For years, experts in functional neurological disorder (FND) have cited a seminal study in their field to claim that the diagnosis was the second-most-common presentation at outpatient neurology clinics, with a prevalence of 16%. This claim was, and is, categorically untrue. The Scottish Neurological Symptoms Study (SNSS), which yielded multiple papers about a dozen years ago, actually found that 209 out of 3781, or 5.5%, were identified as having conversion symptoms. (Conversion disorder is the old name for FND.) At that rate, it was the eighth-most-common presentation in the SNSS, not #2.
This discrepancy was pointed out to me a year or so ago by a valued source. I blogged and posted on social media about the issue. I also wrote—twice–to a major journal seeking a correction in one such paper. I received no response. Two weeks ago, I sent
a letter seeking a correction to another major journal,
NeuroImage: Clinical. Several colleagues—from Berkeley, Columbia, Johns Hopkins, University College London, etc—co-signed the letter.
The authors have now agreed to correct the false statement that the SNSS found FND to be the second-most-common presentation. The correction is inadequate in some respects. Nevertheless, I hope it means that they will at least no longer cite the SNSS to claim FND is the #2 presentation at outpatient neurology clinics, with a prevalence of 16%. I also hope the FND experts themselves will now initiate corrections in the dozens of papers that have included these untrue data points. It will be a tedious process for all involved if our group has to send out letters to journal editors about every single one of these papers.
