FND is often described as a defect in the ‘software’ of the brain rather than a ‘hardware’ problem. In other words, the challenge lies in how the brain and nervous system are functioning, not in any structural damage.
This is why, if you are sent for a magnetic resonance imaging (MRI) scan because of your symptoms, the results may not show any obvious physical changes. However, this does not mean that the symptoms are not real.
Symptoms of FND may include:
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motor symptoms – Weakness of the limbs, functional tremors, muscle contractions (dystonia), gait disorders, facial twitches, tics, tremors or twitches, and falling suddenly without warning (drop attack).
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sensory symptoms – Numbness, tingling, altered limb sensation, and functional visual changes, such as blurred/double vision, light sensitivity, and reduced vision.
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seizures and dizziness – Functional seizures and persistent dizziness that are worsened by walking or crowding (PPPD).
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cognitive and speech symptoms – Memory or concentration problems, slurred or slurred speech, trouble finding words, and trouble swallowing.
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separation – Feeling detached from your body or surroundings, drifting off, floating, or experiencing out-of-body sensations.
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other symptoms – Chronic pain, fatigue, sleep problems, migraine/facial pain, digestive problems, anxiety, depression, post traumatic stress disorder (PTSD), difficulty emptying the bladder (chronic urinary retention), and dysfunctional breathing.
Natalie McKenzie, a brain injury specialist and cognitive rehabilitation therapist from London, UK, says the symptoms of FND are real, neurological, and can be very disabling.
She explains: “They arise from altered patterns of brain functioning rather than from a lesion, pathology or inflammation, as we see in conditions such as stroke, multiple sclerosis (MS) or Parkinson’s disease.
“What seems to be going wrong is the brain’s ability to integrate movement, sensation, attention, emotion and expectation in an intuitive, automatic way.”
McKenzie says symptoms can appear when the brain systems that control movement, attention, or our sense of agency aren’t working as well as they normally do. These are not things that people are doing consciously or imagining – their brain is actually causing symptoms in a functional way rather than through 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 discussed.”
FND may not be detected on a scan, even if the brain’s signal processing is still not working correctly. As a result, FND is often misunderstood, and diagnosing it is usually not as easy as running a test.
McKenzie explains that, for a long time, medicine was much better at detecting damage than understanding the disease. For people with FND, this often means years of being unfairly dismissed, disbelieved, or told it was all in their mind.
“What we understand now is that your brain is constantly predicting what your body is doing and what it’s going to do,” she says. “In FND, something disrupts that process. The brain locks into a faulty prediction – for example, that a leg can’t bear weight, or that a stroke is imminent.
“It can’t correct itself, even if the body is sending back the right information. It’s a bit like a sat-nav that keeps recalculating on the wrong route, no matter what the road signs say.”
These patterns are not a choice, nor are they merely anxiety-inducing tactics. They are real neurological processes, and science now clearly supports this.
Fluctuations of FND Symptoms
The symptoms of FND often fluctuate dramatically throughout the day, causing others – and sometimes even the person experiencing them – to doubt their reality.
McKenzie explains that this is because FND is not caused by fixed structural damage. Symptoms are sensitive to things like fatigue, stress, where your attention is focused, and how safe or overwhelmed your nervous system feels.
“When you’re tired or anxious, symptoms often worsen,” she says. “They may be spontaneous when you’re distracted or absorbed in something else. That variability is a feature of FND, not evidence against it.”
For a long time, FND was diagnosed only after everything else had been ruled out. That approach was slow and frustrating, often leaving people stuck for years, going through tests that gave them no real answers.
McKenzie explains how, in recent years, there has been a change in how FND is diagnosed.
“FND isn’t diagnosed because ‘nothing else was found,'” says McKenzie. “It’s diagnosed because there are specific, recognizable patterns that tell a neurologist that’s what’s happening.”
This is incredibly important for people with FND, as earlier diagnosis can significantly improve their chances of a better outcome.
McKenzie explains, “FND has spent more than a century oscillating between neurology and psychiatry, labeled as hysteria, conversion disorder, or worse.” “That history has slowed research, but we are in a much better place now. It took time to erase that stigma, and many people still face outdated attitudes in health care settings.”
Differentiating FND from other health conditions
Sometimes FND can be mistaken for, or suspected to be, other conditions that appear similar due to overlapping symptoms. Examples include multiple sclerosis (MS), Parkinson’s disease, Tourette syndrome, and epilepsy. This often means that people may have to undergo extensive testing for other conditions, which can be physically and emotionally draining.
