The prevalence of tic disorders and clinical characteristics in children

Abstract

Background Prevalence is a simple statement about the frequency of a disease in the population. For many medical conditions, including Tourette syndrome, there are true cases that have not been previously diagnosed due to problems of access to appropriate clinical services. Therefore, to obtain a trustworthy estimate of prevalence, it is necessary to go beyond cases identified in clinical settings and evaluate community samples. Method We reviewed 11 community surveys in children with Tourette syndrome (TS) published since 2000. We also examined the frequency of co-occurring psychiatric conditions in community samples and large clinically-ascertained samples. Results Transient tics are relatively common affecting as many as 20% of school-age children. The 11 studies reviewed here offer a wide range of estimates from 2.6 to 38 per 1000 children for TS. Six studies provide estimates in a narrower range from 4.3 to 7.6 per 1000, but the confidence interval around this narrower range remains wide. Six studies provided results on chronic tic disorders ranging from 3 to 50 per 1000 for Chronic Motor Tic Disorder and 2.5 to 9.4 per 1000 for Chronic Vocal Tic Disorder. Community samples and large clinically-ascertained samples consistently show high rates of ADHD, disruptive behavior and anxiety disorders in children with TS. Conclusions The wide range of prevalence estimates for TS and chronic tic disorders is likely due to differences in sample size and assessment methods. The best estimate of prevalence for TS in school-age children is likely to fall between 4 and 8 cases per 1000. Clinical assessment of children with chronic tic disorders warrants examination of other problems such as ADHD, disruptive behavior and anxiety.

VISIT-TS: A multimedia tool for population studies on tic disorders

“…Supporting the potential importance of this concern, epidemiological studies that included expert examination ( Comings et al , 1990; Cubo et al , 2011; Hornsey et al , 2001; Jin et al , 2005; Khalifa & von Knorring, 2003; Khalifa & von Knorring, 2005; Kurlan et al , 1994; Lanzi et al , 2004; Mason et al , 1998; Wang & Kuo, 2003) generally report a several-fold higher prevalence of tic disorders than do other epidemiological studies ( CDC, 2009; Scahill et al , 2014). …”

A one year follow up study of persistent motor tic disorder treated with risperidone in a children’s hospital in Sri Lanka

“…In a review of community surveys, 20% of school children were detected to have transient tics 2 . Many of these transient tics are time limited and may not require specific treatment.…”

Progress in research on Tourette syndrome

“…Dr. Larry Scahill presented data from the CDC epidemiological study mentioned above; 1 for this issue, he and his colleagues summarize recent studies on the prevalence of TS. 19 Dr. John Walkup reported on information on “real-life” TS treatment from two large samples, one from Medicaid and one from private insurers. 8 The results suggest that many children with tics do not get medical attention, and that those who do present to clinicians have substantial comorbidity.…”