A prevalence study of Gilles de la Tourette syndrome in North Dakota school-age children

Systematic Review and Meta-Analysis of Tourette Syndrome Prevalence; 1986 to 2022

BACKGROUND

Tourette syndrome (TS) is a disorder characterized by a history of multiple motor tics and the emergence of at least one vocal tic during a period of the disorder. The current investigation sought to clarify the prevalence statistics for TS using a systematic review and meta-analysis.

METHODS

This systematic review and meta-analysis covered the period between 1986 and 2022. Embase, Scopus, PubMed, Web of Science, and Google Scholar were searched to locate articles pertinent to the study topic. The I² index was used to examine the heterogeneity of the studies, and a comprehensive meta-analysis was employed to analyze the data.

RESULTS

Ultimately, 30 studies (39 outcomes) were included in the meta-analysis and systematic review. The results showed the global prevalence of TS to be 0.5% (95% confidence interval [CI], 0.3% to 0.8%), with the highest rate of spread observed in the Americas at 0.6% (95% CI, 0.2% to 1.6 %). Analyzing the subgroups of the sample revealed that the highest prevalence was associated with the population of children and adolescents at 0.7% (95% CI, 0.4% to 1.4%) and males at 0.5% (95% CI, 0.2% to 1.0%).

CONCLUSIONS

This comprehensive review and meta-analysis revealed that the prevalence of TS worldwide is sufficiently high, such that attention of medical specialists and health policy makers is warranted.

A 2-year longitudinal follow-up of quantitative assessment neck tics in Tourette's syndrome

Background

Neck motor tics in Tourette’s syndrome can cause severe neck complications. Although addressed in a few longitudinal studies, the clinical course of Tourette’s syndrome has not been quantitatively assessed. We had previously developed a method for quantifying the angular movements of neck tics using a compact gyroscope. Here, we present a follow-up study aimed at elucidating the clinical course of neck tics at both the group and individual levels.

Methods

Eleven patients with Tourette’s syndrome from our previous study participated in the present study, and their neck tics were recorded during a 5-min observation period. The severity of neck symptoms was assessed using the Yale Global Tic Severity Scale. The peak angular velocities and accelerations, tic counts, and severity scores in our previous study (baseline) and the present study (2-year follow-up) were compared at the group and individual levels. The individual level consistency between baseline and follow-up were calculated using intra-class correlation coefficients (ICCs, one-way random, single measure).

Results

At the group level, no significant change was observed between baseline and follow-up. At the individual level, angular velocity (ICC 0.73) and YGTSS scores (ICC 0.75) had substantial consistency over the two time points, and angular acceleration (ICC 0.59) and tic counts (ICC 0.69) had moderate consistency.

Conclusions

The intensity and frequency of neck tics did not change over time. Therefore, quantification of angular neck motor tics will aid in identifying patients with neck tics at high risk for severe neck complications.

The female Tourette patient: Sex differences in Tourette Disorder

Tourette Disorder (TD) is a male predominant neurodevelopmental disorder characterized by tics and frequent psychiatric comorbidities. Girls with TD have later peak symptoms, less remission with age, and worse impairment from tics, particularly in adulthood. Female TD patients are less likely to have Attention Deficit Hyperactivity Disorder and more likely to have anxiety and mood disorders. Hyperandrogenism is associated with TD in both sexes, and neuroanatomic sexual dimorphism is reduced in adult TD patients. Some women report catamenial tics, which may relate to estrogen withdrawal or rises in allopregnanolone. Limited data suggest that several neuroanatomic alterations present in boys with TD are not present in girls with TD. Female sex predicts better response to haloperidol. Further research into female tic pathophysiology may influence sex-specific treatment development.

Influence of Gender on Tourette Syndrome Beyond Adolescence

Although boys are disproportionately affected by tics in Tourette syndrome (TS), this gender bias is attenuated in adulthood and a recent study has suggested that women may experience greater functional interference from tics than men. The authors assessed the gender distribution of adults in a tertiary University-based TS clinic population and the relative influence of gender and other variables on adult tic severity (YGTSS score) and psychosocial functioning (GAF score). We also determined retrospectively the influence of gender on change in global tic severity and overall TS impairment (YGTSS) since adolescence. Females were over-represented in relation to previously published epidemiologic surveys of both TS children and adults. Female gender was associated with a greater likelihood of tic worsening as opposed to tic improvement in adulthood; a greater likelihood of expansion as opposed to contraction of motor tic distribution; and with increased current motor tic severity and tic-related impairment. However, gender explained only a small percentage of the variance of the YGTSS global severity score and none of the variance of the GAF scale score. Psychosocial functioning was influenced most strongly by tic severity but also by a variety of comorbid neuropsychiatric disorders.

