What you need to know about FND

What is functional neurological disorder (FND)?

FND is often described as a glitch in the brain's ‘software’ rather than an issue with its ‘hardware’. In other words, the challenge lies in how the brain and nervous system are functioning, rather than in any structural damage.

This is why, if you’re referred for a magnetic resonance imaging (MRI) scan due to your symptoms, the results may not show any obvious physical changes. However, that doesn’t mean the symptoms aren’t genuine.

The symptoms of FND can include:

• Motor symptoms - limb weakness, functional tremor, twisting muscle contraction (dystonia), gait disorder, facial spasm, tics, jerks or twitches, and sudden collapses without warning (drop attacks).

• Sensory symptoms - numbness, tingling, altered limb sensation, and functional visual changes, such as blurred/double vision, light sensitivity, and reduced vision.

• Seizures and dizziness - functional seizures and persistent dizziness worsened by walking or crowds (PPPD).

• Cognitive and speech symptoms - memory or concentration issues, slurred or stuttered speech, trouble finding words, and swallowing issues.

• Dissociazione - feeling disconnected from your body or surroundings, spaced out, floating, or having out-of-body sensations.

• Altri sintomi - chronic pain, fatigue, sleep issues, migraines/facial pain, digestive issues, anxiety, depression, post traumatic stress disorder (PTSD), difficulty emptying your bladder (chronic urinary retention), and dysfunctional breathing.

Natalie Mackenzie, a brain injury expert and cognitive rehabilitation therapist from London, UK, says that the symptoms of FND are real, neurological, and can be very disabling.

She explains: “They arise from altered patterns of brain functioning rather than a lesion, degeneration or inflammation in the way we’d see in conditions such as stroke, sclerosi multipla (MS) or malattia di Parkinson.

“What seems to go wrong is the brain's ability to integrate movement, sensation, attention, emotion, and expectation in a smooth, automatic way.”

Mackenzie notes that symptoms can appear when the brain systems that control movement, attention, or our sense of agency aren’t functioning as they typically do. These aren’t things people are doing on purpose or imagining - their brain is genuinely creating the symptom, just in a functional way rather than because of structural damage.

“Research now identifies FND as a multi-network brain disorder,” she says. “It is one of the most common conditions seen in neurology outpatients, and one of the least talked about.”

FND can’t be detected on a scan, even though the brain’s signal processing is still not working correctly. As a result, FND is often misunderstood, and diagnosing it usually isn’t as simple as running a single test.

Mackenzie explains that, for a long time, medicine was much better at spotting damage than understanding dysfunction. For people with FND, this often meant years of being wrongly dismissed, disbelieved, or told it was “all in their head”.

“What we now understand is that your brain is constantly making predictions about what your body is doing and what it's about to do,” she says. “In FND, something disrupts that process. The brain becomes locked into a faulty prediction - that a leg cannot bear weight, for instance, or that a seizure is imminent.

“It can't correct itself, even when the body is sending back the right information. It's a bit like a sat-nav that keeps recalculating to the wrong route no matter what the road signs say.”

These patterns are not a choice, nor are they simply anxiety playing tricks. They are real neurological processes, and science now clearly supports this.

For a long time, FND was only diagnosed after ruling out everything else. That approach was slow and frustrating, often leaving people stuck for years, going through tests that weren’t going to give them any real answers.

Mackenzie describes how, in more recent years, there has been a shift in how FND is diagnosed.

“FND is not diagnosed because 'nothing else was found’,” Mackenzie says. “It is diagnosed because there are specific, recognisable patterns that tell a neurologist this is what's happening.”

This is incredibly important for people with FND, as an earlier diagnosis can significantly improve their chances of better outcomes.

“FND has spent over a century being bounced between neurology and psychiatry, labelled as hysteria, conversion disorder, or worse,” Mackenzie explains. “That history has slowed down research, but we are now in a much better place. Undoing that stigma takes time, and many people still encounter outdated attitudes in healthcare settings.”

