Brain fog: The Research

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Simon McGrath on some important recent research into cognitive deficits in ME/CFS.

Brain fog is a major issue for ME/CFS patients, with 80-95% reporting memory or concentration problems. And while researchers have often found evidence of 'cognitive deficits' in laboratory testing, a surprising number of studies have failed to find deficits, leaving some to even speculate that patients' cognitive problems are more perceived than real.

Clearing away the smoke


Such inconsistent findings are almost the norm for CFS research, with similarly mixed results in many areas including biomarkers. How do you make sense of it all?


Susan Cockshell: She does all this part-time?

Step forward Susan Cockshell, a new researcher only able to work on her PhD part-time, to clear away some of the smoke. A few years ago she published a large meta-analysis on cognitive problems in CFS. A search through a thousand possible studies was eventually narrowed down to fifty 'good' ones that between them had over 1,500 CFS patients and 1,500 controls. This was a major piece of work.

A meta-analysis looks at all the studies' results as a whole, in a statistically robust way, to see if an overall effect emerges - and in this case it did. Cockshell, working with Professor Jane Mathias, found that there were substantial effects in attention, memory and Reaction Time. These fit with the memory and concentration problems reported by patients:



ME/CFS: slower reactions

What reaction time tests


Reaction time isn't just a measure of how fast you can move your muscles, but how quickly you can register information and THEN move. Think gunslingers at High Noon, who had to wait for the clock to strike before drawing (unless they cheated, of course). Susan Cockshell’s work suggests the slowdown in ME/CFS is with registering the information, not the muscle movement in response.


"This study provides objective evidence of cognitive deficits in persons with CFS, primarily in the domains of attention, memory and reaction time. In general, these deficits are consistent with those that are reported by patients... The deficits in performance are [substantial], which is likely to have an impact on day-to-day activities"

They also found issues with ‘motor functioning’, which is a measure of how quickly a muscle can respond to a command from the nervous system to move. However, verbal abilities, global functioning and cognitive flexibility and reasoning were normal, or only slightly affected, across many different studies.

Large study adds support


A large study in 2010 backed this up by demonstrating that CFS patients have substantial problems with attention, reaction time and memory. This carefully controlled experiment, with over 300 CFS patients (Fukuda definition), also looked at the effect of mood and anxiety, which are more common in CFS patients and might explain the cognitive problems. However, it found that differences in the levels of anxiety and depression could not account for the difference in cognitive performance between patients and healthy controls.


Do the Stroop & other cognitive tests


The Stroop is a quirky test of attention, with a quirky name. The simplest way to see how it works is just to look at the two lists on the right. Don’t read them, instead say the color each word is displayed in, as quickly as you can. Not so easy... Try it online!

Test your reactions



React to the green target in the Simple test. In the 'Choice' version, you are sometimes presented with a target you need to ignore, so you have to choose before reacting: Try it!

Memory: PASAT (Paced Audio Serial Addition)


Tests memory, but sometimes considered an attention task too: easier to try than to explain. Try it! More tests at the excellent Cognitive fun website

Instead, they found that the current level of fatigue and total number of symptoms explained differences between patients and controls, just as expected. They also found that patients who reported more problems with minor cognitive tasks in the previous 6 months performed less well on tests than those reporting fewer problems. In other words, patients' self-rating of cognitive difficulties matches performance in cognitive tests - indicating that the problem is not one of perception.

All of this backs up what patients have been saying for years. Except... these results are still not that clear cut. For instance, looking at fatigue in just the last 2 weeks, general fatigue scores correlated with cognitive performance, but mental fatigue did not, which is surprising. And while patients' self-rating of cognitive problems matched performance on reaction times, they did not match performance on other tests, such as memory and attention.

Just when it looks sorted...


A new and very thorough paper from Susan Cockshell throws some more light on the situation, but some of its findings add to the confusion too.

