Prevalence and clinical correlates of tic disorders in a community sample of school-age children

To examine the prevalence, clinical characteristics and course of children with tics identified in a community sample. This
was a three-stage study. At the age of 9 to 11, parents of 8,244 children born at Aarhus University Hospital Skejby between
January 1990 and April 1992 were invited to complete a screening questionnaire about tics. One year later participating parents
completed the Strengths and Difficulties Questionnaire (SDQ). From December 2004 to June 2005, when the cohort was 13–15 years
of age, parents of the children who screened positive for tics were interviewed in detail about tic disorders. The prevalence
of Tourette Syndrome (TS) was 0.6 and 0.6% of chronic motor tics (CMT). Approximately one-third of those with a chronic tic
disorder [CTD (TS and CMT)] reported remission of tics by age 13–15. On the parent-rated SDQ children with a CTD were five
times more likely (OR = 5.0, 95% CI = 2.6–9.2) to fall into the clinical range of hyperactivity, twice as likely (OR = 2.2,
95% CI = 2.1–7.5) to exhibit disruptive and defiant behavior and over four times more likely to have emotional difficulties
(OR = 4.7, 95% CI = 2.5–8.6) compared to children without tic disorders. Children with hyperactivity and CTD were more impaired
than subjects with CTD only. Children with CTD and hyperactivity show greater symptom severity across several domains of behavior
and overall impairment. In the absence of hyperactivity, children with CTD are at increased risk for emotional difficulties,
but not disruptive behavior problems.