Fibromyalgia and ME/CFS: an interoceptive predictive coding model of pain and fatigue expression, 2021, Sharp et al

1. Harriet Sharp1,2,
2. Kristy Themelis1,3,
3. Marisa Amato1,
4. Andrew Barritt1,
5. Kevin Davies1,
6. Neil Harrison1,4,
7. Sarah Garfinkel1,5,
8. Hugo Critchley1,2,
9. Jessica Eccles1,2

Abstract:

Introduction: The aetiology and pathophysiology of fibromyalgia and ME/CFS are poorly characterised but altered inflammatory, autonomic and interoceptive processes have been implicated. Interoception has been conceptualised as a predictive coding process; where top-down prediction signals compare to bottom-up afferents, resulting in prediction error signals indicating mismatch between expected and actual bodily states. Chronic dyshomeostasis and elevated interoceptive prediction error signals have been theorised to contribute to the expression of pain and fatigue in fibromyalgia and ME/CFS.

Objectives/Aims: To investigate how altered interoception and prediction error relates to baseline expression of pain and fatigue in fibromyalgia and ME/CFS and in response to an inflammatory challenge.

Methods: Sixty-five patients with fibromyalgia and/or ME/CFS diagnosis and 26 matched controls underwent baseline assessment: self-report questionnaires assessing subjective pain and fatigue and objective measurements of pressure-pain thresholds. Participants received injections of typhoid (inflammatory challenge) or saline (placebo) in a randomised, double-blind, crossover design, then completed heartbeat tracking task (assessing interoceptive accuracy). Porges Body Questionnaire assessed interoceptive sensibility. Interoceptive prediction error (IPE) was calculated as discrepancy between objective accuracy and subjective sensibility.

Results: Patients with fibromyalgia and ME/CFS had significantly higher IPE (suggesting tendency to over-estimate interoceptive ability) and interoceptive sensibility, despite no differences in interoceptive accuracy. IPE and sensibility correlated positively with all self-report fatigue and pain measures, and negatively with pain thresholds. Following inflammatory challenge, IPE correlated negatively with the mismatch between subjective and objective measures of pain induced by inflammation.

Conclusions: This is the first study to reveal altered interoception processes in patients with fibromyalgia and ME/CFS, who are known to have dysregulated autonomic function. Notably, we found elevated IPE in patients, correlating with their subjective experiences of pain and fatigue. We hypothesise a predictive coding model, where mismatch between expected and actual internal bodily states (linked to autonomic dysregulation) results in prediction error signalling which could be metacognitively interpreted as chronic pain and fatigue. Our results demonstrate potential for further exploration of interoceptive processing in patients with fibromyalgia and ME/CFS, aiding understanding of these poorly defined conditions and providing potential new targets for diagnostic and therapeutic intervention.

https://jnnp.bmj.com/content/92/8/A3.3

 

Why would one assume that the ability of patients to accurately count their heart beats tells us anything about the cause of pain and fatigue?

When I count my heart beat, I rely on touch and sound. It doesn't seem likely that the relevant portions of the brain also rely on touch and sound.

 

What is this computer-jargon have to do with the not well-elucidated brain modulatory process, and call it top-down prediction signals when obviously in fibromyalgia, the huge amount of sensory (afferent) nerve input to the brain is off the charts?

"Interoception has been conceptualised as a predictive coding process; where top-down prediction signals thcompare to bottom-up afferents, resulting in prediction error signals indicating mismatch between expected and actual bodily states. Chronic dyshomeostasis and elevated interoceptive prediction error signals have been theorised to contribute to the expression of pain and fatigue in fibromyalgia and ME/CFS..."

This is just so much fluff.

 

If this is the first, how can the introduction list it as having "been implicated"? If this is the first, the citation for the presence of "altered interoception" would be... itself. It's a recursive citation. Because this whole field is a parody of bad science.

And many things have been conceptualized, it literally means nothing. Cthulhu has been conceptualized. What a bunch of juvenile nonsense.

 

He has moved to Cardiff Uni.
He spoke at an AfME AGM where he was showing slides of brain activity. (Do not have notes to hand re type of imaging etc). I chatted with him afterwards, briefly before he left for his train, as he spoke of increased activity in the basal ganglia.
My daughter was found to have autoantibodies to the pyruvate kinase receptors in the basal ganglia. He was surprised that I'd noticed that only one of the basal ganglia showed this effect, but did not know why this had occurred.