The study does some really neat things. First it checked for subject effort, to tackle the criticism that patients' poor performance might be because they weren't really trying. Well over 90% of patients were shown to be giving full effort - the same proportion as healthy controls, and strong evidence against the 'not trying hard enough' view. The few patients and controls that might not have been applying full effort were excluded from the study, leaving 50 in each group.

Like the 2010 study above, this new research controlled for psychological factors such as anxiety, and again showed that these factors made little difference to results. The new paper also confirmed the large difference in reaction time, with patients much slower than controls.

However, in some important ways the new study results conflict with earlier findings, e.g. no differences were found in either memory or concentration (though statistically, some studies will inevitably miss real effects by chance alone). For me, though, the most dramatic finding was that there was no correlation between patient-reported physical function or fatigue and cognitive performance, a very surprising result. New research from Susan Cockshell looks at this area in more detail, measuring fatigue after testing as well as before: the paper has been submitted but science publishing can move slowly so results may not appear for another 6 months.

What next?


Almost every study finds that CFS patients have slower reaction times. Most show that patients have problems with attention and memory too, and these differences cannot be explained by differences in psychological factors such as depression. And almost all studies show that there are no obvious problems with higher-level functions such as reasoning.

However, quite often no substantial effects are found for memory, attention or motor functioning, and the correlation between patient-reported problems and test performance is surprisingly weak. Several things could explain this:

  • Perhaps many of the cognitive problems are not as bad as patients believe, making the differences hard to detect, and accounting for the weak correlation with patient-reported problems. More plausibly:
  • The highly specific and artificial lab tests of cognition may not relate well to real-life mental tasks such as office work.
  • The tests may not be demanding enough to reveal differences, at least not consistently. A new fMRI brain study shows that CFS patients use more brain regions than controls just to do simple memory tasks: ie more 'brain power' is needed to produce the same effect.
  • If the issue is fatigability, rather than ongoing fatigue, then repeat or extended testing might reveal differences that a small number of single tests do not. And the new work by Susan Cockshell looking at fatigue after tests may also show up differences with controls.
  • Studies vary widely in the specific types of tests, and given the heterogeneity of CFS, they probably vary in types of patients too. This could lead to very mixed results.

Clearly more work is needed to pin down the nature of cognitive problems in CFS, and the mismatch between reported problems and lab-based test results. Susan Cockshell notes that such differences are common in other illnesses too, such as stroke. In fact, her initial interest was in cognitive problems generally in illness, and she chose CFS specifically for her doctoral work as she thought this was an area where she could make a difference. She will be submitting her thesis soon and we can expect much more from this researcher in future.

Simon McGrath has a science degree, and has watched not much happening in ME/CFS research for a long time, but now thinks things are finally kicking off. He occasionally tweets on research: follow @pSimonMcGrath



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Comments

Thanks Simon. Very informative.
Memory is a big one for me. I can't remember things after even a short amount of time, and the registering of information is definately a problem for me too. I can look at the time on a clock, but not understand what the time is. I have to really focus to process it. Same for reading, some days I have to read everything twice, at least, in order to take it in, or hear a question multiple times before I can answer. It's good to see that people are looking at these things.
 
Thanks Simon. Very informative.
Memory is a big one for me. I can't remember things after even a short amount of time, and the registering of information is definately a problem for me too. I can look at the time on a clock, but not understand what the time is. I have to really focus to process it. Same for reading, some days I have to read everything twice, at least, in order to take it in, or hear a question multiple times before I can answer. It's good to see that people are looking at these things.
Thanks, snowathlete

My memory is lousy too, though in my case I think that's more down to age... Registering - or rather understanding - information can be a real bugbear for me as well. I'm fine for a while then it suddenly goes and it's as if the words are jumping off the page at me, or someone is speaking but I can't connect their words together into a sentence.
 
Yes - good that this is being looked at, including seeing how people are affected by the demands of the test itself. From my own experience I would expect mental fatigue to set in quickly just as physical fatigue does, and maybe it is related to lactic acid levels as physical fatigue has been found to be in ME.

Re the comparisons with healthy people, it's a shame that we don't have baseline values for how people performed before getting ME. I wonder if there is a group of sufferers who have taken such tests before becoming ill - taken for some other reason.