McKenzie highlights that the average time it takes to receive a correct FND diagnosis is seven to ten years.
“That’s a long time to be unhealthy without answers,” she says. “Often those years are spent being told you have something you don’t have — or nothing at all.
“The good news is that neurologists can now identify FND through specific signs on examination, meaning people no longer have to wait until everything else has been ruled out.”
An example of this is functional weakness – a neurologist may notice that a limb that seems too weak to move in one position functions normally in another position. In functional tremor, the tremor may shift or even stop when the person’s attention goes elsewhere.
“These patterns are recognizable and consistent,” says McKenzie. “They point towards the FND instead of away from everything else.”
She notes that functional seizures are one of the most common presentations of FND and are often confused with epilepsy.
“It’s worth knowing that some people have both functional seizures and epilepsy at the same time,” she says. “This is why thorough evaluation always matters.
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 may develop after you experience intense or sustained stress.
McKenzie says it may even be something that seems relatively minor at the time.
“The trigger is not the whole story, but it may be the moment when the nervous system shifts into an abnormal pattern and then struggles to get out of it,” she explains. “It’s important to say that having psychological triggers does not mean that FND is a psychological condition. Your brain and body are not separate systems.
“Both physical and emotional events affect the functioning of the nervous system, and for people with FND, a combination of factors – biological, psychological and social – usually make up the picture. Many people with FND have no identifiable psychological trigger.”
She further says that there is no single gene responsible for FND. Research on genetic and biological vulnerabilities continues. Some people are more sensitive than others, and prior illness, stress, or certain neurological conditions can increase that vulnerability.
An important first step in the treatment of FND is to receive an accurate diagnosis – and equally important is how the affected person is informed of that diagnosis.
McKenzie explains that giving the diagnosis clearly, compassionately, and with enough detail to understand it can be therapeutic in itself.
She says, “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.” “From there, treatment is usually a team effort.”
specialist physiotherapy
One of the most common and effective treatments for FND – especially for functional movement symptoms – is specialist physiotherapy.
McKenzie explains that this approach differs from standard physiotherapy. Instead of focusing on strengthening weak muscles, it recognizes that the problem is not with the muscles themselves.
“The goal is to help the brain get back to automatic, natural motion,” she says. “This is done by shifting focus, rebuilding confidence, and gently retraining patterns that have gone wrong.”
McKenzie says research has shown this approach can be highly effective. A major trial found that people who received specialist physiotherapy were almost five times more likely to improve than those who received standard care.
talking therapy
Talking therapy – especially cognitive behavioral therapy (CBT) – is commonly used in the treatment of FND.
“This can help to understand triggers, break the cycle that maintains symptoms, and manage the fear and avoidance that often arise around symptoms,” says McKenzie.
“Particularly for functional seizures, CBT has a strong evidence base. A large UK trial found that it meaningfully reduced the frequency of seizures and improved quality of life.”
occupational therapy
Occupational therapy can play an important role in managing the practical challenges of living with FND.
McKenzie explains that this can include managing energy levels, adopting a daily routine, and supporting independence. Some people may also benefit from medication to manage pain, improve sleep, or improve their mood.
“Recovery looks different for everyone,” says McKenzie. “Some people improve significantly and relatively quickly. Others have a longer road. FND can be persistent, and not everyone makes a full recovery. But recovery at any level is indeed possible, and research is clear that people who feel in control of their own recovery do better.
Neuroplasticity is the brain’s ability to adapt and reshape itself through experience. This is how we learn new skills, recover from injuries, and form habits over time.
McKenzie 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 pattern of tremors, weakness, or seizures — those pathways can become more established over time,” she says. “Your brain gets better at doing what it’s supposed to do, even when what it’s doing is causing harm.
“It’s not the person’s fault. It’s just how the brain works. The same process can work in the opposite way too – the brain can also learn new, healthy patterns. This is the foundation of rehabilitation in FND.”
McKenzie says that, with the right support, your nervous system can be directed toward new ways of transmitting, responding to, and interpreting signals from your body.
“Recovery is possible, not always quickly or completely, but really possible,” she says. “Understanding neuroplasticity is part of why we can say this with confidence.”
Reliable source for FND support
If you want to learn more about FND, including the support available and what to do around diagnosis and treatment, McKenzie recommends the following resources:
