Tourette's syndrome, chronic tics, and comorbid attention deficit/hyperactivity disorder in elementary students.

BACKGROUND This study estimated the true prevalence of chronic motor and vocal tic disorders, and Tourette's syndrome in students as well as its comorbidity with attention deficit/hyperactivity disorder (ADHD). METHODS A random clustered sample of elementary students was selected from schools in Tabriz, Iran. Students were screened by Conner's teacher rating scale for ADHD and a detailed history from parents and teachers for the presence of any type of tic was obtained. Next, a clinical interview based on the Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL), and an interview with parents lead to the definitive diagnosis. RESULTS A total of 1658 children were evaluated. Vocal tic was observed in 3.2% (±SD = 0.02) students, and was more prevalent in boys. ADHD was diagnosed in 45.5% of these students. Motor tic was observed in 7.3% (±SD = 0.02) of students. Almost half (48.1%) of these students had ADHD. Tourette's syndrome was observed in 1.3% (±SD = 0.01), with a male/female ratio of 3.5:1. CONCLUSION This is the first study to provide the prevalence of chronic tics in elementary school students in Iran. ADHD is more common among students with chronic tics and Tourette's syndrome.