PANS and PANDAS in Children: When Behaviour Changes Suddenly

How infections, the immune system and inflammation affect your child's brain and behaviour.

Imagine your child going to bed one evening and waking up the next morning seeming like a completely different person. Suddenly, they're overwhelmed by anxiety. They may develop unusual fears, obsessive thoughts or repetitive behaviours. They might refuse foods they've always enjoyed, become unusually aggressive, or experience emotional outbursts that seem to come from nowhere. For some families, these changes happen almost overnight. For others, symptoms develop over several days. It's frightening, confusing and exhausting, particularly when there seems to be no obvious explanation.

While sudden behavioural changes can have many causes, two conditions worth understanding are PANS and PANDAS.

These conditions describe a sudden onset of neurological and psychiatric symptoms in children. Understanding the possible connection between the immune system and the brain is an important part of recognising when a child needs further medical investigation.

What are PANS and PANDAS?

PANS stands for Paediatric Acute-onset Neuropsychiatric Syndrome.

It's a condition in which a child suddenly develops obsessive-compulsive symptoms (OCD) or severely restricted eating, together with other neurological or behavioural symptoms. These additional symptoms may include anxiety, aggression, sleep disturbances, emotional outbursts, sensory sensitivities, deterioration in handwriting, bedwetting or increased urinary frequency, and changes in learning or development. PANS can occur following an infection, although an infection does not have to be identified for a diagnosis. It is thought that, in some children, symptoms may develop when the immune system becomes overactive or dysregulated. This means the immune system may produce an unusually strong or poorly controlled inflammatory response, potentially affecting how the brain functions. Infections are just one possible trigger.

PANDAS stands for Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections.

PANDAS describes a more specific group of symptoms, particularly sudden-onset OCD or tics, that are thought to be associated with Group A streptococcal infections.

These are the bacteria responsible for illnesses such as strep throat and scarlet fever.

The main difference is that PANDAS is specifically associated with streptococcal infection, while PANS is not limited to one possible trigger.

Recognising the signs of PANS and PANDAS

One of the most important features of PANS is how quickly symptoms appear. A child who was previously coping well may suddenly struggle with everyday activities, school, friendships or family life.

Symptoms can include:

• Obsessive-compulsive behaviours: Repeated checking, washing, counting, arranging objects or needing things done in a particular way.

• Severe anxiety: Sudden fears, panic attacks or becoming extremely distressed when separated from a parent.

• Emotional outbursts: Intense anger, irritability, aggression or uncontrollable crying.

• Restricted eating: Suddenly refusing food because of fears about choking, contamination, vomiting or other concerns.

• Tics: Repeated movements or sounds, such as blinking, facial movements, throat clearing or grunting.

• Changes in sleep: Difficulty falling asleep, frequent waking or new sleep disturbances.

• Sensory sensitivities: Becoming unusually sensitive to sounds, lights, clothing or touch.

• Developmental regression: Losing previously established skills or behaving much younger than expected.

• Changes in learning: Suddenly struggling with handwriting, concentration, memory or schoolwork.

• Urinary symptoms: Needing to urinate frequently or suddenly experiencing bedwetting.

  
  

Not every child experiences all these symptoms.

For PANS, the usual diagnostic criteria require a sudden onset of OCD or severely restricted eating, together with at least two other groups of symptoms. Other possible medical explanations must also be considered. A child who develops aggression, anxiety or tics does not automatically have PANS or PANDAS. However, a dramatic change in behaviour deserves careful attention, particularly when several symptoms appear together.

How can an infection affect the brain?

Most of us think about infections as something that causes a sore throat, fever, cough or upset stomach. But infections activate the immune system. When the body detects bacteria or viruses, immune cells release chemical messengers called cytokines. These help coordinate the body's defence against infection. Cytokines are important because they tell immune cells where they're needed and help control inflammation. Inflammation is a normal part of the body's defence system. It helps the body fight infections, respond to threats and repair damaged tissue.

