Review Systematic review of movement disorders mislabeled as functional: when incongruence misleads 2026 Marín-Medina et al

[cstruter]

There is no use for theoretical models that are not grounded in reality.

Predictive processing makes no sense for symptoms because there is no need for high accuracy.

It make sense for coordination because the nerve signals from hands are too slow to achieve high enough accuracy to interact with fast objects and movements in 3D space. So we can fool it.

Search for «noakes» on the forum, restricted to posts by the user Snow Leopard to find most of the discussions and studies falsifying the hypothesis of predictive processing causing symptoms.

I am personally sceptical of predictive processing as well as a complete or primary explanation for these conditions. However, for the sake of discussion with those who do find the model useful, let's assume it can plausibly account for the positive functional signs clinicians rely on, such as Hoover’s sign, entrainment, and distractibility.

Even under that assumption, why does a predictive processing explanation automatically translate into an FND/FMD diagnosis, rather than simply a predictive processing issue that may be secondary to prior organic injury or damage? If the model effectively treats any resulting "scar" in the predictive system as the diagnosis itself, we will almost certainly miss investigating and addressing the underlying organic causes.

If real prior injury can leave lasting changes, something like programmatic scar tissue in the brain's generative model, that produce exactly the same variable or incongruent movements, then those signs no longer clearly rule in a functional or psychogenic disorder. They could instead reflect downstream effects of genuine pathology.

The Marín-Medina review already highlights how easily incongruence, and even single inconsistency signs, can mislead clinicians into mislabeling organic movement disorders. So I am genuinely curious: what justifies treating PP signs as synonymous with FND/FMD instead of as a possible consequence of prior real damage? I am not claiming this is definitively the case, just questioning the automatic leap.

 

[Jonathan Edwards]

So I am genuinely curious: what justifies treating PP signs as synonymous with FND/FMD instead of as a possible consequence of prior real damage? I am not claiming this is definitively the case, just questioning the automatic leap.

I think most of us on the forum would agree with that question. To my mind things like Hoover's sign simply indicate that the problem is at a higher level of processing than can be analysed by the traditional neurological examination. It also begs the question of what is meant by FND. The FND pundits appear to use the term both to mean a non-structural pathology and a neo-Freudian version of 'hysterical conversion', suitable for psychodynamic therapy.

 

[cstruter]

The criteria for FND is pretty loose, what is officially stated vs what clinicians actually do is vastly different, so you tred in the realm of biblical hermeneutics, so really depends which church of FND you are talking to

 

[Jonathan Edwards]

The criteria for FND is pretty loose, what is officially stated vs what clinicians actually do is vastly different, so you tred in the realm of biblical hermeneutics, so really depends which church of FND you are talking to

Right. I think that was what I was saying.

 

[Peter T]

The biggest cop out by advocates for FND is by those that justify the concept in that it provides a narrative that patient can feel comfortable with.

 

[cstruter]

The biggest cop out by advocates for FND is by those that justify the concept in that it provides a narrative that patient can feel comfortable with.

I am personally VERY uncomfortable with everything I am seeing, even when applying their own narrative, I cannot see any reason to slap labels like this onto anything

 

[rvallee]

The biggest cop out by advocates for FND is by those that justify the concept in that it provides a narrative that patient can feel comfortable with.

Even though, of course, most people are not. In fact most reject it outright, often directly to their own faces. Which is known, and acknowledged in the literature, so it's just a lie. But they get around that by framing it like you did, how it "may" provide such an explanation, how a fraction do accept them, and to them that's the same as 100% success, because failure is what's expected, so they don't even need to show any results. They are essentially cashing checks for goods they never deliver on the promise that they will figure it out one day, but it's as good as sold for now because, uh, reasons.

Mostly because they still have nothing to show for it after over a century of over-promising and never-delivering and there is no mechanism or institution within the industry with enough courage to end this nightmare ideology. Even though there is zero possibility of anyone ever being properly punished for it, because every institution is as guilty as them, of letting it happen.

With time there will be acknowledgement that those "signs" aren't actually meaningful, but that it doesn't change the validity of the model because blah, blah, or possibly bulah. Possibly they'll come up with another "sign" that will end up disproved, maybe they'll mix things up a bit. Then they might invent another false assertion, or maybe not bother for a while, probably spend a few years asserting how the clinical trials prove it, then when that gets old, and the latest trials are identical to the first ones anyway, they'll get back to simply saying that they just know, clinically they could show it to you, in private, but they've been doing this for decades by now so it clearly can't be wrong. Rinse. Repeat.

It's easy to get away with anything when the whole system allows them to get away with everything. Psychosomatic ideology has never needed positive evidence, only negative evidence showing that it's something else. As antiscientific as it gets. And they call this evidence-based medicine.

 

[Utsikt]

@cstruter I have no idea how to defend the concept of FND in any of the ways it’s usually defined in the literature.

 

[Immunert]

The abstract of this one is just empty drivel. It has no scientific content.

You should probably read the full paper then? I don’t agree that it is empty drivel or has no scientific content. I find it quite interesting. I’m not sure why you think it’s nonsense.

 

[Immunert]

I am afraid that these days a 'top most accepted theory' is just what is in fashion in the buzzword circuit. I have been personally involved in brain research for twenty five years. We have known that the brain predicts since Willaim James's time in 1890. It is nothing new. The term predictive coding came up maybe forty years ago. It is part of the story but only a part.

What makes you say my statement is not true? I have read Mark Edwards's stuff and he makes this mistake. We have discussed it here and others agree. And yes, if predictive coding is part of the normal brain machinery then it will not explain the abnormal without some explanation of what is different in the abnormal.

There are vast numbers of papers claiming predictive coding is involved because this is what is currently trendy. I have not so far found any that make sense. I am not going to trawl through lists of URLs but if you can point out exactly why I am wrong then please do.

I don’t see it as trendy. Like you said, it’s been an active area of neuroscience research for decades. Usually trendy things in medicine are new discoveries where the applications and claims go way beyond what the evidence shows. That’s clearly not the case here.

I provided you with several papers that I believe show why you are wrong in some of your statements. I’m no expert though. It’s fine if you don’t want to read through them, but then I’m not sure why you’d have an opinion on any of this without being adequately informed.

 

[Jonathan Edwards]

I provided you with several papers that I believe show why you are wrong in some of your statements. I’m no expert though. It’s fine if you don’t want to read through them, but then I’m not sure why you’d have an opinion on any of this without being adequately informed.

I forget the detail now but I did read more and it seems that the modellers actually agree with me that 'predictive coding' is the opposite of what is needed, as we identified here on the forum years back.

Neuroscientists who dabble in psychology like to think they are doing real science but there are hardly ever any valid tests of the theories and since we have no way of building up predictions from actual neural signals since we do not understand how the system works at that level this is not very surprising.

For the last ten years i was Book Reviews Editor for Journal of Consciousness Studies and read all the books on this topic before sending them out to reviewers. I was a regular attendee at working groups involving neuroscientists from Queen Square and philosophers at the Institute of Philosophy. I am very satisfied that i am 'adequately informed'!!