“PANDAS, PANS and Autoimmune Encephalitis: Sudden Anxiety, OCD or Behaviour Change in Children and Adults

If Nothing Has Worked So Far, This Might Be Why – PANDAS & PANS

A child is fine, then within days thry are not. New OCD. New tics, rage or anxiety with no obvious cause. Parents describe it to me the same way almost every time, like something switched off overnight.

The phenomenon of PANDAS and PANS is often overlooked, yet it can manifest in various distressing symptoms.

Or it’s an adult with anxiety that will not go away no matter how much therapy they do, how many meditations or mindfulness exercises they do. ADHD that used to be manageable and suddenly isn’t, when medication that worked fine for years and has stopped working, or is now making things worse.

This gets treated as a mental health problem because that’s what it looks like. Underneath it sometimes, it’s an infection the body never properly switched off from. Susannah Cahalan wrote about exactly this in Brain on Fire: weeks spent treated as though she was having a psychotic breakdown. Doctors eventually found antibodies attacking her NMDA receptors, a receptor the brain relies on for memory and learning. What triggered her immune system was never  discovered. Unlike around 50% of people with this illness, she didn’t have the ovarian teratoma usually behind it.

The pattern I look for

In children this has a name. PANDAS when it follows strep specifically, PANS when the trigger is broader. What marks it out isn’t the symptoms on their own, it’s how fast they arrived. Days, not months.

In adults the same process usually sits under autoimmune encephalitis instead. Sudden OCD, anxiety, mood change or brain fog turning up after a bout of strep throat, glandular fever, a Lyme infection, or a virus, COVID included.

One thing worth knowing at any age. If a stimulant that used to work suddenly stops, or starts making things worse, that’s not a reason to increase the dose. It’s a reason to ask what’s driving it that hasn’t been resolved.

Why it gets missed

Because when it presents as psychiatric, it gets treated as psychiatric: therapy, medication, more therapy, while the actual driver keeps being ignored Cahalan’s own doctors nearly missed it too, and she had access to some of the best care available.

The immune system can produce antibodies that end up affecting the brain directly, and some of these are now understood well enough to explain specific symptoms rather than a vague chemical imbalance story. I truly believe from having seen many patients with neurological autoimmune presentations, that there are countless antibodies that haven’t been studied, discovered, and that we cannot test for which is why this process can be extremely frustrating. One antibody linked to anxiety seems to make it harder for the brain to properly register that a threat has passed, even when someone understands that logically. That would explain why therapy alone hasn’t worked. Not because the therapist was not good enough, or because it was the wrong type of therapy, but because the process talking therapies rely on to facilitate change may itself be disrupted.

What I test for

Anti-NMDA receptor antibodies are what were driving Cahalan’s illness, the most common form of autoimmune encephalitis worldwide. They target a receptor the brain needs for memory and learning. In adults it mainly affects young women, and around half have an underlying ovarian teratoma, though not all, as Cahalan didn’t. 

In children it’s one of the most common causes of autoimmune encephalitis, but the early signs are often different: movement disorders, behavioural changes and disturbed sleep, speech regression, rather than the psychiatric symptoms that tend to dominate in adults.

Anti-dopamine receptor antibodies (D1 and D2) are the ones most linked to PANDAS and PANS in children and are often triggered by Streptococcus A infection. 

D2 antibodies are associated with Sydenham chorea, the involuntary movements sometimes seen after strep infection, while D1 antibodies are linked to the sudden OCD and repetitive behaviours that define a PANDAS presentation. In adults, D1 receptor antibodies have been associated with treatment-resistant OCD, though this is far less studied than in children.

Anti-CASPR2 antibodies affect the peripheral nerves, the autonomic system and the limbic system. In adults this usually shows up in middle-aged to older men, sometimes alongside a thymoma, and can cause severe anxiety, insomnia, OCD-type symptoms and autonomic problems like excessive sweating or a racing heart, sometimes without ever reaching full diagnostic criteria for encephalitis. In children it’s rarer, but similar anxiety, behavioural change and OCD-type features have been described, often with sleep disturbance alongside.

Anti-LGI1 antibodies particularly affect the hippocampus. A distinctive early sign is very brief, frequent seizures affecting the face and arm on one side, sometimes appearing weeks before anything else. In adults this mainly affects older adults and often comes with low sodium levels, a useful clue for doctors. It’s rare in children and tends to overlap with other encephalitis presentations rather than showing that same early seizure pattern.

Anti-GABA-B receptor antibodies reduce the brain’s inhibitory tone, particularly in the hippocampus. GABA-B receptors work differently to the GABA-A receptors that benzodiazepines and standard anxiolytics act on, so when antibodies disrupt this specific pathway, those medications don’t help the way they normally would, a distinct mechanism, not just a stronger dose problem. In adults, the seizures are usually the most prominent feature, often frequent and resistant to standard anticonvulsants, alongside memory impairment, confusion, and psychiatric symptoms including anxiety, mood change and behavioural disturbance. It has a strong paraneoplastic association with small cell lung cancer, and a smoking history is a common background feature in these cases, so cancer screening is a standard part of the workup once this antibody is identified. It’s rare in children, and where it does occur, it tends to appear without the cancer association seen in adults.

Anti-glycine receptor antibodies affect the body’s main inhibitory signal in the brainstem and spinal cord, the system that normally dampens down startle responses, muscle activity and pain signals. This can produce muscle rigidity, an exaggerated startle response, and anxiety that doesn’t respond to standard anxiety medication, because those work through a different pathway entirely. It’s more common in middle-aged adults, and in children the movement disorder features tend to be more prominent than in adults.

Thyroid antibodies (anti-TPO and anti-TG) are usually linked to autoimmune thyroid disease, but they’re also associated with Hashimoto encephalopathy, which can occur even when thyroid function tests are completely normal. It can cause confusion, seizures, psychiatric symptoms and mood change. It affects both adults and children, and is often missed because normal thyroid results are wrongly taken to rule it out and women are rarely getting thyroid ultrasonds (something I highly recommend as this can pick up early structural changes before antibodies become positive).

A less common but well-documented presentation is cerebellar, where anti-thyroid peroxidase antibodies cross-react with cerebellar tissue, sometimes described as anti-cerebellar antibodies, producing progressive ataxia, unsteady gait and coordination difficulties rather than the confusion and seizures seen in the classic form. Imaging can show cerebellar atrophy.

What actually helps

What I bring is the wider testing, nutrient depletion, gut and inflammatory markers, immune function using whatever modalities are relevant to you, including functional testing, nutrition and herbal medicine.

Diet comes first. A gluten and dairy free diet is one of the most important things I bring in for both children and adults with this pattern. Both proteins cross-react with multiple brain proteins and  provoke an already overactive immune response. Nutrient correction sits alongside that, supporting a nervous system that’s already under strain. Herbs can also make a big difference for example, where someone isn’t responding to anxiolytic medications to regulate response.

I also use hyperbaric oxygen, red and near infrared light. The research on these for calming neuroinflammation is promising and clinically, I see huge benefits.

If you’ve watched yourself or your child change suddenly and nobody’s had a proper answer, get it looked into properly rather than living around it. Book a preliminary call if you want to talk it through.