[PANDAS: a possible model for adult OCD pathogenesis]

Obsessive-compulsive disorder is a disabling disorder. Genetic predisposing factors may have an important role in the onset of the symptoms, but is not been individualized any specific gene yet. In the last years it has been demonstrated that obsessive-compulsive disease and/or tic syndromes may be triggered by an antecedent infection especially with group A beta-hemolytic streptococci. On the basis of recent studies has been postulated that in genetically predisposed individuals, certain streptococcal antigens trigger antibodies which, through a process of molecular mimicry, cross-react with epitopes on the basal ganglia. According to such hypothesis, the acronym PANDAS has been used to describe a subset of children with abrupt onset or exacerbations of OCD or tics, or both, following streptococcal infections. Neuroimaging studies reveal increased basal ganglia volumes, and the proposed cause involves the cross-reaction of streptococcal antibodies with basal ganglia tissue. The hypothesis of a possible involvement of the immunitary system seems justified from quantitative alterations of TNF-alpha, IL-6 and IL-1 in the patients' serum with such syndrome. Echotomographic studies on cardiac valves have not yet demonstrated the parallels between PANDAS and Sydenham's chorea. The use of treatment strategies, such as therapeutic plasmapheresis or intravenous immunoglobulin, has been proposed to explain the autoimmune process responsible for the pathogenesis of PANDAS. Further research is still necessary in order to understand the role of streptococcal infection in the pathogenesis of PANDAS.