The prevalence of diagnosed tourette syndrome in Canada: A national population-based study

OBJECTIVE

The objective of this study was to examine: (1) the prevalence of diagnosed Tourette syndrome in Canada by sex in youth (aged 12-17) and adults and (2) socioeconomic factors in this population.

BACKGROUND

The majority of epidemiological studies of tics have focused on children and youth, with few studies describing the prevalence of tics in adult populations.

METHODS

Canadian data on Tourette syndrome prevalence were derived from the Canadian Community Health Survey 2010 and 2011 cycles, a Statistics Canada population-based cross-sectional survey that collects information related to health status. We determined the prevalence of diagnosed Tourette syndrome and examined sociodemographic factors, including age, sex, education, income, employment, and birthplace.

RESULTS

Overall, 122,884 Canadians participated in the surveys, with 122 participants diagnosed with Tourette syndrome. The prevalence of Tourette syndrome was higher in males in youth: 6.03 per 1000 (95% confidence interval: 3.24-8.81) in males versus 0.48 per 1,000 (95% confidence interval: 0.05-0.91) in females, with a prevalence risk ratio of 5.31 (95% confidence interval: 2.38-11.81). In adults, the prevalence of Tourette syndrome was 0.89 per 1,000 (95% confidence interval: 0.48-1.29) in males versus 0.44 (95% confidence interval: 0.16.0-0.71) in females, with a prevalence risk ratio of 1.93 (95% confidence interval: 1.21-3.08). After adjusting for age and sex, adults with Tourette syndrome had lower odds of receiving postsecondary education or being employed and higher odds of having income lower than the median and receiving governmental support.

CONCLUSION

Data on the prevalence of Tourette syndrome in adults are scarce because most studies focus on children. Our data demonstrate a decreasing prevalence risk ratio for sex in adults compared to children. A diagnosis of Tourette syndrome is associated with lower education, income, and employment in adulthood. © 2016 International Parkinson and Movement Disorder Society.

Population prevalence of Tourette syndrome: a systematic review and meta-analysis

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.

Prevalence of Tourette syndrome and chronic tics in the population-based Avon longitudinal study of parents and children cohort

OBJECTIVE

Recent epidemiologic studies have demonstrated that Tourette syndrome (TS) and chronic tic disorder (CT) are more common than previously recognized. However, few population-based studies have examined the prevalence of co-occurring neuropsychiatric conditions such as obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD). We evaluated the prevalence of TS, CT, and their overlap with OCD and ADHD in the Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort.

METHOD

A total of 6,768 children were evaluated using longitudinal data from mother-completed questionnaires. DSM-IV-TR diagnoses of TS and CT were derived using three levels of diagnostic stringency (Narrow, Intermediate, and Broad). Validity of the case definitions was assessed by comparing gender ratios and rates of co-occurring OCD and ADHD using heterogeneity analyses.

RESULTS

Age 13 prevalence rates for TS (0.3% for Narrow; 0.7% for Intermediate) and CT (0.5% for Narrow; 1.1% for Intermediate) were consistent with rates from other population-based studies. Rates of co-occurring OCD and ADHD were higher in TS and CT Narrow and Intermediate groups compared with controls but lower than has been previously reported. Only 8.2% of TS Intermediate cases had both OCD and ADHD; 69% of TS Intermediate cases did not have either co-occurring OCD or ADHD.

CONCLUSIONS

This study suggests that co-occurring OCD and ADHD is markedly lower in TS cases derived from population-based samples than has been reported in clinically ascertained TS cases. Further examination of the range of co-occurring neuropsychiatric disorders in population-based TS samples may shed new perspective on the underlying shared pathophysiology of these three neurodevelopmental conditions.

Translocation breakpoint at 7q31 associated with tics: further evidence for IMMP2L as a candidate gene for Tourette syndrome

Gilles de la Tourette syndrome is a complex neuropsychiatric disorder with a strong genetic basis. We identified a male patient with Tourette syndrome-like tics and an apparently balanced de novo translocation [46,XY,t(2;7)(p24.2;q31)]. Further analysis using array comparative genomic hybridisation (CGH) revealed a cryptic deletion at 7q31.1-7q31.2. Breakpoints disrupting this region have been reported in one isolated and one familial case of Tourette syndrome. In our case, IMMP2L, a gene coding for a human homologue of the yeast inner mitochondrial membrane peptidase subunit 2, was disrupted by the breakpoint on 7q31.1, with deletion of exons 1-3 of the gene. The IMMP2L gene has previously been proposed as a candidate gene for Tourette syndrome, and our case provides further evidence of its possible role in the pathogenesis. The deleted region (7q31.1-7q31.2) of 7.2 Mb of genomic DNA also encompasses numerous genes, including FOXP2, associated with verbal dyspraxia, and the CFTR gene.

The roles of anxiety and depression in connecting tic severity and functional impairment

The current study examined relationships between tic severity and both functional impairment and perceived quality of life (QOL) in adults with a chronic tic disorder. The authors explored whether these relationships were moderated by anxiety and depressive symptoms. Five-hundred adults with Tourette's Disorder, Chronic Motor Tic Disorder, or Chronic Vocal Tic Disorder participated in a comprehensive self-report internet-based survey. Anxiety and depressive symptoms moderated the relationship between tic severity and functional impairment such that stronger relationships were documented in participants with elevated depressive or anxious symptoms. Limitations and implications for research and clinical practice are discussed.

Enlargement of thalamic nuclei in Tourette syndrome

CONTEXT

The basal ganglia and thalamus together connect in parallel closed-loop circuits with the cortex. Previous imaging studies have shown modifications of the basal ganglia and cortical targets in individuals with Tourette syndrome (TS), but less is known regarding the role of the thalamus in TS pathogenesis.

OBJECTIVE

To study the morphological features of the thalamus in children and adults with TS.

DESIGN

A cross-sectional, case-control study using anatomical magnetic resonance imaging.

SETTING

University research center.

PARTICIPANTS

The 283 participants included 149 with TS and 134 normal control individuals aged 6 to 63 years.

MAIN OUTCOME MEASURES

Conventional volumes and measures of surface morphology of the thalamus.

RESULTS

Analyses of conventional volumes and surface morphology were consistent in demonstrating an enlargement in TS-affected thalami. Overall volumes were 5% larger in the group composed of children and adults with TS. Statistical maps of surface contour demonstrated enlargement over the lateral thalamus. Post hoc testing indicated that differences in IQ, comorbid illnesses, and medication use did not account for these findings.

CONCLUSIONS

Morphological abnormalities in the thalamus, together with the disturbances reported in the sensorimotor cortex, striatum, and globus pallidus, support the hypothesis of a circuitwide disorder within motor pathways in TS. The connectivity and function of the numerous and diverse thalamic nuclei within cortical-subcortical circuits constitute an anatomical crossroad wherein enlargement of motor nuclei may represent activity-dependent hypertrophy within this component of cortical-subcortical motor circuits, or an adaptive response within a larger putative compensatory system that could thereby directly modulate activity in motor circuits to attenuate the severity of tics.

The prevalence and epidemiology of Gilles de la Tourette syndrome. Part 1: the epidemiological and prevalence studies

The prevalence and epidemiology of Gilles de la Tourette syndrome (GTS) are more complex than was once thought. Until fairly recently, GTS was thought to be a rare and, according to some, a psychogenically mediated disorder. Prevalence depends, at least in part, on the definition of GTS, the type of ascertainment, and epidemiological methods used. However, in dedicated specialist GTS clinics, the majority of patients were noted to have positive family histories of tics or GTS, and large, extended, multiply-affected GTS pedigrees indicated that many family members had undiagnosed tics or GTS: it was therefore realized that GTS was far from uncommon. Seven early epidemiological studies reported that GTS was uncommon or rare for a variety of reasons. More recently, however, two pilot studies and 12 large definitive studies in mainstream school and school-age youngsters in the community, using similar multistage methods, have documented remarkably consistent findings, demonstrating prevalence figures for GTS of between 0.4% and 3.8% for youngsters between the ages of 5 and 18 years. Of the 420,312 young people studied internationally, 3,989 (0.949%) were diagnosed as having GTS. It is therefore suggested that a figure of 1% would be appropriate for the overall international GTS prevalence figure. There were however, "outliers" to the figure. For instance, GTS does seem to be substantially rarer in African-American people and has been reported only very rarely in sub-Saharan black African people. GTS is found in all other cultures, although to possibly differing degrees. In all cultures where GTS has been reported, the phenomenology is similar, highlighting the biological underpinnings of the disorder.

Prevalence of tic disorders among schoolchildren in Warsaw, Poland

OBJECTIVE

To estimate the prevalence and to describe clinical characteristics of tic disorders in 12-15 year old Warsaw schoolchildren.

