As awareness of neurodivergence continues to grow, many families are discovering that autism and ADHD often come with additional physical health challenges that may have previously been overlooked or misunderstood.

For some children and adults, challenges such as chronic fatigue, dizziness, digestive difficulties, pain, allergies, sensory sensitivities and fluctuating energy levels may not be separate concerns at all. Increasingly, researchers and clinicians are recognising connections between neurodivergence and conditions including Mast Cell Activation Syndrome (MCAS), Postural Orthostatic Tachycardia Syndrome (POTS), and Hypermobility Spectrum Disorders (HSD) and Hypermobile Ehlers-Danlos Syndrome (hEDS).

While every individual is unique, understanding these connections can help families make sense of symptoms, seek appropriate support, and develop greater self-compassion.

What is Mast Cell Activation Syndrome (MCAS)?

Mast cells are a normal part of our immune system. They help protect us by releasing chemicals such as histamine when they detect potential threats.

In people with MCAS, mast cells can become overly sensitive and release these chemicals inappropriately or excessively. This can create symptoms throughout the body, often affecting multiple systems at once.

Common symptoms of MCAS may include:

• Frequent allergic-type reactions
• Itching, hives or unexplained rashes
• Flushing or sudden warmth
• Digestive difficulties such as nausea, reflux or abdominal pain
• Headaches and migraines
• Fatigue
• Brain fog
• Sensitivity to foods, medications or environmental triggers
• Respiratory symptoms such as wheezing or congestion

Because symptoms can vary significantly from person to person, MCAS is often difficult to recognise and may take time to diagnose.

What is POTS?

Postural Orthostatic Tachycardia Syndrome (POTS) is a condition affecting the autonomic nervous system—the system responsible for regulating many automatic body functions including heart rate, blood pressure, digestion and temperature regulation.

When someone with POTS moves from lying down or sitting to standing, their heart rate increases significantly, often leading to a range of symptoms.

Common symptoms of POTS may include:

• Dizziness or light-headedness when standing
• Rapid heartbeat
• Fainting or near-fainting episodes
• Extreme fatigue
• Exercise intolerance
• Brain fog and concentration difficulties
• Headaches
• Digestive symptoms
• Temperature regulation difficulties
• Nausea

Many children and adults with POTS describe feeling as though their energy levels fluctuate dramatically throughout the day.

What is Hypermobility Syndrome?

Many people think of hypermobility simply as being “double-jointed” or unusually flexible. However, for some individuals, hypermobility affects far more than their joints.

Hypermobility Spectrum Disorders (HSD) and Hypermobile Ehlers-Danlos Syndrome (hEDS) involve differences in connective tissue, which provides support throughout the body.

Common symptoms of hypermobility may include:

• Joint pain
• Frequent sprains or injuries
• Joint instability
• Fatigue
• Muscle aches
• Poor proprioception (body awareness)
• Digestive difficulties
• Headaches
• Coordination challenges
• Easy bruising
• Heavy and painful menstrural cycles

For some people, symptoms are mild. For others, hypermobility can significantly affect daily life, physical comfort and energy levels.

How Are These Conditions Connected?

Researchers have observed a notable overlap between MCAS, POTS and hypermobility conditions.

Although the exact mechanisms are still being investigated, these conditions frequently appear together.

One theory suggests that differences in connective tissue associated with hypermobility may affect blood vessels and autonomic nervous system function, contributing to POTS symptoms. Mast cell activity may also influence inflammation, vascular regulation and nervous system responses, creating further overlap between MCAS and POTS.

Many of us working as clinicians now refer to this as a “triad” because these three conditions are so commonly seen together.

Not everyone with one condition will develop the others. However, when symptoms seem to span multiple body systems, it can be helpful to explore whether there may be an underlying connection.

What Does This Have to Do with Autism and ADHD?

Many neurodivergent individuals report experiences that align with one or more of these conditions.

Emerging research suggests higher rates of hypermobility, autonomic nervous system differences and immune system dysregulation among autistic and ADHD populations compared with the general population.

While we do not yet fully understand why these connections exist, several theories are being explored, including:

• Shared genetic factors
• Differences in connective tissue development
• Nervous system regulation differences
• Immune system variations
• Sensory processing differences that increase awareness of physical symptoms

It is important to remember that autism and ADHD are not caused by MCAS, POTS or hypermobility, nor do these conditions occur in every neurodivergent person.

Rather, they may represent interconnected ways in which the nervous system, immune system and connective tissues develop and function.

Looking Beyond Behaviour

For neurodivergent children especially, physical symptoms can sometimes be mistaken for behavioural challenges.

A child who appears anxious may actually be experiencing dizziness from POTS.

A child who struggles with concentration may be dealing with fatigue, pain or brain fog.

A child who seems irritable may be coping with digestive discomfort, headaches or mast cell activation symptoms.

When we view behaviour as communication, we open the door to understanding what the body may be trying to tell us.

A Whole-Person Approach

Recognising the potential links between neurodivergence, MCAS, POTS and hypermobility encourages a more holistic understanding of health.

Rather than viewing physical, emotional and sensory experiences as separate, we can begin to appreciate how closely connected they often are.

For families navigating these complexities, knowledge can be empowering. Understanding the bigger picture may help explain experiences that previously felt confusing or disconnected and support more tailored care and accommodations.

Every person’s experience will be different, and no single explanation fits everyone. However, listening carefully to both the body and the nervous system can often provide valuable clues.

Learn More About Hypermobility and MCAS

One particularly interesting area of ongoing research is the relationship between hypermobility and Mast Cell Activation Syndrome. Many individuals with hypermobility report symptoms commonly associated with mast cell activation, and researchers continue to explore the biological links between connective tissue differences and immune system function.

In future blog posts, we’ll take a closer look at hypermobility and MCAS, exploring why these conditions frequently occur together and what families may wish to know when seeking support.