Functional Neurological Disorder, Functional Tics and Neurodiversity: Are We Missing an Important Piece of the cake?

Emerging research is identifying an interesting relationship between Functional Neurological Disorder (FND), autism and ADHD. But what does this mean for individuals experiencing functional tic-like behaviours, and could understanding someone's neurodevelopmental profile be an important part of providing effective support?

By Sarah Sharp, TicTock Therapy & Coaching Ltd

Looking Beyond the Visible Symptoms

When someone presents with Functional Neurological Disorder (FND), particularly functional tic-like behaviours, attention understandably focuses on the symptoms themselves.

The movements, vocalisations, episodes of distress and disruption to everyday life can be significant. Families often arrive at specialist services desperate to understand what is happening and how to help.

But what if, in some cases, we are not looking closely enough at the individual behind those symptoms?

What if unidentified autism, ADHD, sensory processing differences or other neurodevelopmental needs are contributing to the wider difficulties a person is experiencing?

An emerging body of research is beginning to explore the relationship between neurodevelopmental conditions and FND, with some particularly interesting findings in individuals presenting with functional tic-like behaviours.

In my own clinical practice, I have observed a striking pattern that makes this research especially relevant.

Approximately 90% of individuals I have worked with who present with functional tic-like behaviours have either diagnosed autism and/or ADHD, or characteristics that suggest possible underlying neurodevelopmental differences.

This is my own clinical estimate, rather than a formal research finding, and includes individuals without confirmed diagnoses.

Nevertheless, it is a pattern I have observed repeatedly and one that has reinforced my belief that we need to look beyond the visible symptoms.

Importantly, this is not about suggesting that autism or ADHD causes FND. Nor is it about reducing a genuine neurological condition to anxiety, stress or emotional difficulties.

It is about recognising that understanding the whole person, including their neurodevelopmental profile, may be an important part of providing appropriate, individualised support.

Understanding Functional Neurological Disorder

Functional Neurological Disorder is a genuine neurological condition involving changes in how the brain and nervous system function.

Unlike neurological conditions characterised by structural damage or degeneration, FND is generally understood as a disorder involving how neurological processes operate and interact.

FND can present in several ways, including:

• Functional movement difficulties

• Functional seizures

• Functional weakness or paralysis

• Functional sensory symptoms

• Functional speech difficulties

• Functional tic-like behaviours

Symptoms are real, involuntary and can be profoundly disabling.

FND is not simply someone imagining symptoms, deliberately producing them or seeking attention.

Modern research recognises FND as a complex condition involving interactions between neurological networks responsible for movement, attention, sensory processing, emotion and the experience of control over actions.

There is no single explanation that accounts for every individual's presentation.

Some people develop functional symptoms following physical illness or injury. Others may experience symptoms in the context of fatigue, pain, stress or other contributing factors.

For some individuals, no obvious trigger can be identified.

This is why a comprehensive, individualised assessment is so important.

And increasingly, research is suggesting that neurodevelopmental differences deserve consideration within that assessment.

What Does the Research Tell Us?

1. A 2025 Systematic Review Involving More Than 11,000 Participants

A systematic review and meta-analysis published in 2025 by Tamilson and colleagues examined the co-occurrence of autism and Functional Neurological Disorder.

The review included 24 studies involving 11,324 participants.

Researchers estimated that approximately 10% of individuals in the FND populations studied were autistic.

This is an interesting finding, particularly when considered alongside the estimated prevalence of autism in the wider population.

However, the findings varied considerably between studies, with differences in participant characteristics, diagnostic approaches and the types of functional symptoms being investigated.

The authors also identified methodological limitations and potential publication bias.

Therefore, the findings should not be interpreted as establishing that 10% of all people with FND are autistic.

Instead, they provide evidence of co-occurrence and highlight the need for further investigation into the relationship between autism and functional neurological symptoms.

2. International Research into Functional Tic-Like Behaviours

A multicentre study published in the European Journal of Neurology in 2023 examined 294 individuals with functional tic-like behaviours across 10 specialist centres.

The researchers identified several co-occurring conditions within the clinical sample.

Approximately:

• 24% had autism

• 23% had ADHD

• 66% had an anxiety disorder

• 28% had a depressive disorder

  
  

These findings are particularly relevant to clinicians working with tic disorders and functional tic-like presentations.

They demonstrate that neurodevelopmental conditions were identified in a substantial proportion of individuals receiving specialist assessment for functional tic-like behaviours.

However, the study does not establish that autism or ADHD causes functional tics.

Nor does it demonstrate that individuals with autism or ADHD are necessarily more likely to develop functional symptoms.