My thinking is that (and I know some people are strongly opposed to suggestions of 'ME personality traits'), I and many sufferers with whom I have corresponded are perfectionists and very demanding of ourselves, perhaps more than the general public. This, and a change from baseline, could at least partly account for why our results do not always correlate with our perceptions. We don't think we are doing 'well enough' or as well as we used to, and the latter may be correct.

Our tendency to push ourselves hard, and beat ourselves up if we don't do as well as we think we should, is likely to be a factor in the development of the illness. In my view anyway.

I know there has been a study that found we did not have characteristic personality traits, but that was carried out by a certain Simon Wessely et al. (Maybe there are others.)
 
I had huge brainfog, could not even type 3 words or find a bill in a pile some years ago. The names of my children, the road to home, ... it was a disaster. Things have improved since a year. I can write and read a lot. I took a lot of supplements but I guess it is a combination of Low dose naltrexone, licorice root, biotin and D-phenylalaline that did the trick. Biotin in high dosage (10 mg) kills candida and lifts part of the brain fog. Licorice root supports the adrenals and when they start working again (let's say after 9 months of use) it does make a difference. Low dose naltrexone (LDN) is very strong and causes in most people kind of herxheimer reactions for months. You'll have to start very low (0,25 mg for a month before slowly increasing the dose). You produce more endorphines and it had a huge impact on my brain. In the beginning extreme headaches but apparently it was part of my healing. LDN also gives you more energy but it'll affect your sleep in the beginning. Consider 5-HTP of some melatonin to sleep. D-phenylalaline is what is needed to make neurotransmitters. It helps me to be in good mood and apparently to have a better memory as well after extensive usage.
Wish you all the best.
 
Nice post Simon

I'll be blogging on a similar vein on Health Rising in the near future.
 
Thanks Simon. I found planning to be a tough mental task.

I can make great decisions given a set of information in front of me. Long as I don't have to remember anything and apply it at a later time or date
 
very interesting about us utilising more brain regions to do the same job and perhaps means more of us should have a crack at taking piracetam which decreases EEG complexity , in my understanding it makes sure the corpus callosum has plenty of choline to make it easier for signals to jump from one neuron to the next and because it is targetting the callosum the left and right brain hemisphere communication is more efficient
 
Yes - good that this is being looked at, including seeing how people are affected by the demands of the test itself. From my own experience I would expect mental fatigue to set in quickly just as physical fatigue does, and maybe it is related to lactic acid levels as physical fatigue has been found to be in ME.
I Reading this thread so far, there seem to be a wide range of different cognitive problems and I suspect each person would have a different threshold before fatigue sets in. Maybe it needs some kind of maximal mental exertion test (like a physical VO2 max test) to show up differences consistently.

Re lactate, a series of (small) studies has shown brain lactate levels are higher in CFS patients - here's the most recent one.
Nice post Simon
I'll be blogging on a similar vein on Health Rising in the near future.
Thanks - look forward to reading it.
Thanks Simon. I found planning to be a tough mental task.
I can make great decisions given a set of information in front of me. Long as I don't have to remember anything and apply it at a later time or date
Ta, Jarod. It does seem funny how it affects each of us slightly differently.

Marlène: glad you are so much improved
 
I had huge brainfog, could not even type 3 words or find a bill in a pile some years ago. The names of my children, the road to home, ... it was a disaster. Things have improved since a year. I can write and read a lot. I took a lot of supplements but I guess it is a combination of Low dose naltrexone, licorice root, biotin and D-phenylalaline that did the trick. Biotin in high dosage (10 mg) kills candida and lifts part of the brain fog. Licorice root supports the adrenals and when they start working again (let's say after 9 months of use) it does make a difference. Low dose naltrexone (LDN) is very strong and causes in most people kind of herxheimer reactions for months. You'll have to start very low (0,25 mg for a month before slowly increasing the dose). You produce more endorphines and it had a huge impact on my brain. In the beginning extreme headaches but apparently it was part of my healing. LDN also gives you more energy but it'll affect your sleep in the beginning. Consider 5-HTP of some melatonin to sleep. D-phenylalaline is what is needed to make neurotransmitters. It helps me to be in good mood and apparently to have a better memory as well after extensive usage.
Wish you all the best.
When I get into a crash my brain shuts down almost completely. I can produce words, but the ability to form thoughts ranges from slight (a few sentences worth) to none. Above that, almost nothing -- a simple thought about an immediate condition may stick ("it is time to take prescription x") but after a short time even that fails.
 
