For Functional Neurological Disorders (FND), David Perez, MD, MMSc, director of the Functional Neurological Disorder Clinical Unit and Research Program at Massachusetts General Hospital says, it’s important to investigate potential risk factors and triggers that can also perpetuate the disorder. Yet, for each patient, these elements might be unique and interact differently.
Adverse early life experiences, such as abuse or neglect, can be a risk factor for FND. So can a history of depression, anxiety, and trauma symptoms. But these are far from universal among FND patients, and an assumption of their centrality to the condition has contributed over the years to neglected and misunderstood patients.
“Some FND patients do not report adverse life experiences and have never been in therapy,” Perez says. “They’re used to pushing through and doing 120 percent. For reasons that might be personal to each case, that person with high-achieving tendencies can also develop FND.”
Using a brain-as-computer analogy, Perez notes that there are many ways that software can crash. “That’s why a one-size-fits-all formulation falls flat in the FND population.”
FND tends to be triggered by something that draws attention to the body. That might be a common event, such as a minor physical injury, a viral illness, or even a vaccination. “The physical triggering event is usually something that would be expected to get better,” explains St. George’s, University of London, neurologist Mark Edwards, PhD, on the website FND Hope.
“Some FND patients do not report adverse life experiences and have never been in therapy,” Perez says. “They’re used to pushing through and doing 120 percent. For reasons that might be personal to each case, that person with high-achieving tendencies can also develop FND.”
“For example, a flu that would be expected to go [away] after a few days’ rest, but instead symptoms continue and functional symptoms emerge. Sometimes this process can be very quick and dramatic or sometimes much slower.”
It’s not the injury, illness, or event itself that triggers FND, but the attention, awareness, emotion, and meaning-making that accompanies it. If someone has an injury to their leg, they might then fixate on it, says London-based psychiatrist Alastair Santhouse, MA, FRCP, FRCPsych, author of Head First: How the Mind Heals the Body. “They notice the sensations in that part of the body, they’re hesitant to use it, and the symptom develops further. By the time you see them in the clinic, they may already be walking with a limp or using walking aids.”
Paying attention to the body is not inherently dangerous, notes Gavin Martin who was diagnosed with an FND in 2010 (learn more about his story here). But attention can amplify signals and give form to ambiguous feelings in a way that isn’t always helpful. “Imagine I’m walking through a field and feel the tickling of the grass on my legs, and I suddenly encounter a spider and it freaks me out: In the future, my brain at a subconscious level will be more likely to associate the ambiguous feeling of grass on my legs with the presence of a spider.”
In this way, FND isn’t caused by physical or psychological factors alone, but by the way they interact in the brain. “They’re both converging on a common system in the brain, where all these things are processed together. To some extent, they become indistinguishable,” he explains.
This process is not voluntary and can result in symptoms that are very real. It also helps explain why postconcussion patients or people with “organic” neurological disorders such as Parkinson’s, epilepsy, or MS are particularly vulnerable to developing functional-neurological symptoms in addition to those caused by their primary condition.
As Martin describes it, “The brain learns the injury, absorbs it, and then reenacts it.”
“We are not talking about personal flaws or weak-willed patients wishing to be sick,” Perez stresses. This understanding is crucial for providers to deliver a diagnosis of FND clearly and empathetically — and to point patients toward helpful treatments.
This was excerpted from “What Is a Functional Neurological Disorder?” which was published in the January/February 2023 issue of Experience Life.
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