Is Conversion Disorder the same as Functional Neurological Disorder?

14 Mar 2026 FndNope Moderator

2

It is commonly understood that FND historically evolved from Conversion Disorder (CD), which in turn emerged from Hysteria. Functional Neurological Disorder, Reframed

But is “evolved” really the right term? Isn’t FND simply a more user-friendly name for CD and, by definition, still essentially Hysteria? From the perspective of FND advocates, FND is not considered to have evolved from CD; rather, they claim it has completely replaced it (some even suggest that conversion theory was debunked).

Consider the following excerpt from the FND Hope FAQ section, which asks: "Is Conversion Disorder the same as Functional Neurological Disorder?"

 Yes and No

Yes, both are listed as the same illness in the APA diagnostic manual known as the DSM-5 and both are typically used interchangeably with one another.

No, Conversion Disorder [CD] and Functional Neurological Disorder [FND] are theoretically different concepts. CD is the theory that symptoms are the result of suppressed psychological trauma converting to physical symptoms. Studies have found many do not have a history of major emotional traumatic events, or major depression/anxiety. Even if a patient does have mental health issues, now or in their past, there is no quantifiable way to confirm a correlation to symptoms. The change in criterion now makes it easier for physicians to use the CD/FND diagnosis, where in the past they couldn’t when they found their patient did not meet the criterion standard and there was no “converting” of symptoms taking place. Because there is sometimes no identifiable mental health issues, the need to identify one was removed. However, there are some patients who do identify with the Conversion Disorder theory.

We advocate that patients receive respectable and equal care based on their needs.

While this text loosely paraphrases the DSM-5, it is somewhat misleading. Saying FND and CD are “theoretically different concepts” overstates the distinction, making them sound like entirely separate disorders, which they are not.

FND is an updated diagnostic framework of CD, which incorporates ideas from conversion theory as one of several diagnostic frameworks. Conversion theory is no longer required for diagnosis, but it is still studied and applied in some cases. What Does Neuroscience Tell Us About the Conversion Model of Functional Neurological Disorders? Stressful life events and maltreatment in conversion (functional neurological) disorder: systematic review and meta-analysis of case-control studies

This is essentially like saying all Scottish citizens (CD) are British citizens but not all British citizens (FND) are Scottish. Every case diagnosed as Conversion Disorder (CD) fully qualifies as Functional Neurological Disorder (FND) since CD is included within the same DSM-5 category. Yet FND is the broader more inclusive umbrella that covers cases where the classic conversion theory (suppressed trauma turning into symptoms) is not required evident or even applicable without needing to separate them into entirely different disorders.

This distinction is important because misrepresenting FND as a completely new disorder can confuse patients about their medical history, mislead research and clinical understanding, and undermine credibility in debates or advocacy.

Ultimately, the renaming of Conversion Disorder to FND was intended to reduce stigma and modernise the terminology. However, from a sceptical perspective, it may have had the opposite effect. By presenting FND as a completely new disorder, the change can obscure historical context, create confusion about its true hypothetical nature Analyzing the process of diagnosing FND reveals a necessary element of presumption, which I propose underlies some of the uncertainty, discomfort, and stigma associated with this diagnosis. , and give the impression of scientific progress where little has actually occurred, potentially increasing scepticism and even reinforcing stigma.