Brain fog of post-COVID-19 condition and Chronic Fatigue Syndrome, same medical disorder? 2022 Azcue et al

Abstract

Background
Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is characterized by persistent physical and mental fatigue. The post-COVID-19 condition patients refer physical fatigue and cognitive impairment sequelae. Given the similarity between both conditions, could it be the same pathology with a different precipitating factor?

Objective
To describe the cognitive impairment, neuropsychiatric symptoms, and general symptomatology in both groups, to find out if it is the same pathology. As well as verify if the affectation of smell is related to cognitive deterioration in patients with post-COVID-19 condition.

Methods
The sample included 42 ME/CFS and 73 post-COVID-19 condition patients. Fatigue, sleep quality, anxiety and depressive symptoms, the frequency and severity of different symptoms, olfactory function and a wide range of cognitive domains were evaluated.

Results
Both syndromes are characterized by excessive physical fatigue, sleep problems and myalgia. Sustained attention and processing speed were impaired in 83.3% and 52.4% of ME/CFS patients while in post-COVID-19 condition were impaired in 56.2% and 41.4% of patients, respectively. Statistically significant differences were found in sustained attention and visuospatial ability, being the ME/CFS group who presented the worst performance. Physical problems and mood issues were the main variables correlating with cognitive performance in post-COVID-19 patients, while in ME/CFS it was anxiety symptoms and physical fatigue.

Conclusions
The symptomatology and cognitive patterns were similar in both groups, with greater impairment in ME/CFS. This disease is characterized by greater physical and neuropsychiatric problems compared to post-COVID-19 condition. Likewise, we also propose the relevance of prolonged hyposmia as a possible marker of cognitive deterioration in patients with post-COVID-19.

Open access, https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-022-03764-2

 

Accidentally accurate

But otherwise this paper is mostly an annoying missed opportunity. We do need to have a really good, deep look at the various flavours of brain fog. But I'm not sure this study tells us much. Yes, they came up with some evidence for some cognitive deficits and I guess that's something.

But really it looks more like a fishing expedition. They ran a vast number of cognitive and psychological assessments of mixed appropriateness and came up with approximately 517 correlations. I may very well have missed something but if those 539 correlations didn't quite make me lose the will to live they sure made me lose the will to read the paper carefully. Or maybe that was just my ME-induced trouble with sustained attention?

The fact they used Fukuda didn't help my motivation to spend energy on checking if anything useful could be salvaged from the data, nor did this conclusion

As I said, I ended up just skimming the paper and may have missed the point. The MEA article linked in the previous post calls it an important paper but that seems to be based on the authors having referenced some MEA material and on that the study found symptom overlap between ME and LC. Well yes, but... so what?

 

Charles Shepherd is referenced at the bottom of the article, implying he is the author of the commentary.

 

Frustrating to see this myth repeated:

"In addition, they usually present psychopathological symptoms [10, 14], independently of cognitive performance [10, 15], among which depressive and anxious symptoms stand out [10, 14, 15]."

Multiple studies have failed to find a relationship between ME/CFS patients' symptoms of distress and strain and cognitive issues and deficits. Peer review should have picked this up. I suspect the paper was reviewed by people with no specific experience of neuropsychological testing in pwME.

And the symptoms of distress patients understandably report due to debility, isolation and so forth due primarily due to their ME cannot be disentangle by questionnaires. This needs detailed structured clinical interview, assessment and review in conjunction with the patient. Using questionnaires on their own will likely overestimate low mood and stress symptoms. Disappointing. Missed opportunity. This might have been done to reduce time/effort burden on patients. But if this leads to poor quality data that misleads then this was a mistaken decision. Patients want difficulties explained well and in context. That is not possible from questionnaire responses. Basic error.

 

Using the Montreal Cognitive Assessment (MoCA) covers a lot of areas that impact pwME; however, key tests that are the most effective at highlighting the cognitive issues pwME face, such as PASAT, are not part of this battery of tests. I'm not familiar with this specific battery, though I am familiar with many of the individual tests used, so I'm not sure it's intended use. I shall have a wee look.

Most batteries of neuropsychology tests are set up to assess the impact of neurodevelopmental disorders, which ME is not.

In general the tests that are most appropriate with pwME are those aimed at those assessing brain injury and recovery, for example, effects and recovery from concussion.

 

Frustrating that they did not include a healthy control group. Missed opportunity

 

"Education, physical problems, pain, fatigue, sleep quality, depressive symptoms, anxiety and suicidal ideation, largely explained the variance of the cognitive deficits found in both groups,...."

So pretty much anything in the kitchen sink. Cannot see meaning in this type of analysis.

 

"In the case of ME/CFS, the level of functionality was mostly related to physical capacity, pain and anxiety. Therefore, pain reduction and physical recovery should be objective variables in these populations, ***trying to avoid a sedentary lifestyle that can produce greater physical deconditioning.****"
OK so they really don't 'get it' missed opportunity. They do mention PEM within the work, but not as a major symptom.


"Both anxious and depressive symptoms should be evaluated and treated in both conditions, since both are closely related to suicidal ideation [42,43,44]."
Sure, that's an obvious thing to state but if that is linked to the previous sentence they will have limited success and potentially do harm. Out of date. Also, they don't define how this will be evaluated, for example, via structured clinical interview etc which is necessary to not overestimate emotional symptoms. And if patients do not have distress such as those without extensive physical symptoms then the evidence base is minimal. Their conclusions here could mislead in this regard. The majority of pwME do not meet criteria for MDD, GAD etc. They are understandably pissed off, demoralised etc. And understandably strained due to incredibly debilitating medical condition, multiple losses, financial pressures and lack of practical support. That cannot be assessed via a questionnaire

 

From Hutan

"We so need research to be better than this, and we need influential patient charities to be pushing for that better research, not applauding rubbish."

My reading of the MEA comments is they were done quickly in a bit of a rush. I don't think they pinged the deconditioning link the authors make in the discussion, for example. The are good parts to this paper, for example, the high level of impairments across multiple cognitive domains but there are many lost opportunities.

 

Final comment: Why use the term "Brain fog" and especially in the title? I doubt clinicians or researchers would refer to the 'brain fog' in patients with TBI. Maybe they want to mirror and use terms patients use, but this is not discussed in the paper. Why not use the conventional, professional language in a professional paper?

Patients frequently state that the neuropsychological symptoms are some of the worst to manage and the most debilitating. This is frequent in the literature regarding ME. And this paper has highlighted a lot of impairment (which has specific and significant) meaning in neuropsychological testing.

 

As discussed here, From academic success to cognitive disability