Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS) is a clinical diagnosis describing a sudden, severe onset of neuropsychiatric symptoms in children following an infection with Group A Beta-Hemolytic Streptococcus (GABHS). The syndrome is thought to occur when the body’s immune response to the strep bacteria mistakenly targets the basal ganglia in the brain, leading to inflammation and symptoms. This theory of molecular mimicry, where antibodies attack both the pathogen and the host’s brain tissue, connects PANDAS to other post-streptococcal illnesses like rheumatic fever.
The National Institute of Mental Health (NIMH) established five criteria for diagnosis:
- The presence of obsessive-compulsive disorder (OCD), a tic disorder, or both, severe enough to disrupt daily life.
- The onset of these symptoms must be unusually abrupt and dramatic.
- An episodic course of the illness, where symptoms reappear or increase in severity with subsequent strep infections.
- Onset must occur during childhood, specifically between three years of age and puberty.
- A clear association with a Group A Streptococcal infection, confirmed by a positive test or elevated antibody titers.
Factors Complicating Prevalence Data
Determining the exact commonality of PANDAS is difficult, contributing to the wide range of estimates available. PANDAS is a clinical diagnosis relying entirely on patient history and observation, as there is no single, definitive laboratory test or biomarker to confirm its presence. This reliance on subjective criteria and temporal association makes large-scale epidemiological tracking inconsistent.
A significant hurdle is the frequent misdiagnosis and resulting underreporting. PANDAS symptoms—including tics, anxiety, mood changes, and attention difficulties—closely overlap with established conditions like standard OCD, Tourette’s syndrome, and Attention-Deficit/Hyperactivity Disorder (ADHD). Consequently, children meeting PANDAS criteria often receive a diagnosis of a primary psychiatric illness, removing them from PANDAS prevalence counts.
The medical community also continues to debate the classification and recognition of PANDAS, slowing the standardization of diagnostic practice. Researchers have not conclusively proven the link between the strep infection and the neuropsychiatric symptoms for every case, leading some clinicians to remain hesitant about the diagnosis. Data collected across different clinical settings can vary widely based on the diagnostician’s familiarity with the syndrome and adherence to the NIMH criteria.
Current Estimates of PANDAS Commonality
Since PANDAS is not tracked through mandatory public health surveillance, its commonality must be estimated from population studies of related conditions. The figures reported in literature and by advocacy groups vary significantly, reflecting the diagnostic complexities of the syndrome. A widely cited estimate from the PANDAS Network suggests the condition may affect approximately 1 in 200 children in the United States.
Researchers also estimate commonality by examining what percentage of childhood OCD or tic disorder cases are strep-triggered. Some early estimates proposed that PANDAS could account for as much as 25% of children diagnosed with sudden-onset OCD and tics. However, other studies examining clinical populations have reported a much smaller fraction, finding that only a small percentage of pediatric OCD patients meet the PANDAS criteria.
More recent research attempting to determine annual incidence provides more conservative figures, often combining PANDAS with the broader PANS category. One study in primary care populations estimated the annual incidence of PANDAS/PANS combined to be around 1 in 11,765 for children aged three to twelve. Other academic estimates for PANDAS alone have ranged closer to 1 per thousand children.
PANDAS Versus PANS: A Broader Context
PANDAS is a specific subset of a larger umbrella diagnosis known as Pediatric Acute-onset Neuropsychiatric Syndrome (PANS). While PANDAS is defined by its exclusive association with a Group A Streptococcal infection, PANS encompasses all cases of acute-onset OCD or severe food restriction triggered by any infection or inflammatory process.
This broader PANS category includes cases initiated by other common pathogens, such as Lyme disease, influenza, mycoplasma, or non-infectious causes like metabolic disturbances. All cases of PANDAS are considered a type of PANS, but not all PANS cases are PANDAS. The relatively narrow focus on a single bacterial trigger means PANDAS is inherently less common than the overall PANS population.
The distinction is important because the prevalence of PANS is much higher, capturing the full range of post-infectious and inflammatory triggers. This relationship explains why statistics for PANDAS alone are lower than for the general population of children experiencing acute-onset neuropsychiatric symptoms. The differing triggers also influence treatment protocols, with PANDAS treatment specifically targeting the strep-related immune response.