The research involved specialist clinical populations, meaning the findings may not reflect the wider population.

Nevertheless, it raises important questions about whether neurodevelopmental profiles should receive greater attention during assessment and treatment planning.

3. Great Ormond Street Hospital: A Particularly Interesting Finding

Research involving children and young people with functional tic-like behaviours at Great Ormond Street Hospital identified an especially striking overlap with autism.

The study examined 63 children and young people presenting with functional tic-like behaviours.

Researchers reported that 69.8% of the children in this particular clinical sample had an autism diagnosis.

Among those autistic children, approximately 61% also had ADHD.

These findings are significant because they suggest that autism and ADHD may be particularly relevant within some specialist populations of children experiencing functional tic-like behaviours.

The researchers highlighted the importance of appropriate neurodevelopmental assessment and consideration of autism-specific characteristics.

However, the findings must be interpreted carefully.

This was a relatively small study involving a specialist clinical sample. The results cannot be generalised to all children with functional tics or FND.

Nevertheless, when considered alongside other emerging research, the findings strengthen the argument for exploring neurodevelopmental differences as part of a comprehensive clinical assessment.

My Own Clinical Observations: A Pattern I Cannot Ignore

As a clinician specialising in tic disorders, Tourette syndrome and functional tic-like presentations, I have become increasingly interested in the relationship between functional symptoms and neurodevelopmental differences.

Throughout my clinical work at TicTock Therapy & Coaching, I have noticed a recurring pattern.

I estimate that approximately 90% of individuals I have worked with who present with functional tic-like behaviours have either a formal diagnosis of autism and/or ADHD, or demonstrate characteristics that raise clinical suspicion of possible underlying neurodevelopmental differences.

I want to be clear that this figure is based on my clinical observations. It has not been established through a formal research study or systematic audit, and individuals with suspected neurodevelopmental differences have not necessarily undergone diagnostic assessment.

Therefore, this figure should not be interpreted as a verified prevalence rate.

However, it is a pattern that has repeatedly stood out to me.

Some individuals arrive with established autism or ADHD diagnoses.

Others have spent years experiencing difficulties that may be consistent with an unidentified neurodevelopmental profile.

These individuals may describe longstanding experiences involving:

• Significant sensory sensitivities

• Difficulties with attention and executive functioning

• Challenges with emotional regulation

• Social communication differences

• Difficulties recognising or describing internal emotional states

• Overwhelm associated with everyday expectations

• Masking and subsequent exhaustion

• Difficulties managing changes, uncertainty or demands

  
  

What I find particularly interesting is that, in some cases, these characteristics were present long before the functional tic-like behaviours developed.

This raises an important question.

Could unidentified or unsupported neurodevelopmental needs be contributing to the wider difficulties experienced by some individuals with functional neurological symptoms?

We do not currently have sufficient evidence to establish a direct causal relationship.

However, I believe the possibility deserves serious clinical consideration.

In my experience, focusing exclusively on the functional symptoms can sometimes mean overlooking other areas in which the individual may need support.

And those other areas may be affecting their overall wellbeing, their ability to engage with treatment and their day-to-day functioning.

For me, the emerging research reinforces something I have increasingly observed in practice.

We need to understand the individual, not simply the symptoms they present with.

Why Might Autism and ADHD Be Relevant to FND?

The precise relationship between neurodevelopmental differences and FND remains unclear.

However, several overlapping areas are being explored within research, including sensory processing, interoception, emotional awareness and attentional processes.

These are not established explanations for why FND develops, but they may help us understand why exploring neurodevelopmental needs is clinically valuable.

Sensory Processing and Overload

Many autistic individuals experience sensory information differently.

Noise, lighting, clothing, touch, movement, busy environments and other sensory experiences may be particularly intense or difficult to process.

Some individuals experience heightened sensory sensitivity, while others may have reduced awareness of certain sensations.

For a person who experiences significant sensory overload, everyday environments can require considerable effort to navigate.

A classroom, workplace, supermarket or social gathering may involve demands that are difficult for others to recognise.

Over time, these experiences can contribute to exhaustion, distress and reduced capacity to manage additional demands.

Sensory processing is also relevant to research exploring how individuals with FND experience and interpret bodily sensations.

Although a direct causal link between sensory overload and functional symptoms has not been established, understanding sensory needs may be important when developing an individualised support plan.

Interoception: Recognising Internal Bodily Signals

Interoception refers to our ability to recognise and interpret signals from inside our bodies.

These include hunger, thirst, temperature, heart rate, discomfort and physiological changes associated with emotions.

