Streptococcal upper respiratory tract infections and psychosocial stress predict future tic and obsessive-compulsive symptom severity in children and adolescents with Tourette syndrome and obsessive-compulsive disorder.

BACKGROUND: One goal of this prospective longitudinal study was to identify new group A beta-hemolytic streptococcal infections (GABHS) in children and adolescents with Tourette syndrome (TS) and/or obsessive-compulsive disorder (OCD) compared with healthy control subjects. We then examined the power of GABHS infections and measures of psychosocial stress to predict future tic, obsessive-compulsive (OC), and depressive symptom severity.
METHODS: Consecutive ratings of tic, OC, and depressive symptom severity were obtained for 45 cases and 41 matched control subjects over a 2-year period. Clinical raters were blinded to the results of laboratory tests. Laboratory personnel were blinded to case or control status and clinical ratings. Structural equation modeling for unbalanced repeated measures was used to assess the sequence of new GABHS infections and psychosocial stress and their impact on future symptom severity.
RESULTS: Increases in tic and OC symptom severity did not occur after every new GABHS infection. However, the structural equation model found that these newly diagnosed infections were predictive of modest increases in future tic and OC symptom severity but did not predict future depressive symptom severity. In addition, the inclusion of new infections in the model greatly enhanced, by a factor of three, the power of psychosocial stress in predicting future tic and OC symptom severity.
CONCLUSIONS: Our data suggest that a minority of children with TS and early-onset OCD were sensitive to antecedent GABHS infections. These infections also enhanced the predictive power of current psychosocial stress on future tic and OC symptom severity. Copyright 2010 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.