Trial By Error: Psych Medicine’s Rejects Request for Correction of Prevalence Rates Cited in FND Paper–Updated

By David Tuller, DrPH

UPDATE: Not long after I sent the letter repeating our request for a correction, I received a response directly from Professor Murray, the editor-in-chief of Psychological Medicine who had commented on the length of our initial request for a correction. Here it is:

From: Robin Murray 
Date: Thu, Jul 20, 2023 at 9:02 AM
Subject: Re: request for correction in 2021 paper on functional neurological disorder


Say. “ Dear David Tuller,
Thank you for your further letter declining our offer of publishing a letter from you and your colleagues.

We will take no further action.”



I have recently sent out a few letters to major journals seeking corrections in articles that have mis-reported the estimated prevalence of functional neurological disorder in a seminal 2010 study in their field of expertise. So far one journal, NeuroImage: Clinical, has agreed. Others seem more reluctant. I received the following non-responsive response from Psychological Medicine, the journal that published the arguably fraudulent PACE “recovery” paper in 2013. This august publication continues its record of refusing to acknowledge self-evident errors. I have responded on behalf of the group of us seeking these necessary corrections.

Response from someone at Psychological Medicine–

Dear David

The Editor in Chief says:

“Thank you for your recent long letter concerning functional neurological disorder.  My understanding is that this letter reflects a general statement of your views rather than a specific criticism of the article published in Psychological Medicine by Diez et al (2021). The correspondence columns in our journal are concerned particularly with articles previously published in our journal.  However, your letter is more concerned with articles published in other journals by Stone and his colleagues.

Therefore I am afraid your letter does not qualify for publication in Psychological Medicine. However, if you would like to write a short letter commenting specifically on the article by Diez et al (2021), then we would consider it favourably. It should be no more than 500 words and 9 references including Diez et al.”

Our response


Thank you for relaying the message from the editor-in-chief. On behalf of our group, I am replying directly to you as the chosen conduit of information. Please relay the following response back to the editorial leadership. (I have cc’d both editors-in-chief, the members of our group, and the senior and corresponding author of the paper under discussion.)

While we appreciate Psychological Medicine’s favorable disposition toward publishing a 500-word letter with up to nine references as correspondence, we are nonetheless surprised. As far as we know, our letter did not indicate any such interest on our part.

The subject line of our letter was “request for correction in 2021 paper on functional neurological disorder.” That seemed explicit enough at the time. So did the last sentence of our request: “The citation in Diez et al—or rather, the self-evident mis-citation–should be corrected.”

It appears that the editor-in-chief (whichever one of the two is handling this matter) might have found the length of our letter daunting. Whatever the source of confusion, he is mistaken in his understanding that our “request for correction” was “a general statement of [our] views rather than a specific criticism of the article published in Psychological Medicine.” To reiterate our point: The specific criticism of the article in Psychological Medicine was that it had disseminated the categorically untrue claim that the most authoritative study of FND prevalence found this diagnosis to be the second-most-common at outpatient neurology clinics.

We noted that Diez et al– “Reduced limbic microstructural integrity in functional neurological disorder” –included the following sentence: “For much of the 20th century, functional neurological (conversion) disorder (FND) was marginalized across neurology and psychiatry despite being the second most common reason for neurological referral and incurring significant healthcare costs.” As we also noted, the sentence referenced “Who is referred to neurology clinics?—the diagnoses made in 3781 new patients,” a 2010 paper from Stone et al that was published in 2010 in Clinical Neurology and Neurosurgery.”

Our request for a correction explained in detail that the “second most common” claim relied on the tripling of Stone et al’s actual prevalence rate for FND, formerly called conversion disorder, from 5.5% to 16%. In fact, Stone et al found conversion disorder/FND to be the eighth-most-common diagnosis, not the second-most-common. We wrote about all this at length not in order to overwhelm the editor-in-chief but to document the irrefutable case for a correction.

