Abstract
Population-based assessment of Tourette syndrome (TS) and other tic disorders produces a paradox. On one hand, ideally diagnosis of tic disorders requires expert observation. In fact, diagnostic criteria for TS explicitly require expert assessment of tics for a definite diagnosis. On the other hand, large-scale population surveys with expert assessment of every subject are impracticable. True, several published studies have successfully used expert assessment to find tic prevalence in a representative population (e.g. all students in a school district). However, extending these studies to larger populations is daunting. We created a multimedia tool to demonstrate tics to a lay audience, discuss their defining and common attributes, and address features that differentiate tics from other movements and vocalizations. A first version was modified to improve clarity and to include a more diverse group in terms of age and ethnicity. The result is a tool intended for epidemiological research. It may also provide additional benefits, such as more representative minority recruitment for other TS studies and increased community awareness of TS.
Highlights
Some important questions in Tourette Syndrome (TS) require large-scale epidemiological studies
VISIT-TS was designed to improve sensitivity by making sure subjects and parents have seen typical tics on video before answering questions about them. This approach is based on the premise that survey respondents will respond more accurately about tics in themselves after the interviewer shows them a brief video about tics than they would if only asked about history by questionnaire or by cross-sectional lay observation
Some data are available to judge the sensitivity of lay diagnostic instruments for tic disorders
Summary
Some important questions in Tourette Syndrome (TS) require large-scale epidemiological studies. The results may differ so dramatically because of true genetic or epigenetic differences between racial groups (Robertson et al, 2009), or because social determinants of health care create barriers to diagnosis or treatment that create an artifactual difference in apparent prevalence (American Psychiatric Association, 2013, under Tic Disorders/Culture-Related Diagnostic Issues; CDC, 2009; Olfson et al, 2011). Settling this question will require large-scale prevalence studies that recruit an adequate, representative sample of minority populations. There can be difficulties in conveying adequate descriptions of movements by words alone; probable miscategorization or failure to recognize some abnormal movements by both subjects and lay interviewers; the broad differential diagnosis of tics, including other movement disorders and normal movements; and misinterpretation of typical tics due to their intermittent nature, suppressibility and fluctuating severity over time or in response to the environment
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