The prevalence of tics in special education (SpEd) students and in a matched control sample of students in regular classroom programs (RegEd) was determined in a large-scale, community-based epidemiological study at the University of Rochester School of Medicine, NY. A total of 1596 students (ages 8.5-17.5 yrs) drawn from the Rochester City School district and 9 surrounding Monroe County suburban public school districts were interviewed from November 1994 to March 1998. Three RegEd subjects were randomly selected for every one SpEd subject. The disability classifications of SpEd students included learning disability (79%), speech impaired (14%), emotionally disturbed (5%), and other (2%). Interviews of 341 SpEd and 1255 RegEd students were conducted by neuropsychological technicians trained to assess the presence and severity of tics, and to distinguish them from other movements and behaviors. Each technician had spent 3 months with a neurologist, expert in movement disorders, observing approximately 75 children with tics prior to the study. Parent interviews were conducted in the school office or by telephone. RegEd and SpEd students were evaluated in the same time periods, and interviewers were blinded to educational placement. Tics were classified as either definite (observed) or probable (based on historical information), and motor or vocal. The proportion of tics in the SpEd and RegEd groups was 27% and 19.7%, respectively (p=.008). The weighted prevalence estimates for tics were 23.4% for SpEd and 18.5% for RegEd students. Including only definite tics, the SpEd group still had a higher proportion of tics (p=.09). A higher percentage of students in SpEd (7%) met diagnostic criteria for Tourette syndrome than those in RegEd (3.8%;p=.01). Thirty percent of students in the SpEd group were receiving stimulant medication compared to 7.5% of RegEd students. Tics are a common disorder in school children and are strongly azssociated with school dysfunction and placement in special education. 
COMMENT. This represents a further publication in a long series of studies of tic disorders and Tourette syndrome conducted at the University of Rochester and involving school children in Monroe County. The observed prevalence of tics among children attending regular classes in the present study (18.5%) is higher than that previously quoted in the literature (4 to 16%), but the prevalence (27%) among children in special education is similar (26%) to a study cited by Robertson MM . Comparing a group of 35 children in special education with 35 in regular classes, the incidence of tics was 26% and 6%, respectively. Although the authors of the Rochester study state that only a small number of subjects took medication on the day of the interview, it is noteworthy that 30% of SpEd students were under treatment with stimulant medication and presumably were diagnosed with ADHD. Despite recent studies that minimize an association (Ped Neur Briefs Aug 1999;13:57-58) , our experience and earlier studies have shown that stimulant therapy for ADHD may precipitate tics in susceptible children, and the effect is dose-related [4, 5]. Furthermore, tics and Tourette syndrome received no or only passing mention in neurological literature and textbooks until the use of stimulants became popular in the 1960s . It is prudent to monitor for tics during treatment of ADHD with stimulants.