The maintained attention assessment in patients affected by [ME/CFS]: a reliable biomarker?, Murga et al, 2021

[Hoopoe]

A problem I have that doesn't seem to be discussed is the inability to maintain interest in projects and bring things to completion. Part of that is the effect on the brain of exertion intolerance which builds up over time as one tries to get things done on a regular basis but I think there might be different kind of inability too which could be described as difficulty maintaining attention over longer periods of time. Normally difficulty with concentration and attention refers to phenomena in the time span of minutes to hours. I see some serious problems occurring in the time span of days to weeks. I start with good motivation intending to do something, but the motivation decreases over time until the idea that initially aroused enthusiasm is of no interest. Sometimes this loss of interest can occur from one day to the next.

 

[Sean]

Though people who wind up in research studies tend to be hyper-educated (lest we ever think they are really random samples).

Study participants also tend to be available. Same problem that jury selection has.

 

[Ash]

One potential way is to seek to match the patient and normal groups on a factor that is presumed to relate to premorbid cognitive ability, such as level of education or previous work status. So you would seek to find a match pair for each patient to make up the control group, and you would measure the difference between the patient and their matched control rather than between the group averages. However, it is not clear how doable this is without some independent confirmation that we could reasonably expect that say solicitors would have similar premorbid baselines as other solicitors and say postmen would have similar premorbid baselines as other postmen.

The only sure fired way to get round the lack of a premorbid baseline, is to to have samples that can be unambiguously said to represent what is normal for the target populations. Usually this can only be achieved where the sample size is large enough to eliminate any possibility that between group differences are not due to normal individual differences within the sample, or if the between group differences are so big as to make normal variation an implausible explanation, usually an all or nothing difference.

Personally, my cognitive difficulties, other than my specific issues with such as spelling or navigation, depend on processing load, any distractions and novelty of the task.

I can read most single sentences, but my reading comprehension brakes down on longer passages requiring integration of information between sentences containing unfamiliar vocabulary items or under time pressure, so premorbidly I would read three or four books a week including non fiction, whereas now I have only managed to read two books in the last five years, each taking over six months with frequent re reading of chapters, whereas I probably process the same volume of text as premorbidly but in the form of Facebook posts or forum comments.

My ability to place an on line order depends on my familiarity with the site and/or the items being purchased, so I can, having had supported practice of making on line grocery orders, now reasonably order my groceries unaided from my saved list of favourites, but then fail at the superficially simpler task of a one-off turf order on a site that only required me to fill in a total area and a delivery date, where failing to accurately add three numbers together I ordered 1,500 square metres, rather than the required 500 hundred square metres (in retrospect I now know I should have got the person doing the measuring to also total the three component areas, and have learnt to only use unfamiliar sites when there is someone present to check my order before a final purchase.)

I have overstretched myself reading or attempting to forum posts in recent months.

Started with NICE stuff and relatedly looking at BPS up close again. This area of politics has direct consequences for my day to day life. So unpleasant as it is I find it necessary to re engage at intervals.

However I was only able to overstretch due to the relative brevity of posts.

Able to skim over less familiar material. As posts are pretty self contained references back usually to one other source and general background situation, the latter being fairly familiar to me in most cases.

I enjoy reading long-form articles most and used to read books often. I can’t do this now because of how far back the references go. I find it very difficult to follow forgetting ground covered. So I don’t overextend in these areas because multiple failed attempts have left me too discouraged to begin.

I feel very sad about this. Every day I want to engage in deep learning and this desire never goes away.

The difficulties you describe here @Peter Trewhitt fit with my experience perfectly. Thank you for sharing, it is comforting to see it explained outside my own experience.

I cannot manage numbers, very simple numbers. Even counting days of week until apps I get lost and confused. This makes life very difficult and is absolutely exhausting.


Online shopping is extremely difficult. Not from lack of practice. I forget how to do things I done repeatedly for years. Even my weekly shop.

However I can do a familiar shop with all details pre saved and be worn out for a few hours or 24.

Whereas an unfamiliar ordering process is impossible for me to navigate most of the time. When I do I manage usually takes at least 4 days to recover energy and brain function afterwards.

