Anti-ganglionic acetylcholine receptor antibodies in functional neurological symptom disorder/conversion disorder, 2023, Nagata et al

What if ME and FND could have similar pathologies? Perhaps FND causes mostly overt neurological symptoms because the pathology only affects specific regions of the brain, where ME affects more of the brain and causes problems in other parts of the body.

 

The conversion disorder stuff simply appears to be stacked on because reasons. Criteria were for neurological symptoms and a lack of diagnosis, it's just that the DSM criteria for "conversion disorder" are circular and basically apply to everyone with a neurological condition, the only exemption being a diagnostic. You could basically label this "not blessed by a medical priest" for all that it's relevant.

So basically, those are people with mostly dysautonomia. Shows how blatantly useless the FND labeling is. At this point, it's probably reasonable to think this is simply because FND is very marketable and will give the paper more prominence, but you could just as well apply criteria for demonic possession, or whatever.

Reading the symptoms list, huge overlap with ME. This may actually be somewhat relevant, despite the unnecessary marketing element. For sure this could be some LC cohort with some arbitrary criteria. Damn is medicine arbitrary when they don't have the biology nailed down, just all over the place with no concern for coherence or validity.

Invariably, when I see discussion in the wild about FND that finds anything biological, you will find a form of this reply: "so, it's not functional, then?" By which of course they all mean the magical generation of any and all symptoms by way of some imagined emotional distress that actually only means "not gonna bother with you". Or whatever.

 

There's something with this tweet I have been wanting to ask on the 'basic questions on research metholodolgy' thread for a while now -- even if it's more about language/ wording of study reports.

I wonder which is a large enough sample to report in percentages instead of natural numbers.

To me percentages, at a first glance, always appear to report representative figures.

I find it misleading to report only percentages in the abstract if you have a sample that's not large enough to be representative.

To be fair, the quoted paper does report the total number (and reports the subgroups in natural numbers) in the abstract and reads less spectacular than the Tweet. I think the Tweet is also misleading as the important info that the whole sample were patients with a FND diagnosis is postponed. I first read it as 88 percent of all patients in a neurological clinic not 88 percent of patients diagnosed with FND.

So of 59 patients diagnosed with FND in a particular neurological department the sample was taken from, 52 patients "exhibited autonomic disturbances" and 16 patients had anti-gAChR antibodies.


Paper's abstract:

Edited to add:

The author's conclusion in the paper:

"More than 80% of our FNSD/CD patient cohort had autonomic symptoms, and more than 25% of the cohort were positive for serum anti-gAChR antibodies, whether or not autonomic symptoms were present.

"To clarify the relationship between this psychiatric disorder and anti-gAChR antibodies, further investigation of clinical symptoms and the establishment of a measurement system for antibodies against the anti-nAChR subunit are needed."

 

Which is an important finding when the formulation of FND, as secured by positive rule-in signs, means that there should be no further medical tests - and that doing more tests is both an unnecessary waste of scarce resources and will undermine the patient's recovery.

 

Yes, @Sean and @SNT Gatchaman --

Even if only one patient in this group had significant test results or could actually be diagnosed with another disease than FND, that would be an important finding.

Also, to be fair I haven't read the paper and have no idea how the 'diverse autonomic disturbances' were identified and whether the found antibodies (and their positive or negative correlation with some of the diverse autonomic symptoms) could actually point to something meaningful.

From the abstract, it isn't clear to me whether the presence of the found antibodies lead to an actual diagnosis of Autoimmune autonomic ganglionopathy in any of the patients -- also have to admit I never heard of this disease and only saw the Wikipedia article indicating that it "needs additional citations for verification".

It's just the way these results are hyped in the tweet without giving further details that I don't find helpful.


I share the hope though that the actual findings might eventually be helpful.


Apologies for repeated edits -- also edited my original post to add the authors' conclusion in their paper that I think justifies both cautiousness with interpreting the findings and hope that these could prove meaningful.

 

As I edited my original post, I thought I'll add the section about how they measured/ assessed the antibodies compared to the control sample:

From the paper:

"Serum antibodies against gAChR α3 and β4 subunits were quantified using a LIPS assay (13, 19), in which specific antibodies are bound to a Gaussia luciferase-tagged antigen and the bound antibody is quantified by measuring luciferase activity with a luminometer.

"The results are expressed as relative luminescence units (RLU).

"Serum was considered positive for anti-gAChR α3 or β4 antibodies if the RLU of the test sample exceeded a cut-off value of three standard deviations (SDs) greater than the mean RLU of the control sample (sera obtained from healthy individuals). We evaluated the antibody levels as an antibody index (A.I.). A.I.= [measurement value of the sample serum (RLU)]/[the cut-off value (RLU)].

 

I think investigating these 9 patients' illness / diagnosis trajectory, including reviewing the diagnosing clinicians' thoughts and decisions would be worth a paper too...