PANDAS

Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) is a controversial hypothetical diagnosis for a subset of children with rapid onset of obsessive–compulsive disorder (OCD) or tic disorders coming immediately after a Streptococcus infection. Symptoms are proposed to be caused by group A streptococcal (GAS), and more specifically, group A beta-hemolytic streptococcal (GABHS) infections. OCD and tic disorders are hypothesized to arise in a subset of children as a result of a post-streptococcal autoimmune process. The proposed link between infection and these disorders is that an autoimmune reaction to infection produces antibodies that interfere with basal ganglia function, causing symptom exacerbations, and this autoimmune response results in a broad range of neuropsychiatric symptoms.

The PANDAS hypothesis, first described in 1998, was based on observations in clinical case studies by Susan Swedo et al. at the US National Institute of Mental Health and in subsequent clinical trials where children appeared to have dramatic and sudden OCD exacerbations and tic disorders following infections. Whether PANDAS was a distinct entity differing from other cases of tic disorders or OCD is debated. As the PANDAS hypothesis was unconfirmed and unsupported by data, a new definition was proposed by Swedo and colleagues in 2012. In addition to the 2012 broader pediatric acute-onset neuropsychiatric syndrome (PANS), two other categories have been proposed: childhood acute neuropsychiatric symptoms (CANS) and pediatric infection-triggered autoimmune neuropsychiatric disorders (PITAND). The CANS/PANS hypotheses include different possible mechanisms underlying acute-onset neuropsychiatric conditions, but do not exclude GAS infections as a cause in a subset of individuals. PANDAS, PANS and CANS are the focus of clinical and laboratory research but remain unproven.