Post-exertional malaise in veterans with gulf war illness, 2019, Lindheimer Cook et al

https://www.sciencedirect.com/science/article/abs/pii/S0167876019305495

 

I have not read the paper yet, but it seems to me that this paper may just raise questions, not provide answers. GWI also does not have a definitive test. Is it really ME in these patients? Or is PEM not unique to ME? Or do these patients have both ME and GWI? Or is there yet another explanation?

 

Endorsing "feeling unwell after physical exercise or exertion" seems vague.

We do not have a validated questionnaire designed to identify PEM and it would have been useful here.

 

24 hours is not peak PEM for us.
How and what was measured?
Questionnaires or something objective?

 

Like calling migraines a slight headache with minor discomfort.

Poor definitions and reliance on dubious questionnaires does not help much to answer questions. I don't think it really ever was suggested PEM was notable in GWI other than comparisons to ME. "Endorsers" is weird typical "patient thinks" framing. It talks of perception of pain and fatigue but when the questions are aligned to fit with researchers' expectations it's always "fatigue was reduced". It's perception when it increases and it's real and significant when it decreases.

Not impressed. The researchers involved have a poor grasp of PEM and biased expectations.

 

Cook (one of the authors) did this study on ME/CFS in 2017.
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Neural consequences of post-exertion malaise in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
Cook DB, et al. Brain Behav Immun. 2017.
Show full citation
Abstract
Post exertion malaise is one of the most debilitating aspects of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, yet the neurobiological consequences are largely unexplored. The objective of the study was to determine the neural consequences of acute exercise using functional brain imaging. Fifteen female Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients and 15 healthy female controls completed 30min of submaximal exercise (70% of peak heart rate) on a cycle ergometer. Symptom assessments (e.g. fatigue, pain, mood) and brain imaging data were collected one week prior to and 24h following exercise. Functional brain images were obtained during performance of: 1) a fatiguing cognitive task - the Paced Auditory Serial Addition Task, 2) a non-fatiguing cognitive task - simple number recognition, and 3) a non-fatiguing motor task - finger tapping. Symptom and exercise data were analyzed using independent samples t-tests. Cognitive performance data were analyzed using mixed-model analysis of variance with repeated measures. Brain responses to fatiguing and non-fatiguing tasks were analyzed using linear mixed effects with cluster-wise (101-voxels) alpha of 0.05. Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients reported large symptom changes compared to controls (effect size ≥0.8, p<0.05). Patients and controls had similar physiological responses to exercise (p>0.05). However, patients exercised at significantly lower Watts and reported greater exertion and leg muscle pain (p<0.05). For cognitive performance, a significant Group by Time interaction (p<0.05), demonstrated pre- to post-exercise improvements for controls and worsening for patients. Brain responses to finger tapping did not differ between groups at either time point. During number recognition, controls exhibited greater brain activity (p<0.05) in the posterior cingulate cortex, but only for the pre-exercise scan. For the Paced Serial Auditory Addition Task, there was a significant Group by Time interaction (p<0.05) with patients exhibiting increased brain activity from pre- to post-exercise compared to controls bilaterally for inferior and superior parietal and cingulate cortices. Changes in brain activity were significantly related to symptoms for patients (p<0.05). Acute exercise exacerbated symptoms, impaired cognitive performance and affected brain function in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome patients. These converging results, linking symptom exacerbation with brain function, provide objective evidence of the detrimental neurophysiological effects of post-exertion malaise.

Published by Elsevier Inc.
PMID
28216087 [Indexed for MEDLINE]

 

I don't think they are distinguishing post exertional fatigue from post exertional malaise. I have thought about this and I experience problems immediately with exercise beyond my limits which seems to e what they are looking at here, but the true unique post exertional malaise of ME is delayed and prolonged.

I just rarely get the fatigue part because I pace myself and know my limits. PEM creeps up on me

 

Easier to read abstract

Scihub link, https://sci-hub.se/10.1016/j.ijpsycho.2019.11.008

 

Your questions seem particularly pertinent in view of this sentence in the conclusions:

Impressions after a quick skim only:
They do seem to understand PEM in ME.
They are very vague in their definition of PEM in GWI.
PEM, even by their vague definition, is much less of an issue in GWI in this study than in ME - which to my mind does raise the question do the minority who do have PEM really have ME (instead or as well as)?
The authors call for a better definition and operationalisation of PEM. Yes to that.

 

Seems interesting.

Less than half of patients with gulf war illness agreed with the statement "feeling unwell after physical exercise or exertion". And there were no group by time difference in symptoms after the exercise test for the whole sample. That would seem to suggest a difference with ME/CFS. The paper writes: "In the present study, PEM responses were clearly not as robust as seen in the ME/CFS literature." It seems that the authors had not expected this result.

 

Does this then relate to the postulated TH1 v TH2 immune response difference between GWI and ME ?

If so could it hone in on the " something in the blood" ?