Metacognitive Performance on Memory and Visuospatial Tasks in Functional Cognitive Disorder, 2021, Pennington et al

Abstract

Functional Cognitive Disorder (FCD) is a common diagnosis at the memory clinic. FCD is characterised by significant self-reported cognitive symptoms in the absence of external evidence of cognitive dysfunction. A potential explanation for this is a deficit in metacognition, the process by which we internally judge our own abilities.

Here we investigated differences in accuracy, confidence, and metacognition between people with FCD (N = 20), neurodegenerative mild cognitive impairment (nMCI; N = 14), and healthy controls (N = 23). The groups were assessed on forced choice memory and perceptual tasks, with trial by trial confidence ratings. FCD and nMCI participants showed lower accuracy on the memory task (means FCD 63.65%, nMCI 63.96%, HC 71.22%), with a significant difference between the FCD and HC groups after controlling for age and sex. There were no between-group differences in memory task confidence (means FCD 3.19, nMCI 3.59, HC 3.71). The FCD group showed greater confidence when longer time was allowed on the memory task. No between group differences in perceptual task accuracy (means FCD 63.97%, nMCI 64.50%, FCD 65.86%) or confidence (means FCD 3.71, nMCI 3.43, HC 3.88) were found. No differences in metacognitive efficacy emerged between the groups, either on the memory or perceptual task (Memory Meta-d’/d’:FCD 0.63, nMCI 0.94 HC 0.85; Perceptual Meta-d’,d’: FCD 0.50, nMCI 0.51, HC 0.72). Participants showed greater metacognitive efficacy on the memory task compared to the perceptual task.

The difficulties experienced by people with FCD do not appear to be due to metacognitive deficits. Their performance was similar to people with nMCI over aspects of the memory tasks, which suggests that the primary issue may lie with memory encoding or retrieval, rather than with their judgement of performance accuracy.

Open access, https://www.mdpi.com/2076-3425/11/10/1368/htm

 

I hope this study ends some of the bullshit hypotheses associated with FCD...

 

It's funny how the neurologists get the cognitive stuff completely backwards. My experience is that i'm very aware of how my brain is not working, and i can tell when it's making errors due to the cognitive impairment. It's like i know exactly how my brain should work, how the circuits should fire, i just can't get it to work no matter what. I suppose this is unusual in neurology, because typically in dementias the patient awareness also gradually decreases as the illness gets worse. Not only they keep making more mistakes as the illness worsens, their ability to be aware of their mistakes also gradually decreases to the point where their consciousness sort of fades away. But it seems that in ME/CFS, no matter how severe the cognitive impairment gets, that awareness always remains there. It's just the the brain is sort of frozen in a way.

Somehow, from this neurologists must deduce that the brain works perfectly fine and the problem is just that the patient thinks they have cognitive impairment when they really don't. My speculation is that this is because neurologists are taught that this lack of awereness that i described is precisely the core symptom of cognitive impairment, and without it there cannot be any. This is what 99% of neurologists think. I doubt one study (or even 10, or even 100) will change this belief anytime soon.

 

To be fair there are many other situations where people with cognitive impairments are very aware of their own deficits, and it is not uncommon for people with dementias, at least in the early stages to have insight into their problems.

 

Then what is the discriminating factor? I've seen people with dementias in the early stage that don't have measurable deficits in neuropsychological tests. But they are taken seriously by doctors. Why? How can they tell that they are different? One could say the difference is that they don't complain about fatigue but I've tried not complaining about fatigue to neurologists and they still "sniff" me out. My assumption was that they can somehow tell a dementia patient is less aware (even if only slightly, if the illness is in the early stages) but maybe i'm totally wrong.

 

[Sorry This is too long and confused, but I am not with it enough today to rewrite it in a more easily understood form.]

There is enormous variation between people with dementia as to how aware they are of their problems. One difference I would use as a possible indicator in differential diagnosis between dementia and aphasia (language problems following focal brain damage) was that the former often tried to hide their deficits while the latter were desperate for an answer. However this is not always so cut and dry. My aunt was an extreme, she developed many effective coping strategies to deal with her Alzheimer’s: she also informed people about it, got them to write in her visitors’ diary, kept an elaborate calendar and an annotated photo album for any new people. When, in their 90s she and my uncle decided to leave their large family home of nearly 70 years, visiting flats, my aunt provided her husband an daughter a verbal summary of how she felt about each flat they looked at while they where there. At the one they eventually chose, she said “as soon as we go out if the door I will forget this flat, but tell me I said this is the one I want to move to”.

Me feeling is that given enormous personal variation between individuals any studies in the effects of health on cognition require either premorbid baseline test results, which, though potentially possible in such as a prospective study of Covid, are more generally unobtainable without a time machine, or require large enough subject cohorts such that your groups can be said to be representative of whole populations. I would not expect in groups of 20 or 14 to allow robust generalisations to entire populations. Also how do you match the FCD group to normal controls without things like their pre morbid IQ, their reading age, their education level, their reasoning skills and strategies. What if one was a master yogi, another a professional classical dance or another a chess master? For example in a small group looking at the effect of Covid 19 on taste, your results could be grossly thrown out if you happened to drop a professional tea taster, perfumer and a sommelier into the mix? The only way round this is to use such large groups that within group variation becomes irrelevant compared to between group variation.

Also there are many cognitive issues such as short term memory, word finding, attention span, that are not reliable diagnostic tools in identifying specific disorders. They are generally very variable both within and between individuals with the same diagnostic category and are present in a number of very different diagnostic groups. Also performance can be tied to many factors such as tiredness, alertness, confidence, etc for those that have mild or moderate impairments in this task.

Variability is a big factor for the true believers in functional issues, and the ability to do a task in one context but not another is a red flag for them in deciding a functional diagnosis. This is unfortunate as that same variability can be seen in those with an unambiguous neurological diagnosis. I often cite the example of an aphasia patient whose reading and spelling skills were assessed by myself and then other neuropsychologists over several years. He was quite capable of struggling to read the word ‘gauge’, then turn his head to an observer and say clearly “Gauge is one of those words I can never read aloud” then return back to the task still unable to read the word gauge. This insight and inconsistency was very consistent with his acquired reading deficient and having been a well studied subject developing insight into his disorder, but to a true believer this would be incontrovertible evidence for a function neurological disorder.

Also in relation to any skill levels this is very relevant to understanding within subject variation under different circumstances. For example, a good amateur pianist may perform as well as a professional on a simple musical task such as playing scales in a practice room, but fail by comparison when asked to sight read a complex symphony with a full orchestra in front of a large audience. Would you then assert that the amateur had a music related functional neurological disorder?