PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections) is a medical condition where a common childhood infection triggers the sudden onset of severe behavioral and neurological symptoms. The disorder links an immune reaction to Group A Streptococcus (GAS) bacteria, the cause of strep throat, to dramatic changes in a child’s mental state. Recognizing the unique and acute presentation of PANDAS is important for appropriate clinical evaluation.
Understanding the Autoimmune Trigger
The development of PANDAS symptoms begins with an immune response to a Group A Strep infection. The body’s immune system creates antibodies to fight the invading bacteria, which possess a molecule called N-acetyl-beta D-glucosamine. The immune system mistakenly attacks healthy brain tissue due to a phenomenon called molecular mimicry.
Molecular mimicry occurs because the bacterial molecule closely resembles certain proteins found in the child’s own brain cells. The misguided antibodies cross-react and target the basal ganglia, a deep brain structure that helps control movement, emotion, and behavior. This autoantibody attack on the basal ganglia causes inflammation and disrupts normal neuronal functioning, resulting in the sudden onset of neuropsychiatric symptoms. This mechanism is similar to how strep infections can trigger rheumatic fever.
Identifying the Core Behavioral Symptoms
The hallmark of PANDAS is the sudden, severe, and dramatic emergence of symptoms, often described as happening “overnight.” This acute onset distinguishes the condition from the gradual development seen in typical childhood psychiatric disorders. The most commonly recognized and defining behavioral symptoms involve obsessive-compulsive disorder (OCD) and tics.
A child may develop new, intense obsessions and compulsions that interfere significantly with their daily life. These OCD symptoms can include contamination fears, excessive washing rituals, or a sudden need for symmetry and order. The child may also present with new motor or vocal tics, which are involuntary, repetitive movements or sounds. Motor tics range from eye-blinking to complex movements, while vocal tics may manifest as throat-clearing or grunting.
Children often experience severe anxiety, particularly separation anxiety. They may become extremely moody, showing emotional lability with sudden bursts of laughing or crying, or episodes of intense irritability and rage. Parents frequently observe a regression in behavior. Other common symptoms include:
- Decline in fine motor skills, often resulting in difficulty with legible handwriting (dysgraphia)
- Sleep disturbances
- Sudden urinary issues, such as frequent daytime urination or bedwetting
- Clinginess or using “baby talk”
Diagnostic Requirements and Episodic Nature
PANDAS is a clinical diagnosis, based on a doctor’s assessment of the symptoms and the child’s medical history rather than a single laboratory test. Clinicians use a set of five defined criteria to confirm the diagnosis. The first requirement is the presence of a tic disorder, OCD, or both, severe enough to affect the child’s ability to function at their pre-illness level.
The second criterion specifies a pediatric onset, meaning the symptoms must first appear between the ages of three and puberty. Third, the condition is defined by an acute onset and an episodic course, where symptoms appear dramatically and then wax and wane over time. The dramatic onset is often so sudden that parents can pinpoint the exact day the child changed.
The fourth requirement establishes a temporal association with a Group A Strep infection, meaning the sudden onset or worsening of symptoms must closely follow a documented strep infection, usually within three months. The fifth criterion is the presence of neurological abnormalities during symptom exacerbations. These can include physical hyperactivity, motor restlessness, or involuntary, jerking movements known as choreiform movements. The episodic nature of the disorder means symptoms can disappear for extended periods only to reappear or worsen following a subsequent strep exposure.