METHOD

Children attending 24 randomly selected schools were screened by inquiring their parents and teachers. Children indicated as tic-positive by the screening procedure were investigated using semi-structured questionnaires and the Polish version of YGTSS scale. A validity study involved random selection and investigation of 130 non-indicated subjects.

RESULTS

Out of 1,579 screened children, 104 met criteria for tic disorders, giving a lifetime prevalence of 9.9% (95% CI 7.1-12.6%) and a point prevalence of 6.7% (4.3-9.1%). Lifetime prevalence of ICD-10 tic disorders was 2.6% (95% CI 1.2-4.1%) for transient tic disorder (TTD); 3.7% (1.9-5.4%) for chronic tic disorder (CTD); 0.6% (0.2-0.9%) for Tourette disorder (TD); and 2.9% (1.2-4.6%) for non-specific tic disorder. Screening procedure had high sensitivity (92%) and low positive predictive value (18%).

CONCLUSION

Tic disorders are common among Warsaw schoolchildren, have mild severity and form a continuum. The present study has confirmed numerous problems with studying neurobehavioral disorders in general population not referred to physicians, and stressed out the need to improve education on tic disorders in the general public.

Morphologic features of the amygdala and hippocampus in children and adults with Tourette syndrome

CONTEXT

Limbic portions of cortical-subcortical circuits are likely involved in the pathogenesis of Tourette syndrome (TS). They are anatomically, developmentally, neurochemically, and functionally related to the basal ganglia, and the basal ganglia are thought to produce the symptoms of tics, obsessive-compulsive disorder, and attention-deficit/hyperactivity disorder that commonly affect persons with TS.

OBJECTIVE

To study the morphologic features of the hippocampus and amygdala in children and adults with TS.

DESIGN

A cross-sectional, case-control study using anatomical magnetic resonance imaging.

SETTING

University research center.

PARTICIPANTS

A total of 282 individuals (154 patients with TS and 128 controls) aged 6 to 63 years.

MAIN OUTCOME MEASURES

Volumes and measures of surface morphologic features of the hippocampus and amygdala.

RESULTS

The overall volumes of the hippocampus and amygdala were significantly larger in the TS group. Surface analyses suggested that the increased volumes in the TS group derived primarily from the head and medial surface of the hippocampus (over the length of the dentate gyrus) and the dorsal and ventral surfaces of the amygdala (over its basolateral and central nuclei). Volumes of these subregions declined with age in the TS group but not in controls, so the subregions were significantly larger in children with TS but significantly smaller in adults with TS than in their control counterparts. In children and adults, volumes in these subregions correlated inversely with the severity of tic, obsessive-compulsive disorder, and attention-deficit/hyperactivity disorder symptoms, suggesting that enlargement of the subregions may have a compensatory and neuromodulatory effect on tic-related symptoms.

CONCLUSION

These findings are consistent with the known plasticity of the dentate gyrus and with findings from previous imaging studies suggesting the presence of failed compensatory plasticity in adults with TS who have not experienced the usual decline in symptoms during adolescence.

Executive functioning in children with autism and Tourette syndrome

The main aims of this study were to investigate if children with high-functioning autism (HFA) and children with Tourette syndrome (TS) can be differentiated in their executive functioning (EF) profile compared to normal controls (NCs) and compared to each other and to investigate whether children with HFA or children with TS and a comorbid group of children with both disorders are distinct conditions in terms of EF, Four groups of children participated in this study: HFA, TS, comorbid HFA + TS, and a NC group. All children were in the age range of 6 to 13 years. The groups were compared on five major domains of EF: inhibition, visual working memory, planning, cognitive flexibility, and verbal fluency. Children with HFA scored lower than NC children on all the EFs measured. Children with TS and NC children showed the same EF profile. The HFA group scored lower than the TS group for inhibition of a prepotent response and cognitive flexibility. Children with HFA performed poorer than children with comorbid HFA + TS on all functions, with the exception of inhibiting an ongoing response, interference control, and verbal fluency. Children with TS and children with comorbid HFA + TS could not be differentiated from one another in terms of EF. This study indicates that EF deficits are highly characteristic of children with HFA in comparison to children with TS and NC. The results suggest that for the comparison between HFA and TS groups, it is important to take into account comorbidity. A reevaluation of the EF hypothesis in children with TS is suggested.

