The prevalence and epidemiology of Gilles de la Tourette syndrome. Part 2: tentative explanations for differing prevalence figures in GTS, including the possible effects of psychopathology, aetiology, cultural differences, and differing phenotypes.
ABSTRACT As has been demonstrated, Gilles de la Tourette Syndrome (GTS) occurs in at least 1% of the population worldwide. However, earlier studies suggested a lower prevalence. In addition, the prevalence figures for different studies very between 0.4% and 3.8%. Moreover, the prevalence appears to vary in some parts of the world and races, with a lower rate in Afro-Americans and sub-Saharan black Africans. In this the second part of the review, possible reasons for the differences in prevalence and epidemiology are discussed. Tentative explanations for differing prevalence figures in GTS include problems with the diagnosis of GTS, the multidimensional nature of tics, as well as other tic factors including the waxing and waning of symptoms and the suppressibility of symptoms. Other factors inherent to GTS include the fact that there is no diagnostic test and indeed no definitive diagnosis other than clinical, the fact that psychosocial stresses can lead to increased tic severity, and that comorbid disorders may mask tics. The varying methods of study employed can also effect prevalence. There may be some regional differences in GTS as well, which may be due to a lack of awareness of GTS, or it may be a true reflection of low prevalence as in some populations GTS does appear rare. With regard to the sub-Saharan Africa data and possibly the African American data, matters are much more complex than meets the eye. The following reasons are all possible for the apparent rarity in these populations and include (i) other medical priorities and less propensity to seek health care, (ii) lack of awareness of GTS, (iii) chance, (iv) ethnic and epigenetic differences and reasons, (v) genetic and allelic differences in different races, and (vi) an admixture of races. The aetiology of GTS is also complex, with influences from complex genetic mechanisms, pre- and perinatal difficulties and, in a subgroup, some infections, possibly by epigenetic mechanisms. These may well affect phenotype and, thus, prevalence. There have even been suggestions that people with GTS are increasing. Recent data suggests that GTS is not a unitary condition and that there may well be different types of GTS. The prevalence of GTS in these individual subtypes is unknown. It is suggested that a new nomenclature be adopted for GTS in future, pending further genetic and phenomenological studies. To what extent the aetiology affects the phenotype and, thus, the prevalence is still unclear.
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ABSTRACT: Tourette syndrome is a neurological condition involving involuntary movements and sounds (tics) and is thought to affect as many as 1% of school-aged children. Some young people with Tourette syndrome experience educational difficulties and social difficulties. Current clinical guidelines suggest educators can play an important role in maximising learning potential and reducing the negative impact of this condition on students' social adjustment. Secondary school staff (N = 63) with responsibilities for special educational needs or disabilities completed a survey about support strategies for students with Tourette syndrome. Participants were first asked to suggest potentially helpful strategies and then rated how easily 17 recommended strategies could be implemented in school. The survey participants suggested a range of support strategies that were categorised as (1) promoting knowledge and understanding in school, (2) helping the student to cope with his/her tics, (3) supporting the student's learning and (4) providing social and emotional support. All the recommended support strategies were rated as being easy to implement (or already in place) by the majority of respondents (e.g., increasing staff awareness and regular communication with home). The strategies that were identified as being least easy to implement were those requiring extra staff input (support from teaching assistants and individual/small group working). Additional challenges to providing support were also identified by the participants (e.g., getting input from outside agencies).Journal of Research in Special Educational Needs 10/2014; DOI:10.1111/1471-3802.12077 · 0.53 Impact Factor
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ABSTRACT: Data on medical treatment of children and adolescents with tic disorders are scarce. This study examined the administrative prevalence of psychopharmacological prescriptions in this patient group in Germany. Data of the largest German health insurance fund were analysed. In outpatients aged 0-19 years with diagnosed tic disorder, psychotropic prescriptions were evaluated for the years 2006 and 2011. In 2011, the percentage of psychotropic prescriptions was slightly higher than in 2006 (21.2 vs. 18.6 %). The highest prescription prevalence was found in Tourette syndrome (51.5 and 53.0 %, respectively). ADHD drugs were most frequently prescribed, followed by antipsychotics. In 2011, prescriptions of second generation antipsychotics (SGA) were higher and prescriptions of first generation antipsychotics (FGA) lower than in 2006. Concerning prescribed antipsychotic substances, in 2011 risperidone prescriptions were higher and tiapride prescriptions lower. Paediatricians issued 37.4 %, and child and adolescent psychiatrists issued 37.1 % of psychotropic prescriptions. The FGA/SGA ratio was highest in GPs (1.25) and lowest in child and adolescent psychiatrists (0.96). From 2006 to 2011, there was only a slight increase in psychotropic prescriptions for children and adolescents with a diagnosis of tic disorder in Germany, which stands in contrast towards the significant increase in psychotropic prescriptions in other child and adolescent psychiatric disorders (e.g. ADHD). There were marked differences in treatment patterns by tic disorder subgroups, with Tourette syndrome patients receiving most frequently psychopharmacotherapy. Risperidone prescriptions increased, probably reflecting a switch in prescribing practice towards up-to-date treatment guidelines. In primary care physicians, dissemination of current tic disorder treatment guidelines might constitute an important educational goal.European Child & Adolescent Psychiatry 06/2014; 24(2). DOI:10.1007/s00787-014-0563-6 · 3.55 Impact Factor
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ABSTRACT: The aim of this study was to refine the population prevalence estimate of Tourette Syndrome (TS) in children and to investigate potential sources of heterogeneity in previously published studies. A systematic review was conducted and all qualifying published studies of TS prevalence were examined. Extracted data were subjected to a random-effects meta-analysis weighted by sample size; meta-regressions were performed to examine covariates that have previously been proposed as potential sources of heterogeneity. Twenty-six articles met study inclusion criteria. Studies derived from clinically referred cases had prevalence estimates that were significantly lower than those derived from population-based samples (P = 0.004). Among the 21 population-based prevalence studies, the pooled TS population prevalence estimate was 0.52% (95% confidence interval CI: 0.32-0.85). In univariable meta-regression analysis, study sample size (P = 0.002) and study date (P = 0.03) were significant predictors of TS prevalence. In the final multivariable model including sample size, study date, age, and diagnostic criteria, only sample size (P < 0.001) and diagnostic criteria (omnibus P = 0.003; Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision [DSM-IV-TR]: P = 0.005) were independently associated with variation in TS population prevalence across studies. This study refines the population prevalence estimate of TS in children to be 0.3% to 0.9%. Study sample size, which is likely a proxy for case assessment method, and the use of DSM-IV-TR diagnostic criteria are the major sources of heterogeneity across studies. The true TS population prevalence rate is likely at the higher end of these estimates, given the methodological limitations of most studies. Further studies in large, well-characterized samples will be helpful to determine the burden of disease in the general population. © 2014 International Parkinson and Movement Disorder SocietyMovement Disorders 11/2014; 30(2). DOI:10.1002/mds.26089 · 5.63 Impact Factor