OCD and tic disorders are hypothesized to arise in a subset of children as a result of a post-streptococcal autoimmune process. The PANDAS hypothesis is unconfirmed and unsupported by data, and two new categories have been proposed: PANS (pediatric acute-onset neuropsychiatric syndrome) and CANS (childhood acute neuropsychiatric syndrome). The CANS/PANS hypotheses include different possible mechanisms underlying acute-onset neuropsychiatric conditions, but do not exclude GABHS infections as a cause in a subset of individuals. PANDAS, PANS and CANS are the focus of clinical and laboratory research but remain unproven. Whether PANDAS is a distinct entity differing from other cases of tic disorders or OCD is debated. PANDAS is a subset of the pediatric autoimmune neuropsychiatric syndrome (PANS) hypothesis.