Tourette's syndrome and 'PANDAS': will the relation bear out? Pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection.

Despite strong evidence of the importance of hereditary factors in the etiology of Tourette's syndrome (TS), research findings have consistently pointed to a role of environmental influences. A recent line of research has suggested that tic disorders and associated behavioral disturbances, such as obsessive-compulsive disorder, might develop following streptococcal infection by the process of molecular mimicry, whereby antibodies directed against bacterial antigens cross-react with brain targets. Such investigations have given rise to the notion that there is a spectrum of childhood neurobehavioral disorders (termed pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection [PANDAS]) that arise by postinfectious autoimmune mechanisms. This article reviews research results supporting the concept of PANDAS and discusses their limitations. Well-designed and adequately controlled studies are needed to determine whether there is a true etiologic relation between streptococcal infection and the onset or exacerbation of childhood neuropsychiatric disorders and whether the use of immune-modifying therapies for these conditions is rational.