In our brief, we noted that Diez et al’s senior and corresponding author, Dr Perez, recently agreed to correct the exact same misstatement based on the exact same citation in an article for which he was the lead author, published in another major journal. In that case, the editorial team of the journal, NeuroImage: Clinical, responded with impressive alacrity, offering to publish as soon as possible a corrigendum proposed by Dr Perez and his co-authors.

We also pointed out that Professor Michael Sharpe—the senior author of Stone et al and a current member of Psychological Medicine’s editorial board–is the co-author of the section about conversion disorder on UpToDate, the medical education site. This section, which was updated in June of last year, cites Stone et al as having found the prevalence of conversion disorder at outpatient neurology clinics as 6%. This data point in UpToDate is obviously inconsistent with the claim in Diez et al that the same study found FND to be the second-most-common diagnosis, which relied on the assertion that the prevalence was 16%. 

Whatever our views about FND, the facts here are straightforward. Stone et al does not support the claim that FND is the second-most-common diagnosis at outpatient neurology clinics, as should be apparent to any reader of this seminal paper. We therefore again request that Psychological Medicine and the authors of Diez et al adhere to standard principles of scientific accountability and ethics and correct the undisputed mis-citation of Stone et al.

We hope this letter helps to clarify our position.


David Tuller (corresponding author)
Center for Global Public Health
School of Public Health
University of California, Berkeley
Berkeley, CA, USA

14 thoughts on “Trial By Error: Psych Medicine’s Rejects Request for Correction of Prevalence Rates Cited in FND Paper–Updated”

  1. Should we count it as David’s first win in this mad dash to not correct the papers making the ‘second most common’ or 16% claim? How many more can he notch up, I wonder?

  2. Lady Shambles

    How bizarre! Surely medical journals are headed by intelligent people? Aren’t they? How did they manage to misunderstand that initial letter so comprehensively? One might choose to wonder if they feigned stupidity on purpose?

    On another obliquely-related topic, it’s useful to see the way in which FND proponents use ‘FND’ and ‘conversion disorder’ synonymously within their own work. Patients given this diagnosis might like to wonder why?

  3. I imagine that one of the fastest ways for an area of medicine to be brought into disrepute would be for its leading lights and its prominent journals to refuse to correct something that is patently wrong.

  4. Am I right to think that the corresponding author has also been informed (- but has not responded? If so, are they perhaps failing in their role as a corresponding author - or is it considered okay or standard practice even for them not to respond to people who raise issues about the paper?

  5. The senior and corresponding author could certainly make their voice heard at this point but apparently they have chosen not to.

  6. Mike Fraumeni

    Embarrasing, exactly. This from NORD (National Organization for Rare Disorder):
    “The exact prevalence of FND is unknown. However, research suggests FND is the second most common reason for a neurological outpatient visit after headache/migraine, accounting for one sixth of diagnoses. This means FND could be as common as multiple sclerosis or Parkinson’s disease.”

    This NORD document indicates:
    “NORD gratefully acknowledges Jon Stone MB, ChB, PhD, Consultant Neurologist, Professor of Neurology, University of Edinburgh, UK; Tim Nicholson, Honorary Consultant Neuropsychiatrist, South London & Maudsley NHS Foundation Trust and Kings College Hospital NHS Foundation Trust, London, Reader in Neuropsychiatry, Neuropsychiatry Research and Education Group, Institute of Psychiatry Psychology & Neuroscience, King’s College London; and Bridget Mildon, President/CEO FND Hope, Inc., for the preparation of this report.”

  7. Mike Fraumeni

    This case may be of interest to some, certainly to me now diagnosed with organic Paroxysmal Kinesigenic Dyskinesia with parkinsonism and on levodopa, see and I think the questions remains as functional symptoms are seen in cancer, heart disease, neurological disease etc you name it and I can find references for anyone interested, the question is “what exactly is functional neurological disorder?”:

    “Here, we present the case of a patient who was genetically diagnosed with paroxysmal kinesigenic dyskinesia (PKD). However, most of the patient’s symptoms were considered to indicate FND. To our knowledge, there are no reports of FND overlapping PKD.”!/

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