Some autistic and ADHD individuals experience differences in interoceptive awareness.

For example, someone may not recognise that they are becoming overwhelmed until they reach a point of significant distress.

Another person may struggle to distinguish anxiety from excitement, hunger, tiredness or physical discomfort.

Research into FND has also explored differences in attention to bodily sensations and the interpretation of internal signals.

These overlapping areas are interesting because they suggest potential avenues for further research.

However, interoceptive differences do not establish that someone has FND, nor do they demonstrate that neurodivergence causes functional symptoms.

Alexithymia and Emotional Awareness

Alexithymia describes difficulties identifying and describing emotional experiences.

It is more commonly reported among autistic individuals, although it is not exclusive to autism.

Someone experiencing alexithymia may recognise physical sensations associated with an emotion without being able to identify or explain what they are feeling.

For example, they may notice tension, agitation, discomfort or changes in breathing without immediately recognising anxiety, frustration or excitement.

Alexithymia has also been explored within FND research.

This does not mean functional symptoms are simply unexpressed emotions manifesting physically.

FND is far more complex than that.

However, differences in emotional awareness may influence how someone recognises distress, communicates their needs or engages with particular therapeutic approaches.

Masking and Cumulative Exhaustion

Masking is another area that I believe deserves consideration.

Many autistic and ADHD individuals spend significant amounts of energy attempting to meet social expectations, manage sensory experiences or conceal their difficulties.

A child may appear settled throughout the school day while using considerable effort to manage the environment.

They may then return home exhausted, overwhelmed or unable to manage further demands.

Similarly, an adult who has spent years compensating for unidentified neurodevelopmental differences may experience substantial cumulative exhaustion.

Could this prolonged effort contribute to factors that influence functional symptoms in some individuals?

It is a plausible question, but further research is needed.

We must be careful not to suggest that masking automatically causes FND.

Nevertheless, recognising and reducing unnecessary demands may improve someone's wellbeing, regardless of whether they experience functional symptoms.

Functional Tics and Tourette Syndrome: Why the Distinction Matters

An important part of this discussion is understanding the difference between functional tic-like behaviours and neurodevelopmental tic disorders such as Tourette syndrome.

Although they can appear similar, they are not the same condition.

Tourette syndrome is a neurodevelopmental disorder characterised by motor and vocal tics, typically beginning during childhood.

Functional tic-like behaviours are a presentation of Functional Neurological Disorder.

The two conditions may differ in their typical onset, symptom patterns, clinical features and treatment approaches.

However, the distinction is not always straightforward.

Some individuals experience both Tourette syndrome and functional tic-like behaviours.

This means that someone with an established Tourette syndrome diagnosis may subsequently develop functional symptoms alongside their existing tics.

Equally, the presence of autism or ADHD does not establish whether a person's symptoms are neurodevelopmental tics or functional tic-like behaviours.

A comprehensive assessment should consider the individual's developmental history, symptom characteristics, positive diagnostic features and wider clinical presentation.

This is particularly important because the management approaches may differ.

Comprehensive Behavioural Intervention for Tics (CBIT) is an evidence-based intervention for Tourette syndrome and persistent tic disorders.

However, functional tic-like behaviours may require a different or adapted approach, depending on the individual's presentation and needs.

Where both conditions coexist, treatment planning may need to address them separately while considering the person as a whole.

Are We Missing Unidentified Neurodevelopmental Needs?

This is the question I find particularly important.

Imagine a young person presenting with significant functional tic-like behaviours.

Their symptoms may be disrupting education, social relationships, family life and everyday activities.

Understandably, the immediate focus becomes reducing the severity and impact of those symptoms.

However, a broader assessment may reveal that the individual has experienced difficulties for many years.

Perhaps they have always struggled with sensory overload.

Perhaps they find social interactions exhausting.

Perhaps they experience significant difficulties with planning, organisation, attention or emotional awareness.

Perhaps they have spent years masking their difficulties because they believed everyone else experienced the world in the same way.

And perhaps nobody has previously explored whether autism or ADHD could help explain some of these experiences.

Identifying these characteristics does not prove they caused the functional symptoms.

But it may help us understand the individual's needs.

For example, someone who experiences sensory overload may benefit from adjustments to their environment.

Someone with executive functioning difficulties may need therapeutic exercises broken down into smaller, more manageable steps.

Someone who struggles to recognise internal emotional or physical signals may benefit from support developing greater awareness of their experiences.

And someone who has spent years feeling misunderstood may benefit from a clearer understanding of their neurodevelopmental profile.

These adjustments may improve overall wellbeing and engagement with treatment.

