PANDAS is an acronym for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. This term describes a hypothesis that there exists a subset of children with rapid onset of obsessive-compulsive disorder (OCD) and/or tic disorders and these symptoms are caused by group A beta-hemolytic streptococcal (GABHS) infections. The proposed link between infection and these disorders is that an initial autoimmune reaction to a GABHS infection produces antibodies that continues to interfere with basal ganglia function, causing symptom exacerbations.
The PANDAS hypothesis was based on observations in clinical case studies at the US National Institute of Health and in subsequent clinical trials where children appeared to have dramatic and sudden OCD exacerbations and tic disorders following infections. There is supportive evidence for the link between streptococcus infection and onset in some cases of OCD and tics, but proof of causality has remained elusive. The PANDAS hypothesis is controversial; whether it is a distinct entity differing from other cases of Tourette syndrome (TS)/OCD is debated.
PANDAS has not been validated as a disease entity; it is not listed as a diagnosis by the International Statistical Classification of Diseases and Related Health Problems (ICD) or the Diagnostic and Statistical Manual of Mental Disorders (DSM). Pediatric acute-onset neuropsychiatric syndrome (PANS) is a 2012 proposal describing another subset of acute-onset OCD cases including "not only disorders potentially associated with a preceding infection, but also acute-onset neuropsychiatric disorders without an apparent environmental precipitant or immune dysfunction".