Genetics and epidemiology of Tourette syndrome

Although the genetic basis of Tourette syndrome is well established, uncertainty about how best to define and assess the Tourette syndrome phenotype has hampered efforts to identify the genes responsible for susceptibility to the disorder. In addition, such efforts have typically been underpowered or were undertaken before the technology was available to perform systematic genome-wide genetic investigations. The Tourette Syndrome Association International Consortium on Genetics was formed by more than a dozen research groups from around the world to develop common approaches to phenotyping Tourette syndrome and to pool samples for uniform, well-powered genetic investigations. Several recent advances, including the completion of genome-wide scans of affected sib-pairs and large families, show real promise for identifying Tourette syndrome susceptibility genes. In this review, we describe the key epidemiologic, linkage, and association studies in Tourette syndrome and illustrate the strategies currently being used to identify Tourette syndrome genes.

Epidemiological Survey of Tourette Syndrome in Children and Adolescents in Wenzhou of P.R. China

An epidemiological survey on Tourette syndrome (TS) in a developing country is relatively scarce. This study was conducted to investigate the prevalence and distribution of TS in children and juveniles aged 7-16 years in Wenzhou of P.R. China. A total of 9742 children and adolescents were included in this survey. Cross-sectional study with stratified-cluster sampling method was used. The prevalence of TS among school-age children was estimated to be an average of 0.43%. The ratio of male to female was 10.6 to 1 (0.74% for males and 0.07% for females). Pupils in the age range of 7-16 years are more likely to have comorbid disorders. The mean age at onset of TS was 7.7+/-2.7 years, with 45.2% of them at the age of 6-7. The rate of delayed diagnosis, misdiagnosis and misclassification of the syndrome were 78.6, 42.9 and 23.8%, respectively. This survey supports that TS is a common disease prevalent amongst children and juveniles in Wenzhou area of P.R. China, and its incidence was correlated with age and sex and often misdiagnosed and misclassified.

Brain correlates of negative visuospatial priming in healthy children

Inhibitory mechanisms that begin to develop in childhood are essential for efficient and goal-directed behaviors. These inhibitory mechanisms may go awry in several childhood-onset neuropsychiatric disorders, such as Tourette syndrome, obsessive-compulsive disorder and attention deficit hyperactivity disorder. Negative visuospatial priming is a well-established behavioral probe of inhibition that has been used to demonstrate deficits in children with neuropsychiatric disorders of inhibition, but the brain correlates of negative visuospatial priming have not previously been well delineated. In the present study, we use a visuospatial priming paradigm and event-related functional magnetic resonance imaging (fMRI) to probe inhibitory brain mechanisms in healthy children. When subjects performed the control (i.e. neutral) motor task, a network of cortical and subcortical sensorimotor regions was activated. In contrast, during performance of the negative priming (i.e. inhibitory) task, several regions of the prefrontal cortex were selectively engaged. These results support the notion that the prefrontal cortex is involved in inhibitory processing in healthy children and demonstrate that negative visuospatial priming shares brain correlates with other inhibitory tasks. In conjunction with fMRI, the visuospatial priming task described in the current study may be useful for studying the pathophysiology of childhood-onset neuropsychiatric disorders characterized by deficient inhibitory processing.

Reexamining Tic persistence and Tic-associated impairment in Tourette's Disorder: findings from a naturalistic follow-up study

The objective of this study was to assess tic persistence and tic-associated impairment in referred youth with Tourette's Disorder (TD). Subjects were 50 youth (ages 6-17 years) who met DSM-IV diagnostic criteria for TD, were referred to a specialized TD program, and were evaluated by clinical and structured diagnostic interview. Tic severity and impairment was measured using the Yale Global Tic Severity Scale. The total tic score at or above minimal range defined tic persistence, and a TD impairment score at or above moderate range defined tic-associated impairment. Results were assessed during administration of the Kiddie-Schedule for Affective Disorders and Schizophrenia for School-Age Children-Epidemiological Version. Mean age of onset of TD was 5.1 +/- 2.3 years, and mean illness duration was 5.6 +/- 3.2 years. At baseline, 88% of subjects met threshold criteria for at least mild tics, but only 30% met criteria for tic-associated impairment. At 2-year follow-up, 82% of these subjects met criteria for tic persistence (NS change from baseline), but only 14% met criteria for TD-associated impairment (p < .04 change from baseline). Although tics followed a persistent course in the majority of youth with TD, they were infrequently associated with impairment. There was a significant reduction in the proportion of youth with TD impairment from baseline to follow-up. These results support the view that TD is a persistent disorder, but suggest a dissociation between tic persistence and tic-associated dysfunction.