I had huge brainfog, could not even type 3 words or find a bill in a pile some years ago. The names of my children, the road to home, ... it was a disaster. Things have improved since a year. I can write and read a lot. I took a lot of supplements but I guess it is a combination of Low dose naltrexone, licorice root, biotin and D-phenylalaline that did the trick. Biotin in high dosage (10 mg) kills candida and lifts part of the brain fog. Licorice root supports the adrenals and when they start working again (let's say after 9 months of use) it does make a difference. Low dose naltrexone (LDN) is very strong and causes in most people kind of herxheimer reactions for months. You'll have to start very low (0,25 mg for a month before slowly increasing the dose). You produce more endorphines and it had a huge impact on my brain. In the beginning extreme headaches but apparently it was part of my healing. LDN also gives you more energy but it'll affect your sleep in the beginning. Consider 5-HTP of some melatonin to sleep. D-phenylalaline is what is needed to make neurotransmitters. It helps me to be in good mood and apparently to have a better memory as well after extensive usage.
Wish you all the best.
When I get into a crash my brain shuts down almost completely. I can produce words, but the ability to form thoughts ranges from slight (a few sentences worth) to none. Above that, almost nothing -- a simple thought about an immediate condition may stick ("it is time to take prescription x") but after a short time even that fails.
I understand. In the beginning of my crash which lasted 14 months, I spent 14 months in a dark room, my brain felt like melting and electricity go haywire. It was awful indeed. Just moving my eyes or a single sound made my brain flip. I was unable to feed myself and only whisper a few words. Thus was in 2008. Things can change, never give up hope.
 
Cognitive problems will be evaluated in CDC multi-clinic study
At the FDA meet on Friday Elizabeth Unger said they would be evaluating cognitive functioning (and exercise performance) in a subset of their 450 subjects. Which could be very interesting as they will have a lot of clinical data they could use to correlate with the cognitive results.
 
I spend a lot of time at work rehearsing what day it is and what treatment room number I have signed out for the shift. Sometimes I go blank on that information and have to start over. I also go totally blank on information I know I know -- like a muscle name I am writing down on a chart. It just leaves. I can visualize what I need to do, but cannot name it or write it down properly, and occasionally have to ask someone. Very embarrassing, but I no longer care, I just ask.
 
Just a few notes. There is quite a bit of objective evidence of slowed information processing in at least subgroups. And Beth Unger did say that some patients showed substantial cognitive issues and others did not so apparently there are subgroups.

Whether or not cognitive issues are found has a great deal to do with not only subgroups, but whether the right instruments were used and how well the person taking the test reflects the norms used. Plus it helps to study the same patients across all studies in meta analysis.

And there are numerous objective and validated ways to prove anomia, acalculia etc.

For example, according to wiki, the Rey-Osterrieth Complex Figure Test (ROCF) is a neuropsychological assessment in which examinees are asked to reproduce a complicated line drawing, first by copying and then from memory. Many different cognitive abilities are needed for a correct performance, and the test therefore permits the evaluation of different functions, such as visuospatial abilities, memory, attention, planning, and working memory (executive functions).

Frank Duffy has found substantial issues in information processing using qEEG.
 
Neuropsychology ???? - it would be great if any answer were there. But to fellow sufferers - hang in there it can slowly clear.
 
