Autonomic, Endocrine, and Inflammation Profiles in Functional Neurological Disorder: A Systematic Review and Meta-Analysis, 2021, Perez et al

Abstract

Objective:
Functional neurological disorder (FND) is a core neuropsychiatric condition. To date, promising yet inconsistently identified neural circuit profiles have been observed in patients with FND, suggesting that gaps remain in our systems-level neurobiological understanding. As such, other important physiological variables, including autonomic, endocrine, and inflammation findings, need to be contextualized for a more complete mechanistic picture.

Methods:
The investigators conducted a systematic review and meta-analysis of available case-control and cohort studies of FND. PubMed, PsycINFO, and Embase databases were searched for studies from January 1, 1900, to September 1, 2020, that investigated autonomic, endocrine, and inflammation markers in patients with FND. Sixty-six of 2,056 screened records were included in the review, representing 1,699 patients; data from 20 articles were used in the meta-analysis.

Results:
Findings revealed that children and adolescents with FND, compared with healthy control subjects (HCs), have increased resting heart rate (HR); there is also a tendency toward reduced resting HR variability in patients with FND across the lifespan compared with HCs. In adults, peri-ictal HR differentiated patients with functional seizures from those with epileptic seizures. Other autonomic and endocrine profiles for patients with FND were heterogeneous, with several studies highlighting the importance of individual differences.

Conclusions:
Inflammation research in FND remains in its early stages. Moving forward, there is a need for the use of larger sample sizes to consider the complex interplay between functional neurological symptoms and behavioral, psychological, autonomic, endocrine, inflammation, neuroimaging, and epigenetic/genetic data. More research is also needed to determine whether FND is mechanistically (and etiologically) similar or distinct across phenotypes.

Paywall, https://neuro.psychiatryonline.org/doi/10.1176/appi.neuropsych.21010025

 

And of course physiological findings could also be indicative of undiagnosed biomedical conditions, but if your subject group is heterogenous, possible containing a variety of undiagnosed other conditions, such studies are unlikely to find consistent group patterns.

 

So hunting for physiological abnormalities to prove the condition is psychological?

Imagine leaving these people under a psych umbrella if physiological abnormalities are found.

And, as @Sean says, FND is a non-existent category.

 

Resting heart rate and heart rate variability are very non-specific markers and are usually just an indication of lower fitness and activity levels.

 

Fictional neurological disorder.

 

Oooh I like this.

 

The only problem I have is the description of FND as neuropsychiatric…
It seems to me, unless i am reading it all wrong, that this paper is a good thing. Looking for biological clues for neurological difficulties.

 

In most instances investigations like this would be great, but what the FND crowd do is take any sign of biological abnormality and then hold that up as evidence for their FND construct, rather than attempting to consider whether that abnormality might actually offer an alternative, more credible, explanation for the patients symptoms.

 

Yes, every study they do is confirmation of their beliefs with no room for any alternative explanations because CBT and physio is the cure (except for people whose behaviour is "entrenched")

 

I see what @Daisybell is getting at though. If these researchers do good research (but in bad faith) then the research findings are still valid and can be viewed as such by others who might find some tantilising clue to some biological finding. Or not.

The Fictional neuro disorder people are gonna keep their fiction alive regardless. The real question is do they have what it takes to do any real biological research or are they just playing with their toys hoping to create some new biological framework for what they already know.

I think if we want to get to the core of this shiny new thing then we might want to look more closely at central sensitisation. What does that mean theoretically / biologically, what's the proof, etc.

 

IS FND not undergoing a reappraisal ? This page from a respected institution https://www.ninds.nih.gov/Disorders...on/Fact-Sheets/Functional-Neurologic-Disorder is specific in saying FND is an organic condition, acknowledges that the name came from Freud but explains it is physical in nature.

Edit to add a piece from the bio of the last named author:

https://www.massgeneral.org/doctors/19542/david-perez

 

I don't see evidence of that in the studies that I come across. Sure, they pay lip service to that idea, but it still comes down to mind over matter theories, and if patients just changed how their thinking then they would magically get better.

 

If that statement turns out to be face value than I suppose that could be good (I'm writing without the benefit of having taken some time to think first).

But . . . I do not trust this area of endeavour at the moment. I have my reasons. Language has proved to be a more slippery a more disingenuous thing than the desire to clearly communicate honestly. A rather unfortunate evolution of the use of language in my opinion.

Edit: typos

 

Recent papers still say that FND is the new name for conversion disorder. I suspect that they now believe they have found the organic pathology behind hysteria. It always existed but now they have proof it genuinely exists alongside neurological diseases.

This gels with the way they claim that CBT changes the grey matter of the brain and that they have found the damaged regions of the brain which make someone get FND if they have a psychological problems. And still treatable with CBT

It is just adding a layer of complexity to brain damage.