A comparison of the effects of parental risk markers on pre- and perinatal variables in multiple patient cohorts with fetal alcohol syndrome, autism, Tourette syndrome, and sudden infant death syndrome: an enviromic analysis

The prevalence and magnitude of effect of individual risk markers for specific developmental disorders vary widely across diagnostic category. The four study cohorts for this project were patients from four diagnostic registries in North Dakota for fetal alcohol syndrome (FAS), autism, sudden infant death syndrome (SIDS), and Tourette syndrome. These four cohorts were used to estimate prevalence and magnitude of effect of parental risk markers in patients with developmental disabilities. Cases with North Dakota birth certificates were matched with controls. Using birth certificate data, we then examined five parental risk markers for each cohort and estimated direct and indirect effects for each risk marker by cohort. The authors found two significant paternal risk markers (age in SIDS and education in FAS). Significant maternal markers were age in SIDS, education in FAS, autism, and SIDS. Marital status was a significant risk marker in FAS. Effect sizes were estimated using paired t tests, odds ratios, and population attributable risk (PAR) for both direct and indirect effects for each marker. We estimated both direct and indirect effects to allow for direct comparisons of the differential effect estimates of each of these markers. The direct effect of parental markers differs across diagnostic cohorts of patients. Use of cohorts from similar denominator populations obtained from prevalence studies is a useful methodological tool for estimating the prevalence and magnitude of effect of risk markers.

Movement Disorders

This chapter covers five movement disorders: Parkinson's disease, dystonia, tic disorders, Huntington's disease, and essential tremor. These disorders demonstrate many of the most common challenges encountered in the epidemiologic investigation of movement disorders. Each section includes a description of the disease, followed by a review of descriptive studies (disease incidence, prevalence, and mortality studies), and discussion of genetic and environmental risk factors for the disorder. At the end of each section, directions for future studies are discussed.

Tourette's syndrome in Taiwan: an epidemiological study of tic disorders in an elementary school at Taipei County

We have done an epidemiological study in an elementary school with 2000 Taiwanese children aged from 6 to 12 years, and found 11 of them with Tourette's syndrome. The prevalence rate of Tourette's syndrome was around 0.56%. The ratio of male to female was 9 to 2. The comorbid rate of attention-deficit/hyperactivity disorder was 36%, self-injurious behaviors 27%, and obsessive-compulsive behaviors 18%. The familial rate of Tourette's syndrome was 27%. We also found that another 98 children had transient tic disorders. For 73% of patients with mild tics, understanding and acceptance from family, teachers, and friends are the most important things. When tics are so severe that medication is necessary, haloperidol is no longer the first or only choice. We tried clonidine, atypical neuroleptics such as risperidone or olanzapine, or pergolide. The first support group was established in 1999 for children with tics in Taiwan and transformed to Taiwan Tourette Family association in June 2001 to provide further service for Tourette's syndrome.

Translocation breakpoint in two unrelated Tourette syndrome cases, within a region previously linked to the disorder

Tourette syndrome (TS) is a complex neuropsychiatric disorder characterized by both motor and vocal tics. The etiology of TS is poorly understood; however, evidence of genetic transmission arises from family and twin studies. A complex mode of inheritance has been suggested, likely involving contributions of several genes with different effect size. We describe here two unrelated families wherein balanced t(6;8) chromosomal translocations occur in individuals diagnosed with TS. In one of these families, the transmission of the translocation is associated with learning and behavioral difficulties; in the other family, one parent is unaffected and the other cannot be traced, thus transmission cannot be demonstrated and it is possible that the translocation may have occurred de novo. The breakpoint on chromosome 8 occurs within the q13 band in both families, suggesting that a gene or genes in this region might contribute to the TS phenotype. Existing linkage and cytogenetic data, suggesting involvement of chromosome 8 in TS families and individuals, further support this hypothesis. We have identified two YAC clones mapping distal and proximal to the chromosome 8 translocation site, as determined by fluorescent in situ hybridization (FISH). PCR amplification of genetic markers in this region, using isolated chromosomes from one of the patients, followed by BAC screening with the closest flanking genetic markers, has identified a 200-kb BAC, which, by FISH, we have demonstrated encompasses the chromosome 8 breakpoint in both families. The fact that the chromosomal breaks in the TS cases from both families occur within such a small region of chromosome 8 further supports the hypothesis that disruption of a gene or genes in this part of chromosome 8 contributes to the clinical phenotype.

