By David Tuller, DrPH
This morning I sent the following letter to CNS Spectrums, a neuroscience journal published by Cambridge University Press. Subject line: “Correction needed for etiological statement in ‘Functional neurological symptoms occur commonly in healthy adults: implications for the pathophysiology of FND.'” Depending on the response, or lack of one, I might also formally submit the letter for publication.
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Dear Editor—
In the introduction of a recent paper in CNS Spectrums, “Functional neurological symptoms occur commonly in healthy adults: implications for the pathophysiology of FND,” the authors write that “functional symptoms are neurological symptoms which are generated by abnormal brain processing.” (FND refers to “functional neurological disorder.”)
However, this description represents the authors’ theory about what is causing such symptoms. It is not a proven fact, and should not be disseminated as if it were. In reality, the authors do not know what causes functional neurological symptoms or FND and are offering their best guess. But the statement conveys a level of certainty that cannot be justified based on the existing state of evidence.
It would be different if the authors provided data to support this categorical claim, but they do not. Nor does the article cited by the authors—a 2022 paper in Lancet Neurology, “Functional Neurological Disorder: New Phenotypes, Common Mechanisms.” That paper, at least, framed the issue in a more cautious and appropriate manner by referring to the “current understanding” of the factors that many investigators believe are causing these complex conditions.
It is harmful to the scientific process when authors present their theories as documented and indisputable facts. The definitive assertion about the cause of functional neurological symptoms should therefore be corrected. (I have cc’d the corresponding author and the editors-in-chief.)
Thank you for your consideration of this matter.
Best–David
David Tuller, DrPH
Senior Fellow in Public Health and Journalism
Center for Global Public Health
School of Public Health
University of California, Berkeley