I had huge brainfog, could not even type 3 words or find a bill in a pile some years ago. The names of my children, the road to home, ... it was a disaster. Things have improved since a year. I can write and read a lot. I took a lot of supplements but I guess it is a combination of Low dose naltrexone, licorice root, biotin and D-phenylalaline that did the trick. Biotin in high dosage (10 mg) kills candida and lifts part of the brain fog. Licorice root supports the adrenals and when they start working again (let's say after 9 months of use) it does make a difference. Low dose naltrexone (LDN) is very strong and causes in most people kind of herxheimer reactions for months. You'll have to start very low (0,25 mg for a month before slowly increasing the dose). You produce more endorphines and it had a huge impact on my brain. In the beginning extreme headaches but apparently it was part of my healing. LDN also gives you more energy but it'll affect your sleep in the beginning. Consider 5-HTP of some melatonin to sleep. D-phenylalaline is what is needed to make neurotransmitters. It helps me to be in good mood and apparently to have a better memory as well after extensive usage.
Wish you all the best.
When I get into a crash my brain shuts down almost completely. I can produce words, but the ability to form thoughts ranges from slight (a few sentences worth) to none. Above that, almost nothing -- a simple thought about an immediate condition may stick ("it is time to take prescription x") but after a short time even that fails.
I understand. In the beginning of my crash which lasted 14 months, I spent 14 months in a dark room, my brain felt like melting and electricity go haywire. It was awful indeed. Just moving my eyes or a single sound made my brain flip. I was unable to feed myself and only whisper a few words. Thus was in 2008. Things can change, never give up hope.
Wish I could do that. I have to move in about a month, & there's noise where I'm living now, primarily impact noise from stomping/walking in the apt above (the ceiling is attached directly to the beams of the floor above, thin sheetrock, and the ppl above are both over 200#...).

So, gotta move. Can't keep up with stuff... I take most but not all of my meds + can't accurately figure out what to add.

Randomly adding supplements doesn't sit well with me; I broke down and tried one after a persistent insistence by the re who found my current apt. Doc pointed out that it consists of 99+% sugar, a bit of potassium, and a few mg of red wine, grape seed and something else extract. Even if those are beneficial and actually exist in the supplement (you can in practice put anything in a supplement, label it whatever you want and sell it provided no one dies), the amounts are too small to have any effect.

But I also have to try unproven things, as there's no reliable, proven effective medicine for us.
Huh ... how did I type all that? I think bc it was an old, pre-formulated thought. I didn't think that out consciously, it was just words spilling out. Odd... I can't form coherent and on-topic thoughts now, but I can sorta babble via the keyboard.
 
Just a few notes. There is quite a bit of objective evidence of slowed information processing in at least subgroups. And Beth Unger did say that some patients showed substantial cognitive issues and others did not so apparently there are subgroups.
The Beth Unger comment was very interesting, I'd love to see that data in more detail.
...it helps to study the same patients across all studies in meta analysis.
Most of the studies in the meta-analysis used Fukuda or better, though some used Oxford Criteria.

Whether or not cognitive issues are found has a great deal to do with not only subgroups, but whether the right instruments were used and how well the person taking the test reflects the norms used...

And there are numerous objective and validated ways to prove anomia, acalculia etc.

For example, according to wiki, the Rey-Osterrieth Complex Figure Test (ROCF) is a neuropsychological assessment in which examinees are asked to reproduce a complicated line drawing, first by copying and then from memory. Many different cognitive abilities are needed for a correct performance, and the test therefore permits the evaluation of different functions, such as visuospatial abilities, memory, attention, planning, and working memory (executive functions).
It's not necessarily as simple as: find a validated test, run it, get a clean result. There are lots of different validated tests out there and no consensus on the 'right' one to use - and many different ones have been in different CFS studies. However, 4 studies (total 107 patients) in the meta-analysis did use the Rey-Osterrieth Complex Figure Test (ROCF) and found a small-to-moderate deficit relative to controls. However, most other memory tests eg the 'Selective Reminding Test' found larger effects (including some on the same patients).The situation is messy, unfortunately. Seem to be the norm in ME research.