Although the exact cause of FND is unknown, experts believe it often begins after a trigger, such as a physical injury, surgery, serious illness, or a stressful or traumatic event. Sometimes, it could develop after you’ve experienced intense or ongoing stress.

Mackenzie says this might even be something that seems relatively minor at the time.

“The trigger isn't the whole story, but it can be the moment the nervous system shifts into an abnormal pattern it then struggles to get out of,” she explains. “It is important to say that having a psychological trigger does not mean FND is a psychological condition. Your brain and body are not separate systems.

“Physical and emotional events both affect how the nervous system functions, and for people with FND, a combination of factors - biological, psychological, and social - usually builds the picture. Many people with FND have no identifiable psychological trigger at all.”

She adds that there isn’t a single gene responsible for FND. Research into genetic and biological vulnerability is ongoing. Some people are more susceptible than others, and prior illness, stress, or certain neurological conditions can increase that vulnerability.

A crucial first step in treating FND is getting an accurate diagnosis - and just as importantly, how that diagnosis is communicated to the person affected.

Mackenzie explains that being given the diagnosis clearly, compassionately, and with enough detail to make sense of it can be therapeutic in itself.

“For many people, understanding that their symptoms are real, that there is a name for what is happening, and that it is treatable, brings a sense of relief that begins the recovery process,” she says. “From there, treatment is usually a team effort.”

Specialist physiotherapy

One of the most common and effective treatments for FND - particularly for functional movement symptoms - is specialist physiotherapy.

Mackenzie explains that this approach differs from standard physiotherapy. Rather than focusing on strengthening a weak muscle, it recognises that the problem doesn’t lie in the muscle itself.

“The goal is to help the brain find its way back to automatic, natural movement,” she says. “This is done by shifting attention, rebuilding confidence, and gently retraining the patterns that have gone wrong.”

Mackenzie adds that research has shown this approach can be highly effective. One major trial found that people receiving specialist physiotherapy were nearly five times more likely to improve compared to those receiving standard care.

Terapia della parola

Talking therapies - particularly cognitive behavioural therapy (CBT) - are commonly used in the treatment of FND.

“This can help with understanding triggers, breaking the cycles that keep symptoms going, and managing the fear and avoidance that often builds up around symptoms,” says Mackenzie.

“For functional seizures in particular, CBT has a strong evidence base. A large UK trial found it meaningfully reduced seizure frequency and improved quality of life.”

Terapia occupazionale

Occupational therapy can play an important role in managing the practical challenges of living with FND.

Mackenzie explains that this can include managing energy levels, adapting daily routines, and supporting independence. Some people may also benefit from medicine to help manage pain, improve sleep, or support their mood.

“Recovery looks different for everyone,” Mackenzie says. “Some people improve significantly and relatively quickly. Others have a longer road. FND can be persistent, and not everyone reaches full recovery. But improvement is genuinely possible at any stage, and the research is clear that people who feel in control of their own recovery tend to do better.

Neuroplasticity is the brain’s ability to adapt and reshape itself through experience. It’s how we learn new skills, recover from injury, and form habits over time.

Mackenzie explains that, in FND, neuroplasticity plays a role in both how symptoms develop and how they can improve.

“When your brain repeatedly produces a symptom - such as a tremor, weakness, or a seizure pattern - those pathways can become more established over time,” she says. “Your brain gets better at doing what it’s been doing, even when what it’s been doing is causing harm.

“That’s not the person’s fault. It’s simply how the brain works. The same process can work in reverse - the brain can learn new, healthier patterns too. That’s the foundation of rehabilitation in FND.”

Mackenzie adds that, with the right support, your nervous system can be guided towards new ways of moving, responding, and interpreting signals from your body.

“Recovery is possible, not always quick or complete, but genuinely possible,” she says. “Understanding neuroplasticity is part of why we can say that with confidence.”