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.”[4]

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.[5]