However, problems can arise when inflammation becomes excessive, lasts too long or affects sensitive tissues, including the brain. An unusually strong or poorly regulated immune response following an infection is one proposed explanation of why some children develop sudden neurological and behavioural symptoms, while others recover without complications. This abnormal immune response may contribute to neuroinflammation (inflammation affecting the brain), potentially disrupting normal brain function and causing sudden changes in behaviour, emotions and neurological symptoms.

This is one of the leading theories being investigated in PANS and PANDAS, although the exact mechanisms are not yet fully understood.

Molecular mimicry: When the immune system gets confused

One possible explanation involves a process called molecular mimicry. Normally, the immune system produces antibodies that recognise and help fight harmful bacteria or viruses.

Sometimes, parts of a microorganism look very similar to proteins found in our own bodies. This can confuse the immune system, causing antibodies produced to fight an infection to mistakenly recognise and attack healthy tissue. This process is called molecular mimicry. In PANDAS, antibodies produced in response to a streptococcal infection may mistakenly react with proteins in the brain, particularly in areas involved in movement, emotions and behaviour.

Neuroinflammation: When the brain's immune system becomes activated

The brain has its own immune defence system. One important part of this system involves specialised cells called microglia. Microglia act a little like security guards. They constantly monitor the brain, help remove damaged material and respond to signs of injury or infection. When the brain detects a threat, microglia can become activated and release inflammatory chemicals. This response is normally protective.

However, excessive or prolonged activation may interfere with how brain cells communicate. Inflammation within the brain or nervous system is called neuroinflammation.

Why does this matter for behaviour?

Our thoughts, emotions, movements and behaviours depend on communication between billions of nerve cells in the brain. These cells use chemical messengers, called neurotransmitters, to send signals to one another. Some familiar neurotransmitters include dopamine, serotonin and glutamate.

Inflammation can interfere with how nerve cells communicate, potentially affecting the production, release and activity of neurotransmitters. Researchers are investigating whether these changes contribute to symptoms associated with PANS and PANDAS, including anxiety, obsessive-compulsive behaviours, emotional outbursts and tics.

However, there is currently no established neurotransmitter pattern that can reliably diagnose either condition.

Can children with autism also develop PANS or PANDAS?

Yes! Having autism does not exclude a child from developing PANS or PANDAS. This is an important distinction because some symptoms can overlap. Children with autism may already experience sensory sensitivities, anxiety, repetitive behaviours, sleep difficulties or restricted eating.

However, a sudden and significant change from a child's usual behaviour should not automatically be attributed to autism.

For example, a child who has always enjoyed a particular food may suddenly refuse to eat because they're frightened of choking. Another child who previously managed school may develop severe separation anxiety, new repetitive behaviours and difficulty concentrating within a few days. These changes warrant investigation.

It's also important to remember that children with autism may experience behavioural changes because of pain, constipation, sleep deprivation, medication effects, seizures, anxiety or other medical conditions. A thorough assessment should consider these possibilities rather than assuming one particular cause.

What about the gut–brain–immune connection?

The gut and brain communicate constantly through nerves, hormones and immune signals. This communication is often called the gut–brain axis. The digestive system also contains a large proportion of the body's immune cells, making the gut an important part of immune regulation. Trillions of microorganisms live within our digestive system. Together, they form the gut microbiome. These microorganisms help break down food, produce useful substances and interact with immune cells.

Some gut bacteria produce short-chain fatty acids, including butyrate, which help support the intestinal lining and regulate aspects of immune activity.

There is an increasing amount of interested in how the microbiome may influence inflammation, immune responses and brain function.

How are PANS and PANDAS diagnosed?

This is the shady part. There is currently no single blood test, brain scan or laboratory marker that can confirm PANS or PANDAS. Diagnosis relies on a careful medical history, assessment of symptoms and consideration of other possible causes.

A clinician will usually want to understand:

• Exactly when the symptoms began.

• Whether they developed suddenly or gradually.

• Which symptoms appeared together.

• Whether the child (or a close contact) had a recent infection.

• Whether symptoms improve and then return.

• Whether there are other neurological or physical symptoms.

Depending on the child's presentation, investigations may include testing for a suspected streptococcal infection, blood tests or referral to a relevant specialist.