They should not, however, be presented as guaranteed methods of reducing functional symptoms.

The Fire and the Fuel: Looking at the Bigger Picture

At TicTock Therapy & Coaching, I often use an analogy when explaining tic disorders and the importance of understanding co-occurring difficulties.

The tics are the fire. Other factors may act as the fuel.

For individuals with Tourette syndrome, factors such as anxiety, sensory overload, fatigue and unmet neurodevelopmental needs may influence the frequency, intensity or impact of their tics.

Although functional tic-like behaviours have different underlying mechanisms, I believe the broader principle of understanding contributing and maintaining factors remains relevant.

If we focus exclusively on the visible symptoms, we may overlook other difficulties that are affecting the person's quality of life.

For example, we may work on managing functional tic-like behaviours while failing to recognise that the individual is experiencing significant sensory distress throughout the day.

Or we may expect someone to complete therapeutic exercises independently without recognising that executive functioning difficulties make this particularly challenging.

We may interpret difficulties engaging with therapy as resistance, when the individual actually requires a different communication style, additional processing time or a more accessible approach.

These examples do not demonstrate that autism or ADHD causes FND.

They demonstrate why understanding someone's individual profile matters.

Sometimes, addressing the wider needs of the person is an important part of creating the conditions in which effective support can take place.

What Should Clinicians Be Considering?

The emerging research supports a broader, individualised approach to assessment.

This does not mean every individual with FND should automatically be referred for an autism or ADHD diagnosis.

It means clinicians should remain open to the possibility of previously unidentified neurodevelopmental differences, particularly when the developmental history suggests these may be relevant.

Areas worth exploring include:

Developmental history

Have difficulties with attention, communication, sensory processing or emotional regulation been present since childhood?

Sensory experiences

Does the individual experience sensory overload, sensory avoidance or significant sensitivities that affect everyday life?

Executive functioning

Are there difficulties with organisation, planning, initiating tasks, working memory or managing multiple demands?

Emotional awareness

Does the individual find it difficult to identify, understand or communicate emotional and physical experiences?

Masking and exhaustion

Does the person appear to cope in certain environments but experience significant exhaustion or distress afterwards?

Environmental demands

Are school, work, social expectations or other environments creating difficulties that could be reduced through appropriate adjustments?

Existing diagnoses and support

Has autism, ADHD or another neurodevelopmental condition previously been identified? If so, are the individual's needs being adequately accommodated?

Where clinically appropriate, further specialist assessment may be beneficial.

However, exploring neurodevelopmental characteristics does not automatically mean someone needs or wants a formal diagnosis.

Understanding their needs can still be valuable.

Does Someone Need a Formal Autism or ADHD Diagnosis?

Not necessarily.

A formal diagnosis can be extremely valuable.

It may provide a clearer understanding of longstanding experiences, support access to services and help individuals obtain appropriate adjustments in education, employment and healthcare.

For some people, receiving a diagnosis can be life-changing because it provides an explanation for difficulties they have experienced for years.

However, not everyone wishes to pursue formal assessment.

Others may face lengthy waiting lists or difficulties accessing diagnostic services.

Regardless of whether someone has a diagnosis, understanding their individual strengths, difficulties and support needs can still improve the way professionals work with them.

It is important, however, to distinguish between identifying characteristics that may be consistent with autism or ADHD and establishing a formal diagnosis.

Clinical observations can indicate that further exploration may be appropriate, but they should not be treated as diagnostic confirmation.

What Are the Limitations of the Research?

Although the emerging findings are interesting, it is important to recognise what the evidence does and does not establish.

Firstly, correlation does not equal causation.

Finding higher rates of autism or ADHD in certain FND populations does not prove that these conditions cause functional neurological symptoms.

Secondly, many studies involve specialist clinical populations.

Individuals attending specialist services may have more complex presentations or higher rates of co-occurring conditions than those seen in other healthcare settings.

Thirdly, diagnostic methods differ.

Some studies include individuals with formally established diagnoses, while others rely on screening measures or clinical records.

Fourthly, FND encompasses multiple presentations.

Research involving functional tic-like behaviours cannot automatically be generalised to functional seizures, functional weakness or other forms of FND.

Finally, more longitudinal research is needed.

Studies following individuals over time could help researchers better understand whether neurodevelopmental differences influence the development, persistence or recovery of functional symptoms.

My own clinical observations also have limitations.

The approximately 90% figure reflects my experience with individuals presenting with functional tic-like behaviours, rather than a systematically collected research sample.

It includes individuals with suspected but unconfirmed neurodevelopmental differences.

