PANDAS is diagnosed clinically, meaning there is no single lab test or brain scan that confirms it. Instead, a healthcare provider evaluates whether a child meets a specific set of criteria originally defined by the National Institute of Mental Health. The diagnosis hinges on a combination of sudden psychiatric symptoms, a confirmed strep infection, and the child’s age and symptom pattern over time.
The Five Diagnostic Criteria
A PANDAS diagnosis requires that a child meets all five of the following criteria:
- OCD, tics, or both. The child must have obsessive-compulsive disorder, a tic disorder, or a combination. These aren’t mild quirks. In PANDAS, the OCD or tics are typically severe and disruptive, appearing seemingly out of nowhere.
- Onset between age 3 and puberty. Symptoms must begin during childhood. PANDAS is not diagnosed in teenagers who have already gone through puberty or in adults.
- Sudden, dramatic onset. This is one of the hallmarks that separates PANDAS from typical childhood OCD or tic disorders. Parents often describe a child who was fine one day and unrecognizable the next. Symptoms arrive abruptly and can worsen just as dramatically during flare-ups.
- A confirmed strep infection within three months of symptom onset. There must be evidence of a streptococcal infection, such as a positive throat culture or a history of scarlet fever, in the weeks or months before symptoms appeared or worsened.
- Neurological abnormalities. The child shows physical signs like hyperactivity, unusual jerky movements, or other involuntary motor problems that weren’t present before.
All five criteria need to be present. A child with gradual-onset OCD or tics that developed without any link to strep would not meet the threshold, even if the symptoms themselves look similar.
Confirming the Strep Connection
Proving the link to strep is often the trickiest part of a PANDAS diagnosis. A rapid strep test or throat culture can confirm an active infection, but many children have already finished a course of antibiotics by the time psychiatric symptoms draw attention. In those cases, providers rely on blood tests that measure the immune system’s response to a past strep infection.
The two most common blood tests are the ASO titer (antistreptolysin O) and the anti-DNase B titer. Both measure antibodies your child’s body produced to fight off strep. Elevated levels suggest a recent infection even if the bacteria are no longer present. A single elevated reading can be informative, but providers often look for rising titers over two to four weeks, since that pattern more reliably points to a recent, active immune response rather than leftover antibodies from an older infection.
It’s worth noting that some children carry strep without obvious symptoms like a sore throat. These “strep carriers” can still mount an immune response that triggers PANDAS, which is why blood antibody levels matter even when there’s no memory of a recent illness.
Measuring Symptom Severity
Once a provider suspects PANDAS, they typically assess how severe the OCD or tic symptoms are. For OCD, the standard tool is the Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS), a 10-item questionnaire that scores both obsessions and compulsions on a scale from 0 to 40. Scores of 0 to 7 are considered below clinical significance. Scores of 8 to 15 indicate mild OCD, 16 to 23 moderate, 24 to 31 severe, and 32 to 40 extreme.
This scale isn’t used to confirm a PANDAS diagnosis on its own, but it serves two purposes: it documents just how suddenly and intensely symptoms arrived (a key diagnostic feature), and it gives providers a baseline for tracking whether treatment is working. Parents are typically asked to describe the child’s behavior over the past week, covering how much time obsessions and compulsions consume, how much distress they cause, and how much the child can resist them.
The Episodic Pattern
Unlike typical OCD or tic disorders, which tend to develop gradually and persist, PANDAS follows a relapsing-remitting course. Symptoms flare up sharply, sometimes improve or disappear entirely, and then return with equal or greater intensity. Each flare is often tied to a new strep exposure. This sawtooth pattern, where a child cycles between near-normal behavior and acute episodes, is a distinctive feature that helps clinicians distinguish PANDAS from other conditions.
Parents play a critical role here. A detailed timeline of when symptoms appeared, disappeared, and worsened, matched against any known illnesses, throat infections, or strep exposures in the household, gives the provider the information they need to identify this pattern. Keeping a written log of behavioral changes alongside sick days and doctor visits can be enormously helpful, especially when the diagnosis unfolds over months.
PANDAS vs. PANS
PANDAS sits within a broader category called PANS (Pediatric Acute-onset Neuropsychiatric Syndrome). The key difference is the trigger. PANDAS specifically requires a strep infection. PANS uses the same framework of sudden-onset OCD or eating restriction, but the trigger can be any infection, metabolic disturbance, or other inflammatory cause, not just strep.
If a child has the classic sudden-onset pattern but no evidence of strep, a provider may diagnose PANS instead. The evaluation process is similar, but the search for an underlying cause expands beyond strep to include other infections, immune markers, and metabolic factors. In practice, many clinicians evaluate for PANS first and narrow to PANDAS once strep is confirmed.
The Cunningham Panel
One specialized blood test, called the Cunningham Panel, measures levels of specific antibodies that target brain tissue. The idea behind it is that in PANDAS, the immune system accidentally attacks parts of the brain while fighting strep, and these antibodies are the evidence. One published study found the panel had an overall accuracy of about 86 to 90 percent in tracking whether antibody levels rose and fell alongside a child’s psychiatric symptoms, with sensitivity around 88 percent and specificity between 83 and 92 percent depending on the measure used.
That said, the Cunningham Panel remains somewhat controversial in the broader medical community. It is not universally accepted as a standalone diagnostic test, and not all insurance plans cover it. Some providers find it useful as a supporting piece of evidence, particularly when the strep connection is uncertain or when monitoring treatment response. Others view it as still needing larger, prospective studies before it can be considered a reliable diagnostic tool. If your child’s provider orders it, it will likely be interpreted alongside the clinical criteria rather than used as a definitive yes-or-no answer.
Conditions That Can Look Like PANDAS
Several other conditions share symptoms with PANDAS, and part of the diagnostic process involves ruling them out. Sydenham chorea, a neurological complication of rheumatic fever, causes involuntary movements similar to those seen in PANDAS and is also triggered by strep. The difference is that Sydenham chorea is part of a broader pattern of rheumatic fever involving the heart and joints. Tourette syndrome can look similar because it involves tics, but it typically develops gradually rather than overnight. Standard childhood OCD also overlaps in symptoms but lacks the sudden onset and episodic course tied to infections.
Providers may also consider autoimmune encephalitis, lupus affecting the brain, and thyroid disorders, all of which can cause sudden behavioral changes in children. Basic blood work, sometimes along with imaging or additional immune testing, helps sort through these possibilities. The distinguishing feature of PANDAS remains the combination of abrupt psychiatric onset, the strep link, and the relapsing-remitting course. When all five criteria line up, the diagnosis becomes clear even without a single confirmatory lab test.