Two blood tests commonly used to investigate recent streptococcal infection are ASO (antistreptolysin O) and anti-DNase B. These measure antibodies produced in response to Group A streptococcal bacteria. Elevated levels can indicate recent or previous infection, although antibodies may remain elevated for months. A negative result does not exclude PANDAS, and a positive result does not confirm it. Results must be interpreted alongside the child's symptoms and clinical history.

The aim is not simply to attach a diagnosis to a child's behaviour. It's to understand what has changed and identify and address any biomedical imbalances.

How are PANS and PANDAS treated?

Treatment depends on the child's symptoms, lab findings if needed, and overall health, remembering that every child is a unique individual. Every child needs an individualised assessment and plan to move forward.

Addressing infections and immune activation

Identifying and treating infections is an important part of managing suspected PANS and PANDAS. Confirmed bacterial infections, including Group A streptococcal infections, may require antibiotic treatment.

However, treatment should also consider factors that may be contributing to ongoing immune activation and inflammation. This includes identifying potential sources of infection or immune activation, addressing nutritional deficiencies and supporting normal immune regulation. Nutrients such as vitamin D, zinc, vitamin A and omega-3 fatty acids play important roles in immune function and inflammatory regulation. Certain herbal compounds, including curcumin and boswellia, also have anti-inflammatory properties. From a functional medicine perspective, the aim is to identify and address factors that may be placing additional pressure on the immune system, while supporting the body's ability to regulate inflammation and recover. Nutritional and herbal interventions should be individualised.

Supporting nutrition and general health

Good nutrition is important for brain function, immune regulation and overall wellbeing.

Children experiencing severe anxiety or restricted eating may struggle to consume enough energy, protein, vitamins and minerals. Addressing nutritional deficiencies, digestive discomfort, poor sleep and other health concerns can therefore be an important part of supportive care. In a personalised functional medicine approach, attention may also be given to digestive health, dietary adequacy and factors affecting a child's ability to recover from illness.

When should parents seek medical advice?

If your child develops sudden and significant changes in behaviour, particularly alongside new OCD symptoms, food restriction, tics or neurological changes, get in contact with a knowledgable healthcare provider. It can help to keep a record of when symptoms began, recent illnesses, sleep changes and any new behaviours. Photos or short videos of unusual movements may also help clinicians understand what you're observing.

Seek urgent medical attention if your child develops seizures, confusion, a reduced level of consciousness, unusual weakness, rapidly worsening neurological symptoms or an inability to maintain adequate food and fluid intake. These symptoms can indicate medical conditions requiring immediate assessment.

Looking beyond the behaviour

One of the most important lessons from PANS and PANDAS research is that behaviour and physical health are closely connected. The immune system, nervous system and brain do not work independently. They communicate constantly, and changes in one system can influence another.

We still have much to learn about PANS and PANDAS. Not every sudden behavioural change is caused by inflammation, and not every child with these symptoms has an immune-related disorder. But when a child experiences a dramatic change in their behaviour, it's important to investigate rather than simply assume the behaviour is intentional, psychological or part of an existing developmental condition.

Behaviour can be a form of communication, particularly when children cannot easily explain what they're experiencing.

Recognising changes, asking questions and seeking appropriate medical support can help families understand what may be happening and identify the best way forward.

Amanda Downsborough, BSc, PGDip, MSc, FMAPS

Functional & Nutrigenomic Medicine Practitioner

Brain Kids – www.brainkids.com.au

About the Author

Amanda Downsborough, BSc, PGDip, MSc, FMAPS, is a Functional and Nutrigenomic Medicine Practitioner specialising in autism and child neurodevelopment. Through her practice, Brain Kids, Amanda combines functional medicine and neuroscience to uncover the biochemical and environmental factors affecting children’s health. Her work empowers families with science-based strategies to support brain balance, behaviour, and lifelong wellbeing.

Disclaimer

This information is provided for educational purposes only and is not intended as a

substitute for medical advice, diagnosis, or treatment. Always seek the advice of a

qualified healthcare provider with any questions regarding a medical condition or before

making changes to your or your child’s care plan.