Movement disorders in children and adolescents

Tourette syndrome (TS), Sydenham chorea, and drug-induced dyskinesias are prototypical movement disorders affecting children. Underlying involvement of basal ganglia has been apparent for several decades, but new neuroimaging studies are adding detail to this mechanism. Genetic studies of TS and tardive dyskinesia may further reveal the underlying pathophysiology. Most provocative is the new conceptual model of poststreptococcal autoimmune neuropsychiatric disorder. Although unproven, substantial support for this model comes from immunologic, family, neuroimaging, and treatment studies.

Tics and problem behaviors in schoolchildren: prevalence, characterization, and associations

OBJECTIVE

Tic disorders are the most common movement disorder diagnosed in children and have symptoms that fluctuate in frequency and intensity over time. We conducted an 8-month longitudinal observational study to determine the variations in frequency of motor tics and associated problem behaviors.

METHODS

A total of 553 children, kindergarten through sixth grade, were observed monthly from November 1999 to June 2000 by 3 raters. Motor tics were recorded by location and rated for severity as none (0), mild (1), moderate (2), or severe (3). Problem behaviors were rated as absent (0), subclinical (1), or clinical (2) in each of 6 categories: disruptive, hyperactive, impulsive, aggressive, anxious, and distracted.

RESULTS

The monthly point prevalence of motor tics ranged from 3.2% to 9.6%, with an overall frequency of 24.4%. The monthly point prevalence of problem behaviors ranged from 2.6% to 11.0%, with an overall frequency of 25.7%. The incidence of motor tics and problem behaviors was significantly higher during the winter months of November through February, compared with the spring months of March through June (motor tics: z = 4.97; problem behaviors: z = 3.79). Motor tics were observed in 2 distinct patterns (isolated and persistent), which varied by the number of months present, gender ratio of affected children, severity of tic symptoms, and association with problem behaviors.

CONCLUSIONS

Motor tics and problem behaviors are frequent occurrences among schoolchildren and seem to occur more frequently during the winter months. For most children, the tics were mild, observed on only 1 occasion, and were not accompanied by problem behaviors.

Tourette syndrome: clinical characteristics and current management strategies

Tourette Syndrome (TS) is a disorder comprised of involuntary motor and phonic tics often associated with psychiatric conditions. The etiology for TS is unclear, with both genetic and immunological theories being studied to date. When pharmacotherapy is considered by the patient and physician to be required, owing to either functional impairment from tics or comorbid psychiatric illness, dopamine receptor antagonists are commonly used. Our first-line agents for tic suppression include clonidine, guanfacine, clonazepam and baclofen. Should these agents be ineffective, we would recommend pimozide, fluphenazine, risperidone or haloperidol. The potential benefit of other agents, such as olanzapine, ziprasidone, pergolide and botulinum toxin, is encouraging. Despite many years of concern, we have found little exacerbation of tics with stimulant medications for attention deficit hyperactivity disorder, but clearly clonidine and guanfacine can ameliorate both comorbid conditions. Obsessive compulsive disorder, when associated with TS, may be treated with either a selective serotonin reuptake inhibitor in association with a dopamine receptor antagonist or risperidone alone. New therapies for all aspects of TS and its comorbid conditions are in active clinical trials.

Tics and its disorders

Tourette syndrome (TS) is familial neuropsychiatric disorder that is characterized by motor and phonic tics that begin in childhood. Once thought of as a rare and debilitating disorder, in the last decade new scientific knowledge suggests that TS and related tic disorders are more common and less debilitating for the majority of individuals. Evidence points toward a spectrum of TS symptomatology that extends beyond the tics disorder to probably include obsessive-compulsive disorder, attention deficit hyperactivity disorder, and mood disorders. Tourette syndrome and its differential diagnosis are discussed in this article with a focus on new developments in classification, etiology, epidemiology, genetics, pathophysiology, and clinical management.

Candidate region for Gilles de la Tourette syndrome at 7q31

Gilles de la Tourette Syndrome (GTS) is a complex neuropsychiatric disorder characterized by motor and vocal tics. The cause of this syndrome is unknown, although based on family studies there is evidence of a strong genetic component. We report on a 13-year-old boy with GTS, minor physical anomalies, and a de novo partial duplication of chromosome 7q [dup(7)(q22.1-q31.1)]. The distal breakpoint in our patient is similar to the breakpoint of an apparently balanced familial translocation t(7;18) segregating with GTS. Together, these cases provide evidence that a gene located in the breakpoint region at 7q31 can be involved in the formation of GTS.

