Reader Response: Association of Group A Streptococcus Exposure and Exacerbations of Chronic Tic Disorders: A Multinational Prospective Cohort Study.

Abstract

The European Immuno-Neuropsychiatric Association Scientific and Medical Advisory Group welcomes this study that considered associations between exposure to group A streptococcus (GAS) and chronic tic disorders.1 This well-conducted study, with a balanced discussion, found no significant association between GAS and exacerbation of tics in children with chronic tic disorders. It is important that the study population was composed mainly of patients with a previous diagnosis of Tourette syndrome (90.8%). Thus, it is likely that the vast majority did not meet the diagnostic criteria for immune-mediated conditions, such as pediatric acute-onset neuropsychiatric syndrome/pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANS/PANDAS), which is differentiated from Tourette syndrome by presenting with an acute onset of several neuropsychiatric symptoms that may include tics or movement disorders. The results and conclusions should not therefore be used to refute the existence of immune-mediated conditions, including PANS/PANDAS, or to imply that these conditions do not similarly have an association with GAS infection. It is also interesting that an association between exacerbation of attention-deficit/hyperactivity disorder symptoms and GAS exposure was found, which we agree should be further investigated. The value of looking for GAS immune-mediated changes in the context of acute-onset tic disorders is not delineated by this study, and we feel that point should be highlighted.