Distinguishing illness severity from tic severity in children and adolescents with Tourette's disorder.

Objective: To examine whether tic severity, comorbid disorders, or both are associated with illness morbidity in youths with Tourette's disorder (TD).
Method: Subjects were 156 consecutively referred youths (aged 5-20 years) who met DSM-III-R criteria for Tourette's disorder at a major academic medical center. All subjects were evaluated with a clinical interview by a child and adolescent psychiatrist and an assessment battery that included the Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiologic version. Statistical analysis used chi 2 and multivariate logistic regression.
Results: Nineteen (12%) of the 156 youths with TD required psychiatric hospitalization. Current age, TD severity, TD duration, obsessive-compulsive disorder, psychosis, major depression, bipolar disorder, panic disorder, and overanxious disorder were significant univariate predictors of psychiatric hospitalization (p < .01). While tic severity was marginally significant as a predictor of psychiatric hospitalization (p < .05), major depression (p < .016) and bipolar disorder (p < .001) were robust predictors of psychiatric hospitalization, even after statistical adjustment for collinearity and correction for all other variables assessed.
Conclusion: The findings indicate that comorbid mood disorders are strongly associated with illness morbidity in youths with TD, highlighting the importance of attention to comorbidity in patients with TD.