O bsessive-compulsive disorder is a common disorder, with a lifetime prevalence in adolescence of 2%-3% (1, 2). The rising frequency of diagnosis of obsessive-compulsive disorder over the last decade (3) has motivated researchers to distinguish subtypes of obsessive-compulsive disorder. Several studies (4-6 and unpublished study by V. Eapen et al.) have compared adult patients with obsessive-compulsive disorder with and without chronic tic disorder or Gilles de la Tourette's disorder on the content of their obsessions and compulsions. The subjects were patients ascertained through clinical facilities, and the study groups may therefore have been biased toward greater severity and comorbidity. In addition, the patients were adults and might have been further along in the natural course of obsessive-compulsive disorder than would be younger patients. Thus, the differences found between the two manifestations of obsessive-compulsive disorder, with and without tics or Tourette's disorder, may not provide profiles for the full range of obsessive-compulsive disorder.The present study focused on an epidemiological sample of unreferred adolescents diagnosed with obsessive-compulsive disorder. The analyses were directed at distinguishing qualitatively between obsessive-compulsive disorder with and without tics.
METHODThe sample included 861 adolescents 17 years old, 436 boys and 425 girls. The screening was part of the physical examination that precedes induction into the Israel Defence Force. The induction centers screen over 95% of a complete cohort, and the present sample comprised consecutively sampled adolescents. The diagnostic interview used was the Yale Schedule for Tourette Syndrome and Other Behavioral Disorders, Hebrew Version (7). The adolescents were first interviewed by child psychiatrists using abridged modules from this schedule, which includes an extended Tourette's disorder module and an obsessive-compulsive disorder module with the 58-item YaleBrown Obsessive Compulsive Scale (8). They were screened for anxiety disorders, Tourette's disorder, and tics. Subsequently, 100 subjects who received a preliminary diagnosis of anxiety disorder, Tourette's disorder, or tics were invited for a full diagnostic interview using the unabridged Yale Schedule for Tourette Syndrome and Other Behavioral Disorders, Hebrew Version, administered by a child psychiatrist.Fifty comparison subjects, whose interviews indicated the absence of these disorders in the initial assessment, were randomly interspersed to reduce expectation bias in the second-level interviewer. For this second phase, 144 individuals were seen: 94 subjects with a preliminary diagnosis of anxiety disorder, Tourette's disorder, or tics and 50 comparison subjects. Written informed consent was obtained from the 144 individuals after the aims, procedure, and implications