If you want to read the full paper it's worth contacting Susan Cockshell, who I'm sure would provide the full text.
 
Virtual reality games as a better test of real-world cognitive abilities?

Interesting piece at Science Daily about researchers who are trying to develop virtual reality tests of cognitive ability, to get closer to real-world tasks:
Although tests that ask people to do things like solve math problems, sort cards, remember names, or judge the relative positions of lines in visual two dimensional space, can detect cognitive impairments caused by circumscribed lesions following a stroke or head injury, they're not very good at predicting who will be able to function in the real world and who won't.
Their "Multi-tasking in the City" test gets people to go shopping and go the bank is an artificial world: no physical effort is required so it assess how people can cope with the mental demands of those activities.
 
I had huge brainfog, could not even type 3 words or find a bill in a pile some years ago. The names of my children, the road to home, ... it was a disaster. Things have improved since a year. I can write and read a lot. I took a lot of supplements but I guess it is a combination of Low dose naltrexone, licorice root, biotin and D-phenylalaline that did the trick. Biotin in high dosage (10 mg) kills candida and lifts part of the brain fog. Licorice root supports the adrenals and when they start working again (let's say after 9 months of use) it does make a difference. Low dose naltrexone (LDN) is very strong and causes in most people kind of herxheimer reactions for months. You'll have to start very low (0,25 mg for a month before slowly increasing the dose). You produce more endorphines and it had a huge impact on my brain. In the beginning extreme headaches but apparently it was part of my healing. LDN also gives you more energy but it'll affect your sleep in the beginning. Consider 5-HTP of some melatonin to sleep. D-phenylalaline is what is needed to make neurotransmitters. It helps me to be in good mood and apparently to have a better memory as well after extensive usage.
Wish you all the best.
When I get into a crash my brain shuts down almost completely. I can produce words, but the ability to form thoughts ranges from slight (a few sentences worth) to none. Above that, almost nothing -- a simple thought about an immediate condition may stick ("it is time to take prescription x") but after a short time even that fails.
I understand. In the beginning of my crash which lasted 14 months, I spent 14 months in a dark room, my brain felt like melting and electricity go haywire. It was awful indeed. Just moving my eyes or a single sound made my brain flip. I was unable to feed myself and only whisper a few words. Thus was in 2008. Things can change, never give up hope.
Wish I could do that. I have to move in about a month, & there's noise where I'm living now, primarily impact noise from stomping/walking in the apt above (the ceiling is attached directly to the beams of the floor above, thin sheetrock, and the ppl above are both over 200#...).

So, gotta move. Can't keep up with stuff... I take most but not all of my meds + can't accurately figure out what to add.

Randomly adding supplements doesn't sit well with me; I broke down and tried one after a persistent insistence by the re who found my current apt. Doc pointed out that it consists of 99+% sugar, a bit of potassium, and a few mg of red wine, grape seed and something else extract. Even if those are beneficial and actually exist in the supplement (you can in practice put anything in a supplement, label it whatever you want and sell it provided no one dies), the amounts are too small to have any effect.

But I also have to try unproven things, as there's no reliable, proven effective medicine for us.
Huh ... how did I type all that? I think bc it was an old, pre-formulated thought. I didn't think that out consciously, it was just words spilling out. Odd... I can't form coherent and on-topic thoughts now, but I can sorta babble via the keyboard.
Totally understand this. I either don't talk or type then go into loads of typing and talking which is really just a brain dump.....it happens when i get into a wired tired state. Staying on-topic is hard but grammar and most spelling remains intact. So of course people tell me I have no problems with communication when i struggle to write a shopping list without assistance.
 
I think a real meaningful study would compare the CFS patients to their former healthier selves rather than to "controls". I don't mean to brag but I know I had a high IQ back when I was healthier. I suspect that my IQ is probably lower now and more in the average range so compared to controls there wouldn't be much of a difference. But if you compare ME now to the ME I used to be -- big difference!

Also, due to adrenaline, if I knew I was being tested for cognitive function I would perform a lot better than when I'm relaxed and complacent at home.