 

[Sean]

Online shopping is extremely difficult. Not from lack of practice. I forget how to do things I done repeatedly for years.

Been using eBay for years, but literally minutes ago I selected the obviously wrong size of an item on a drop-down menu, and didn't notice until after paying. FFS, I was looking straight at the menu when I selected it, but still missed it, my mind just saw something else. So have had to ask the seller to cancel the order.

Then there was the time I couldn't figure out why substantial sums were sporadically disappearing from my bank account. Turns out it was payments to my dentist, who did not use any dental related words in his business name, just some generic name.

I realised my mistake at the bank, as I was discussing it with the manager.

She was very nice about it. But, boy, did I feel like an idiot. It's not like I have a lot of money to keep track of.

 

[Simon M]

Answers from lead author Dr Inigo Murga to questions posed on this thread

My thanks to Dr Murga for replying to questions I passed on. I don't have permission to share his email and so will summarise his points.

Highlights
The apparently-odd fatigue scores were accounted for by just a few individuals and so wouldn't affect the results materially. Education levels for patients were very high (61% had at least a university degree) so this could not account for the low patient scores. The authors are looking for funding to do a replication that would also include EEG readings (electrical impulses from the brain measured on the scalp) and measures of IDO metabolism.

They don't seem to have access to any patients who were not on high levels of medication so cannot address this issue. I hope that other researchers will attempt to replicate these findings on patients either without medication or with a medication-matched control group.

Murga also pointed out that this 10-minute test causes marked and fast fatigability, which is perceived as very tiring (Borg exertion scale: patients 7.7 vs HC 1.8/10). And 76% ' have an obvious congnitive deficit (i.e. score of "low" or worse).

The detail will follow in a later post.

 

[Simon M]

Lead-author replies to questions raised here about the study - cont...

More detail

1. Could you comment on the apparently-odd fatigue scores?
The lowest patient fatigue scores were very low (0 pre-test, 10 post-test) and the highest control score was very high (70 pre and post-test).
These were accounted for by a few individuals. A single patient accounted for both low fatigue scores [which might cast doubt on the diagnosis]; 19/22 controls scored 0 fatigue both before and after the test. The three others scored 10, 40 and 70 with no change in the score after the test.

This information is consistent with the average fatigue scores reported in the paper:
pre/post
Patients: 62/78
Controls: 5.5/6.4

2. Could the lower scores for patients be due to lower education levels?
Murga didn't give me any data on the controls but patients were clearly highly educated:
University studies (41.66%) + master's degree (14.28%) + doctorate 4.76%) = 60.7%.

3. Are you planning any studies to examine the impact of medication on scores?
He said it would not have been ethical to withdraw medication and "it is a variable that must always be kept in mind". But they have looked at depression which did not make a difference to scores.

My comment: the difference between patients and controls is huge. I haven't seen any evidence that medication could account for such a big effect.

 

[Michelle]

There are known deficits for pwME on formal neuropsychological testing. Sustained attention is concentration, then manipulating the information requires intact working memory and processing speed is reduced in ME/CFS

I actually won my disability appeal in 2003 based on my neurocognitive testing, which was the only "objective" evidence of impairment I had at the time. When I applied for disability in Sept 2001, I was immediately referred by Social Security to a psychologist for said testing as is standard for all claims. It took 5 hours. At the end of all of that, it showed that I was having "moderate difficulties with concentration and short-term memory," and that I was "processing information significantly slower" than my IQ suggested I should have been.

And I could still do stuff, like, say, drive at that point. I don't even want to think what they would find now. Not that they would be able to spend 5 hours testing me. After an hour (on a good day!) I would absolutely have to rest. And it would have to be done from my bed as I can't get to a clinic.

 

[Kitty]

the difference between patients and controls is huge: I haven't seen any evidence that medication could account for such a big effect.

Especially as people habituate to many medications fairly quickly. They may still have some effect, but of course not all of them will reduce a person's cognitive capacity—some may improve it by reducing symptoms that would otherwise be distracting.

 

[Samuel]

i couldn't sustain attention on the instructions or figure out what to do with the test from its behavior. idk if this was useful for me to say.