Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections or PANDAS is an autoimmune response related to a streptococcal infection. The condition is characterized by the sudden and unexpected onset of a tic disorder or obsessive compulsive disorder (OCD) or both. It can be accompanied by neuropsychiatric symptoms such as aggressive behaviour and handwriting changes.

A US research team first identified PANDAS in 1994 while studying patients with Sydenham Chorea, a neurological disorder related to rheumatic fever (strep infection) characterized by involuntary muscular movements: 

Several converging lines of evidence suggest that some behavioral and neurological abnormalities of childhood may be mediated through antineuronal antibodies.These antineuronal antibodies appear to arise in response to group A [beta]-hemolytic streptococcal (GABHS) infections and to cross-react with cells within the central nervous system (CNS).

As many as 75% of school aged children develop strep throat infections every year and are treated effectively with antibiotics. However, according to the PANDAS Network, 1 in 200 children may go on to develop PANDAS. Significantly, while 81% of these cases are linked to strep infection especially Streptococcus pyogenes (group A strep) 19% reported infections of mycoplasma, B. burgdorfer (Lyme), herpes simplex, and other pathogens. Twice as many boys as girls develop PANDAS. 

Anti-basal ganglia antibodies may explain the symptoms of PANDAS. A 2020 study in Frontiers of Psychiatry explains: “The molecular mimicry hypothesis postulates that symptoms arise when antibodies against the dominant streptococcal group A carbohydrate epitope, N-acetyl-beta D-glucosamine (GLcNAc), cross-react with neurons in human basal ganglia.”

Further research indicates that these autoantibodies target D1 and D2 dopamine receptors which can trigger the release of excess dopamine thereby contributing to tics and other symptoms of PANDAS.