It may also be influenced by the type of clients referred to a specialist tic service.

Therefore, it should be understood as a clinical observation that raises questions for further investigation, rather than evidence of prevalence or causation.

Why This Matters for Families

For parents supporting a child with functional tic-like behaviours, the immediate priority is often understandably focused on the symptoms.

They want their child to feel better.

They want them to return to activities they enjoy, access education, maintain friendships and feel comfortable in everyday life.

However, it may also be helpful to explore whether there are other longstanding difficulties that have not yet been fully understood.

Does the child experience sensory sensitivities?

Do they struggle with emotional regulation?

Are there significant differences in attention, executive functioning or social communication?

Do they appear to cope in some environments but become overwhelmed afterwards?

Have they always found certain demands more difficult than their peers?

These questions are not intended to suggest that every child with functional symptoms is autistic or has ADHD.

They are intended to encourage a more complete understanding of the child's experiences.

And if neurodevelopmental differences are identified, appropriate support may improve their wellbeing and ability to participate in everyday life.

A diagnosis does not change who a child is.

But understanding their needs can change how effectively we support them.

Moving Towards a More Individualised Approach

One of the most important lessons emerging from this research is the need to move beyond a purely symptom-focused approach.

For individuals experiencing functional tic-like behaviours, appropriate FND-informed assessment and treatment remain essential.

But this should not prevent clinicians from exploring other aspects of the individual's presentation.

Autism, ADHD, sensory processing differences, anxiety, emotional awareness and environmental demands may all be relevant to understanding someone's needs.

The presence of these characteristics does not necessarily explain why functional symptoms developed.

However, recognising them may help professionals adapt their approach and provide more accessible, effective support.

This is particularly important for neurodivergent individuals who may struggle with traditional therapeutic approaches that rely heavily on verbal emotional expression, independent organisation or particular styles of communication.

Treatment should be adapted to the individual, rather than expecting the individual to adapt to a rigid therapeutic model.

Final Thoughts: Understanding the Person Behind the Symptoms

The emerging research into Functional Neurological Disorder and neurodiversity is an important and developing area.

Studies have identified notable rates of autism and ADHD among some individuals with FND, particularly those presenting with functional tic-like behaviours.

My own clinical observations have raised similar questions.

With approximately 90% of the individuals I have worked with who present with functional tic-like behaviours having either diagnosed autism and/or ADHD, or characteristics suggesting possible neurodevelopmental differences, I believe this is an area that deserves considerably more clinical attention.

However, we must be careful not to confuse clinical observations with established scientific evidence.

The research does not currently demonstrate that autism or ADHD causes FND.

What it does suggest is that neurodevelopmental differences may be relevant to understanding the wider needs of some individuals experiencing functional neurological symptoms.

For clinicians, this means remaining curious and considering the individual's developmental history and broader presentation.

For parents, it means recognising that exploring neurodevelopmental differences may provide valuable insight into their child's experiences and for individuals living with functional symptoms, it reinforces the importance of being understood as a whole person.

At TicTock Therapy & Coaching, I believe that understanding the individual is fundamental to providing meaningful support.

We need to move beyond simply asking, "How do we reduce these symptoms?"

We also need to ask, "Do we fully understand the person experiencing them?"

Because sometimes, the most important information is not found in the symptoms themselves, but in the wider experiences and needs of the individual.

And understanding those needs may be an important step towards providing the right support.

Research and References

1. Tamilson, B., Poole, N., & Agrawal, N. (2025).The co-occurrence of functional neurological disorder and autism spectrum disorder: A systematic literature review and meta-analysis.Cognitive Neuropsychiatry.https://doi.org/10.1080/13546805.2025.2452259

2. Martino, D., et al. (2023).The spectrum of functional tic-like behaviours: Data from an international registry.European Journal of Neurology.https://doi.org/10.1111/ene.15611

3. Great Ormond Street Hospital Tic Service research (2026).Autism in children and young people with functional tic-like behaviours: A retrospective cross-sectional study.https://pubmed.ncbi.nlm.nih.gov/41491157/

4. Vickers, N., et al. (2024).Comorbidity rates of autism spectrum disorder and functional neurological disorders: A systematic review, meta-analysis of proportions and qualitative synthesis.https://pubmed.ncbi.nlm.nih.gov/39152614/

5. Great Ormond Street Hospital for Children NHS Foundation Trust.Functional tics: Information for patients and families.https://www.gosh.nhs.uk/wards-and-departments/departments/clinical-specialties/psychological-and-mental-health-services-pamhs/the-tic-service/functional-tics/