what are pans & pandas?
PANDAS stands for Paediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections. PANS stands for Paediatric Acute-onset Neuropsychiatric Syndrome.
They're both a mouthful, so let's break down what they actually mean in plain English.
Both conditions describe what happens when a child's immune system, the very system that's supposed to protect them from infection, accidentally turns on their own brain and causes sudden, dramatic changes in behaviour and mental health.
PANDAS is the more specific term, used when the trigger is clearly a strep throat infection (Group A Streptococcus, the same bug that causes ordinary strep throat).
PANS is the broader umbrella, used when similar symptoms appear after other infections, or sometimes when no clear trigger can be found.
It's important to understand that PANS and PANDAS are not primarily psychiatric conditions.
They are inflammatory brain conditions that produce psychiatric symptoms, which is a crucial distinction, because it means treating the immune trigger, not just the behaviour, is central to recovery.
inside the
basal ganglia
Deep inside the brain, there is a group of structures called the basal ganglia. Most people have heard of the brain's memory centre (the hippocampus) or its emotional centre (the amygdala), but the basal ganglia is less well known, even though it's doing something incredibly important all the time.
Think of the basal ganglia as the brain's filter. Its job is to let through the thoughts and actions that are helpful, and to suppress (push down and block) the ones that aren't. It's what allows you to have an unwanted thought and then let it go, rather than being stuck on it.
In healthy people, this filtering system runs silently in the background. You don't notice it working. But when it's disrupted, as happens in obsessive-compulsive disorder (OCD),
Tourette's syndrome, and, as we're now discovering, in PANS and PANDAS, the filter breaks down, and unwanted thoughts and urges flood through repeatedly.
how do these conditions occur?
When the immune system gets confused
When your child gets a strep throat infection, their immune system does exactly what it's supposed to do: it identifies the strep bacteria and makes antibodies to attack and destroy them. In most children, this works perfectly and the infection clears.
But in some children, something goes wrong. The proteins on the surface of strep bacteria look surprisingly similar to proteins found on the surface of certain nerve cells in the basal ganglia.
When the immune system makes antibodies to target the strep, those antibodies can accidentally recognise and attach to nerve cells in the brain instead.
This is called molecular mimicry. The bacterium is essentially 'mimicking' the body's own proteins, which fools the immune system into attacking the wrong target.
It's similar to what happens in rheumatic fever, where antibodies made against strep accidentally attack the heart. In PANDAS, the same type of case of mistaken identity targets the basal ganglia.
What those antibodies do to the brain
Once these antibodies attach to cells in the basal ganglia, they activate a chain reaction inside the nerve cells that causes them to produce too much dopamine, a chemical messenger that plays a central role in controlling movement, habits, and motivation.
Too much dopamine in the basal ganglia essentially breaks the filtering system we talked about earlier. The filter gets overwhelmed, and thoughts and urges that should be quickly suppressed can't be held back.
The result is compulsive behaviours, intrusive thoughts, and tics.
Research has shown that injecting these specific antibodies from PANDAS patients into the brains of mice produces OCD-like behaviours in those mice, which is strong evidence that the antibodies are directly causing the symptoms.
The symptoms appear almost overnight
One of the most striking and distressing things about PANS and PANDAS is how fast the symptoms come on. Parents often describe knowing the exact day, even the exact hour, when their child changed. A child who was perfectly well on Monday morning might be severely affected by Monday night.
This is completely different from typical OCD or anxiety, which build gradually over months. The sudden-onset is one of the most important clues that something medical, not just psychological, is happening. It's the immune system triggering inflammation in the brain, and inflammation can act fast.
The infection also lets the antibodies in
Normally, the blood-brain barrier we mentioned in the Lyme disease section keeps antibodies out of the brain. But strep infections, like many infections, can temporarily weaken this barrier. This is thought to be the reason why symptoms flare up during or just after an infection: the barrier is weakened at exactly the moment when the body is producing the highest levels of those cross-reactive antibodies.
what does it look like?
The symptoms of PANS and PANDAS go far beyond OCD. While compulsive behaviours and intrusive, repetitive thoughts are the core features, they are almost always accompanied by other sudden changes.
Extreme separation anxiety is very common: a child who was previously confident suddenly refusing to be away from a parent for a moment.
So is emotional dysregulation: intense, prolonged emotional outbursts that seem completely out of character. Many children regress to behaviours they'd grown out of years earlier, such as bedwetting or baby talk.
Handwriting, maths, and memory can all deteriorate noticeably. Sensory sensitivities can become extreme: clothing that was comfortable becomes unbearable, sounds that were fine become overwhelming. Sleep is often severely disrupted.
For parents watching this unfold, it can feel like their child has been replaced by someone else in a short space of time. That experience is not an exaggeration. The changes really can be that dramatic, and that fast.
how is it treated?
Because PANS and PANDAS are immune-mediated conditions, caused by an immune system that has gone off course, the most effective treatments target the immune system, not just the symptoms.
Antibiotics are the foundation of treatment in PANDAS. By clearing the strep infection (and preventing future ones with ongoing antibiotic prophylaxis), the trigger for the immune response is removed. Many children improve significantly once the infection is treated.
For more severe cases, treatments that directly reduce or retrain the immune response are used. Intravenous immunoglobulin (IVIG) involves giving a large dose of antibodies from healthy donors. These help to dilute and neutralise the harmful antibodies and calm the immune response. Controlled trials have shown it to be effective in PANDAS.
Therapeutic plasma exchange, a process where the blood is filtered to remove the harmful antibodies, can produce rapid, dramatic improvements in severely affected children. When a child has a dramatic response to plasma exchange, it is itself strong evidence that antibodies are the cause of their symptoms.
Alongside these immune treatments, psychological support, particularly cognitive behavioural therapy (CBT) adapted for OCD, can be helpful, especially during recovery.
current research
Better tests
One of the biggest challenges in PANS and PANDAS is that there is no single blood test that can confirm the diagnosis. Research teams are working to develop panels of antibody tests that can identify the specific antibodies involved, making diagnosis much more straightforward.
Understanding who is at risk
Not every child who gets strep throat develops PANDAS. Most don't. This suggests some children are genetically more susceptible. Identifying those children could one day allow for earlier monitoring and faster treatment when a trigger occurs.
Long-term outcomes
The good news is that many children with PANS and PANDAS do recover, particularly when the condition is recognised and treated early. Research into long-term outcomes is helping to build a clearer picture of what recovery looks like, and what helps children get there.
