When we talk about Functional Neurological Disorder (FND), the term "functional" can stir up a mix of confusion and frustration, particularly for those living with related conditions like ME/CFS and fibromyalgia. The word “functional” is often misunderstood, and it doesn’t help that some people feel it downplays the seriousness of their symptoms. So, what does “functional” actually mean, and why are conditions like ME/CFS and fibromyalgia sometimes grouped under this umbrella?
What Does "Functional" Mean?
In a medical context, “functional” refers to how the body functions rather than the structure of the body. In other words, the issue is not visible in scans or tests that look for structural damage (like broken bones or tumours). It’s a disruption in function, particularly in the nervous system, that’s at the heart of FND.
This doesn’t mean the symptoms aren’t real. In fact, FND symptoms can be just as debilitating as those from structural conditions, affecting movement, speech, or cognition. However, because they don’t show up on standard medical tests, the word “functional” often gets misinterpreted as “all in the head,” which is not the case.
The Science Behind Functional Disorders
In FND, the problem lies in how the brain sends and receives signals. Think of the brain as a computer where the hardware is fine, but the software is glitching. The brain misinterprets signals, which leads to physical symptoms like tremors, paralysis, seizures, and more. This dysfunction often correlates with abnormalities in the brain's circuits that regulate movement, sensation, and cognition.
Interestingly, ME/CFS and fibromyalgia also involve dysfunction in the brain and nervous system, particularly in how the brain handles stress, pain, and fatigue. This is why some experts suggest they may also be considered functional disorders, even though they manifest differently.
Why Do People Get Annoyed by the Term “Functional”?
For those living with these disorders, the term "functional" can feel dismissive. It’s often interpreted as implying the symptoms are “less real” because they don’t have a clear-cut, structural cause. Many people with ME/CFS, fibromyalgia, or FND have spent years trying to get a diagnosis and may feel frustrated by being lumped under a term that seems to minimize their experience. The stigma surrounding mental health also plays a role, as “functional” is sometimes wrongly equated with being “psychological.”
Are Other Disorders Functional?
This is a tricky question. While FND, ME/CFS, and fibromyalgia share some common ground—namely nervous system dysfunction—they are distinct in how they affect individuals. The term "functional" can technically apply to any disorder where nervous system miscommunication is central, but this doesn’t mean they all fit neatly into the same category.
However, all these conditions involve an overactive or hypersensitive nervous system, which is why they sometimes fall under the “functional” umbrella.
Functional and Nervous System Disorders: A Connection
What these conditions have in common is that they are disorders of regulation. The nervous system, especially the autonomic nervous system (which controls functions like heart rate, digestion, and stress responses), plays a huge role in both FND and related disorders like ME/CFS and fibromyalgia. In all cases, the nervous system is out of balance, often in a state of hyper-arousal or hyper-sensitivity.
Research suggests that in FND, parts of the brain responsible for controlling movements and processing emotions don’t communicate properly. Similarly, in ME/CFS and fibromyalgia, there’s often a misfire in how the brain and body interpret signals of pain, fatigue, and other stressors.
These disorders are far from "just psychological"—they represent a breakdown in how the brain and body work together, underscoring the complexity of “functional” disorders.
Why Understanding "Functional" Matters
Understanding what “functional” truly means can be empowering. It shifts the focus from “Is this real?” to “How is this happening?”. It acknowledges that while the brain and nervous system might be at the root, the symptoms are very much real and require a comprehensive, multi-faceted approach to treatment, often involving neurological rehabilitation, brain retraining, and lifestyle adjustments.
In conclusion, while the term "functional" can be frustrating, it accurately highlights that conditions like FND, ME/CFS, and fibromyalgia stem from miscommunication within the nervous system. These disorders aren't just about what standard tests can reveal—they affect the way the brain and body function, leading to debilitating symptoms from head to toe, including pain, fatigue, and cognitive issues.
Those who downplay the severity of functional disorders often fail to grasp the complexity of the nervous system and the far-reaching impact these conditions have on the body. It’s not just a misunderstanding—it's a fundamental lack of knowledge about how the body truly works.
Whether it’s FND, ME/CFS, or fibromyalgia, the key is in understanding and treating how the brain and body function, rather than focusing only on what standard tests can reveal.
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