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When PANDAS Escape the Zoo for Your Brain

By Olivia Baccellieri

Strep throat - an illness so ubiquitous, most people have been diagnosed with it, or know someone who has suffered through its unpleasant raspiness. The symptoms and side effects are thought to be well-known, but the last twenty years in medical research presents otherwise. In 1998, researchers Swedo et al. identified PANDAS - pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections. Cases of children presenting with streptococcal infections began to puzzle doctors. In the months following their initial diagnosis, long after their symptoms of strep throat had ceased, some children presented with new, and seemingly unrelated symptoms. Their new diagnosis? Obsessive-compulsive disorder (OCD).

Leon et al. (2017) investigated this puzzling association between streptococcal infections and OCD. PANDAS is largely defined by the presence of OCD and/or a tic disorder, pre-pubertal onset, acute onset and has a relapsing–remitting symptom course. Tic disorders, with the most commonly known example being Tourette’s Syndrome, occur when a person experiences uncontrollable physical or verbal expressions. Group A beta-hemolytic streptococcal (GAS) related infections, alongside an association with neurological abnormalities, are also present in PANDAS. Specifying the early onset of this particular presentation of OCD is important, as approximately 0.1–3.6% of the general population experience pediatric-onset OCD. Examining the cases of thirty-three children, Leon et al. sought to identify potential treatments for PANDAS, and other disorders that simultaneously afflicted these study participants.

Upon a clinical intake, Leon et al. found that 18% of the 33 children in their study were also diagnosed with attention-deficit hyperactivity disorder (ADHD), 15% were diagnosed with an anxiety disorder, and 9% were diagnosed with a chronic tic disorder or OCD. Identifying these comorbid conditions is important, as this awareness may influence the chosen course of treatment. Leon et al. hypothesized that providing these children with a dose of antibiotics - particularly, penicilin - would decrease the severity of their OCD symptoms. Eight of these thirty-three children engaged in cognitive behavioral therapy (CBT), which specifically utilized exposure and response prevention therapy. CBT can provide those with OCD the agency to reduce their tendencies to engage in obsessive thinking or from acting on their compulsive behaviors.

At the conclusion of this longitudinal study, Leon et al. identified 25 participants who expressed improvement in their OCD symptoms. 21 of the 33 children described their overall functioning as “very good” during the preceding six-month period. However, 24 of the 33 children reported experiencing a total of 59 OCD-symptom flare-ups during the four-year study. 61% of these flare-ups were treated with antibiotics, and non-steroidal anti-inflammatory drugs were used to treat 30% of these episodes. Additionally, Leon et al. concluded that 88% of their study’s participants were in near or complete remission of PANDAS during the follow-up phase of their research. This is a highly significant finding, as this suggests that PANDAS may have a shorter lifespan than other pediatric OCD cases.

The rarity of PANDAS presents a variety of challenges for patients, families, and clinicians. This disorder can be particularly overwhelming for both a child and their caregivers due to OCD being such an unforeseen aftermath of having strep throat. Clinicians should be aware of the possibility of a child developing PANDAS following a bout of strep throat - otherwise, if a child presents with OCD symptoms seemingly out of the blue, a lack of knowledge could negatively impact their course of treatment. Commencing studies for this disorder, and for other uncommon mental health conditions, is vital for developing greater understanding toward these issues. Additionally, more knowledge regarding these disorders will contribute to effective treatment methods and delivery. The sudden onset nature of PANDAS can be deeply unsettling and disturbing, and increasing awareness within the healthcare community can help to ease the worry of patients and their families.


Leon, J., Homer, R., Grant, P., Farmer, C., D'Souza, P., Kessler, R., … Swedo, S. (2018). Longitudinal outcomes of children with pediatric autoimmune neuropsychiatric disorder associated with streptococcal infections (PANDAS). European Child Adolescent Psychiatry, 27, 637–643.

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