Infections and Tic Disorders

Abstract Several associations between patients with infections, particularly group A streptococcal (GAS) infections, and subsequent tics and obsessive–compulsive symptoms have been established in population-based studies, suggesting at least a nonspecific role of infections in a subgroup of patients with tics. Expanding the clinical entity of pediatric autoimmune neuropsychiatric disorders associated with streptococcus, a broader spectrum named pediatric acute-onset neuropsychiatric syndromes (PANS) has been proposed, which encompasses phenotypes dominated by obsessive–compulsive symptoms or eating behavior abnormalities and includes tics as accompanying features. PANS are defined by the temporal course but are not limited to post-infectious etiologies. In chronic tic disorders, GAS infections do not seem to be a major determinant of tic exacerbations, although a potential interactive effect with psychosocial stress cannot be excluded. The role of other pathogens in influencing course and onset of tic disorders remains uncertain. The complex interaction of patient-specific attributes (neurochemical and immune vulnerability genes leading to maladaptive neuropsychiatric or immune function) with environmental attributes (psychosocial stress, injuries, substance exposures, and pathogen-specific properties) creates an interesting and ongoing research challenge.