Distinctive body perception mechanisms in high versus low symptom reporters: A neurophysiological model for [MUS], 2020, Schulz et al

Andy · Sep 1, 2020

Full title: Distinctive body perception mechanisms in high versus low symptom reporters: A neurophysiological model for medically-unexplained symptoms

Objective
The neurophysiological processes involved in the generation of medically-unexplained symptoms (MUS) remain unclear. This study tested three assumptions of the perception-filter model contributing to MUS: (I.) increased bodily signal strength (II.) decreased filter function, (III.) increased perception.

Methods
In this cross-sectional, observational study, trait MUS were assessed by a web-based survey (N = 486). The upper and lower decile were identified as extreme groups of high (HSR; n = 29; 26 women; Mage = 26.0 years) and low symptom reporters (LSR; n = 29; 21 women; Mage = 28.4 years). Mean heart rate (HR) and heart rate variability (HRV), and cortisol awakening response (CAR) were assessed as indicators of bodily signal strength (I.). Heartbeat-evoked potentials (HEPs) were assessed during rest and a heartbeat perception task. HEPs reflect attentional resources allocated towards heartbeats and served as index of filter function (II.). Interoceptive accuracy (IAc) in heartbeat perception was assessed as an indicator of perception (III.).

Results
HSR showed higher HR and lower HRV (RMSSD) than LSR (I.), but no differences in CAR. HSR exhibited a stronger increase of HEPs when attention was focused on heartbeats than LSR (II.); there were no group differences in IAc (III.).

Conclusions
The perception-filter model was partially confirmed in that HSR showed altered bodily signals suggesting higher sympathetic activity (I.); higher HEP increases indicated increased filter function for bodily signals (II.). As more attentional resources are mobilized to process heartbeats, but perception accuracy remains unchanged (III.), this overflow could be responsible for detecting minor bodily changes associated with MUS.
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Open access, https://www.sciencedirect.com/science/article/pii/S0022399920307856

Snow Leopard · Sep 1, 2020

The Goal of this study was to test the "perception-filter model" of medically unexplained symptoms (MUS) in "persistent somatic symptom disorder" (SSD)

Shulz et al. 2020 said:

Theories addressing the underlying neurophysiology of SSDs are scarce. The seminal perception-filter model [12,13] is one exception. This model posits that the generation of MUS consists of three stages: (I.) amplified (afferent) bodily signals as a consequence of autonomic over-arousal [14,15], activation of the immune system [16,17] or the HPA axis [18], (II.) decreased filter system activity [19,20], leading to poor differentiation of relevant bodily signals (e.g., hunger, thirst) from background noise, and (III.) increased perception of bodily signals and/or symptoms.
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Shulz et al. 2020 said:

With regard to bodily signals (stage I.), we found higher HR and lower HRV (RMSSD) in HSR than in LSR individuals, suggesting higher cardiac activation in MUS, possibly mediated by lower parasympathetic and higher sympathetic tone (supporting hypothesis i). Concerning filter system activity (stage II.), HSR individuals showed stronger reactivity of HEPs to attention focused on heartbeats (during a heartbeat counting task) than LSR individuals (in contrast to hypothesis ii). Current evidence primarily focuses on stage (III.), i.e. perception. According to the perception-filter model, interoception, i.e. the perception of bodily signals, plays an important role for MUS. In the current study, there were no IAc differences between groups, suggesting that perception of cardiac signals is not altered in HSR individuals (in contrast to hypothesis iii), despite the differences in stages I. and II. Finally, correlation analyses showed that indicators of bodily signals are related to both filter system activity and perception, whereas no relationship was found between filter system activity and perception. In summary, the assumptions of the perception-filter model could only partially be supported with heartbeats as bodily signal. While changes in bodily signals in individuals with MUS could be confirmed, the results concerning alterations of the filter system were opposed to expectations. Concerning perception, there were no differences. We would argue, therefore, that the role of the filter system and that of perception for MUS have to be reconsidered in the context of the perception-filter model.
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So while participants reporting a higher level of symptoms did have higher heart rates and lower heart rate variation, this was not due to increased HPA axis activity, nor decreased filter system activity, nor increased perception of bodily symptoms. The authors merely assume the increased heart rate/HRV implies higher sympathetic activity and assume this implies increased "arousal". However this assumption is not justified given the data. These parameters can reflect reduced parasympathetic activity, rather than increased sympathetic activity. Direct parameters such as catecholamines or neurological measurements were not taken. These parameters also tend to be associated with a lack of cardiovascular fitness and thus the association may be indirect - participants with more symptoms may simply be less inclined to participate in intense physical activity.

Overall, this study suggests the "perception-filter model" of MUS is false.

rvallee · Sep 1, 2020

Complete nonsense. The conclusion is a total fantasy. What the hell does "processing heartbeats" even mean? It's a fully autonomic process. These people are out of their damned minds, playing with lives like they mean absolutely nothing.

Mean heart rate (HR) and heart rate variability (HRV), and cortisol awakening response (CAR) were assessed as indicators of bodily signal strength (I.)
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You can't just take random things and decide they are relevant. This is exactly as arbitrary as the freaking Thetan-reading machine in Scientology. Complete failure of oversight to allow this garbage.

Booo. Boooooooooooooooooooooooooo.

Arnie Pye · Sep 1, 2020

This study tested three assumptions of the perception-filter model contributing to MUS: (I.) increased bodily signal strength (II.) decreased filter function, (III.) increased perception.
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I notice that one assumption they don't mention is that only females suffer from the pointless crap they are "investigating".

alktipping · Sep 2, 2020

why exactly would anyone take the term medically unexsplained and try to turn it into a syndrome the stupidity of this field is truly baffling.

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Distinctive body perception mechanisms in high versus low symptom reporters: A neurophysiological model for [MUS], 2020, Schulz et al

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Distinctive body perception mechanisms in high versus low symptom reporters: A neurophysiological model for [MUS], 2020, Schulz et al

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