (people who have good empathy with others) along with other concepts as well. Can this be justified in terms of then giving a broad label to a person when the actual characteristics of two people with the same label need not overlap much.

It seems to me that researchers get away with this type of approach due to the lack of an underlying mathematical formalism which allows them to never state a hypothesis which if they did wouldn't be meaningful.

 

This study found a CFS cohort no more sensitive than controls:

An investigation of sympathetic hypersensitivity in chronic fatigue syndrome.

OTOH, the authors of this paper suggest "sustained arousal" in CFS:

Abstract
We present an integrative model of disease mechanisms in the Chronic Fatigue Syndrome (CFS), unifying empirical findings from different research traditions. Based upon the Cognitive activation theory of stress (CATS), we argue that new data on cardiovascular and thermoregulatory regulation indicate a state of permanent arousal responses – sustained arousal – in this condition. We suggest that sustained arousal can originate from different precipitating factors (infections, psychosocial challenges) interacting with predisposing factors (genetic traits, personality) and learned expectancies (classical and operant conditioning). Furthermore, sustained arousal may explain documented alterations by establishing vicious circles within immunology (Th2 (humoral) vs Th1 (cellular) predominance), endocrinology (attenuated HPA axis), skeletal muscle function (attenuated cortical activation, increased oxidative stress) and cognition (impaired memory and information processing). Finally, we propose a causal link between sustained arousal and the experience of fatigue. The model of sustained arousal embraces all main findings concerning CFS disease mechanisms within one theoretical framework.

I guess sustained arousal would cause someone to be hypersensitive, and perhaps vice versa.

 

This study found a CFS cohort no more sensitive than controls:

An investigation of sympathetic hypersensitivity in chronic fatigue syndrome.

OTOH, the authors of this paper suggest "sustained arousal" in CFS:

I guess sustained arousal would cause someone to be hypersensitive, and perhaps vice versa.

I find it perfectly scientifically plausible that people can be born with unusually-high psychological sensitivity, and can also acquire such sensitivity due to prolonged psychological stress in childhood, via effects on the stress hormone system, as we have discussed elsewhere.

This paper provides some evidence on the effects of maternal stress on a foetus.

I am not looking to blame mothers, by the way!

 

I find it perfectly scientifically plausible that people can be born with unusually-high psychological sensitivity, and can also acquire such sensitivity due to prolonged psychological stress in childhood, via effects on the stress hormone system, as we have discussed elsewhere.

This paper provides some evidence on the effects of maternal stress on a foetus.

I am not looking to blame mothers, by the way!

This is known as the kindling model:

Neurosci Med. 2011 Mar 1;2(1):14-27.
An Etiological Model for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
Jason LA1, Sorenson M, Porter N, Belkairous N.
Author information

Abstract
Kindling might represent a heuristic model for understanding the etiology of Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS). Kindling occurs when an organism is exposed repeatedly to an initially sub-threshold stimulus resulting in hypersensitivity and spontaneous seizure-like activity. Among patients with ME/CFS, chronically repeated low-intensity stimulation due to an infectious illness might cause kindling of the limbic-hypothalamic-pituitary axis. Kindling might also occur by high-intensity stimulation (e.g., brain trauma) of the limbic-hypothalamic-pituitary axis. Once this system is charged or kindled, it can sustain a high level of arousal with little or no external stimulus and eventually this could lead to hypocortisolism. Seizure activity may spread to adjacent structures of the limbic-hypothalamic-pituitary axis in the brain, which might be responsible for the varied symptoms that occur among patients with ME/CFS. In addition, kindling may also be responsible for high levels of oxidative stress, which has been found in patients with ME/CFS.

 

And what if the bullet cannot be taken from the wound, or the wound will not heal: how do you help people to learn to live with the horrors of a gunshot wound? Or the medicine proves too expensive for everyone to receive? If a cause is established and a treatment that heals can be made available to one-and-all: great. Chances are it wont happen like that. 'Psychology' ain't all bad and much counseling may still be required. But it would remove theories pertaining to a 'psychological' cause - provided of course your particular ME was the one that had the biomarker.

Now you have taken my simple analogy and gone on a convoluted journey with it, and I am lost!

Of course if someone is suffering from the effects of emotional trauma it is sensible to treat it. Please note the pertinent phrase in my message to which you appear to be replying:

...psychological treatments are pointless once any psychological (as opposed to neurological and cognitive) problems have gone, leaving just the physical consequences.

 

I do think multi-tasking is a critical area to test. I can sustain more normal levels of certain types of thinking for far longer, but trying to hold multiple concepts in my working memory at once is far and away one of the most difficult things for me to do (like remembering a phone number while also doing some kind of other simple processing, for example, is brutal. Remembering two sets of rules and comparing them would be really hard too. Anything where I have to retain information about two things at once). I can write a little if I do it train of thought, but editing, modifying, moving phrases around is exhausting and brings on my particular kind of head/spine pain.

I've tried to pay close attention to what is harder for me, and I'm quite certain it has something to do with my working memory. It would be interesting to know if that was true for many patients, though, or if it's unique to me or a subset.

I've always found it so weird that certain kinds of mental effort are so much easier than others. I can still answer trivia questions on a really bad day. But I can't follow simple instructions, or do basic math that involves more than one step at once.

 

Easily, overwhelmed?

I would bet that most people who go on to develop ME/CFS were born "highly sensitive".. This is a normal trait found in 15 to 20 percent of the population. The brains of highly sensitive persons (HSPs) actually work a little differently than others. Highly sensitive people are born more susceptible to physical, emotional and mental exhaustion.

Are You Highly Sensitive?

A Self-Test http://www.hsperson.com/pages/test.htm

No, I'm not easily overwhelmed. Neither is my daughter or my uncle, both PWME as well. We aren't "highly sensitive", either. I'm willing to bet we are not alone among PWME.

This "highly sensitive person" stuff reads like a bunch of psychobabble conflating empathy with acute senses for no other reason than that the word "sensitive" is often used in the context of both situations.

 

I often find myself in a situation where Michael will ask me where something is.
Despite my being is a bad physical way at the time, I still find it easier to get up and get whatever he is asking for,
rather than to try describe where it is.

Then he moans about me wasting energy.

Simple recall of facts does not require too much input from working memory, (the trivia Sparrow mentions) but working something out (arithmetic) where you have to do things with facts in the working memory does take a lot of effort.