Neuropsychiatric genetics: misclassification in linkage studies of phenotype-genotype research

Research on neuropsychiatric disorders has produced a number of very important findings in the last few decades. However, several problems continue to hinder research in this area. One problem area has been the appropriate classification of disease status for probands and extended family members in linkage studies. In this article, we examine rates of misclassification in a 12-year follow-up study of children previously diagnosed with Tourette syndrome. At the 12-year follow-up, we found a 5 to 12% rate of misclassification of previously diagnosed cases. We present a model of a linkage study with three classification steps. The model demonstrates that an error rate of 5% would result in misclassification of 20% of true cases by step three. Adding additional steps to improve diagnostic accuracy may increase rather than decrease classification error.

Sex steroids and human behavior: implications for developmental psychopathology

In a variety of mammalian species, prenatal androgens organize brain structures and functions that are later activated by steroid hormones in postnatal life. In humans, studies of individuals with typical and atypical development suggest that sex differences in reproductive and nonreproductive behavior derive in part from similar prenatal and postnatal steroid effects on brain development. This paper provides a summary of research investigating hormonal influences on human behavior and describes how sex differences in the prevalences and natural histories of developmental psychopathologies may be consistent with these steroid effects. An association between patterns of sexual differentiation and specific forms of psychopathology suggests novel avenues for assessing the effects of sex steroids on brain structure and function, which may in turn improve our understanding of typical and atypical development in women and men.

Tourette's disorder: epidemiology and comorbidity in primary school children

OBJECTIVE

To study prevalence and comorbidity of Tourette's disorder in the general population of children and in a clinical setting.

METHODS

School-age children in the general population and children attending a county-wide tic disorder clinic were screened and examined by the same doctor. Behavioral-psychometric instruments with demonstrated reliability and validity were used.

RESULTS

Depending on the sample characteristics, 0.15% to 1.1% of all children had Tourette's disorder. Boys outnumbered girls by 4:1 through 6:1. Attention deficits and empathy/autism spectrum problems (including Asperger's disorder) were very common, each type of comorbidity affecting approximately two thirds of individuals with Tourette's disorder. Overall behavior problem scores were high, and affected children exhibited a marked degree of functional impairment.

CONCLUSIONS

Tourette's disorder is a common disorder with high rates of significant comorbidity. In most cases, attention deficits and empathy problems are likely to cause more suffering than the tics per se.

Peek-a-boo fragile site at 16d associated with Tourette syndrome, bipolar disorder, autistic disorder, and mental retardation

Five patients with a fragile site at 16q22-23 and neuropsychiatric disorders are reported. Three of five had Tourette disorder, three had mental retardation, two had bipolar disorder, and one had autistic disorder. During our attempts to study the fragile sites in more detail we were unable to reproduce the fragile sites found several years earlier. The potential relationship between the fragile sites and the neuropsychiatric disorders in these patients is discussed. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:69-73, 2000.

Prenatal and perinatal risk factors for Tourette disorder

AIMS

To identify pre- and perinatal risk factors for Tourette disorder.

METHODS

Case control study. We matched names of patients who met DSM criteria for Tourette disorder with their birth certificates. For each case five controls were selected. The controls were matched by sex, year and month of birth.

RESULTS

Univariate analysis of the 92 cases and the 460 matched controls identified 4 risk factors; one categorical variable--trimester prenatal care begun and 3 continuous variables--apgar score at 5 minutes, month prenatal began and number of prenatal visits. Logistic modeling to control for confounding produced a three variable model (apgar score at 5 minutes (OR = 1.31), number of prenatal visits (OR = .904) and fathers age (OR = .909). The model parameters were: chi 2 = 19.76; df = 3; p < .001.

CONCLUSIONS

This is an inexpensive methodology to identify potential risk factors of patients with Tourette disorder and other mental illness.

A double-blind, placebo-controlled, crossover trial of an antiandrogen in the treatment of Tourette's syndrome

The objective of this study was to document the effects of androgen receptor blockade on tic and obsessive-compulsive symptoms in Tourette's syndrome (TS) patients. Thirteen adult TS subjects, 10 men and 3 women, completed 3 weeks of each phase of a double-blind, placebo-controlled, crossover trial of flutamide, a selective androgen receptor antagonist. Symptom severity ratings and hormone levels were obtained at each of the trial's six clinic visits. Flutamide was well-tolerated and produced a significant reduction in motor but not phonic tic symptom severity. It modestly improved symptoms of obsessive-compulsive disorder in the men who had this disorder. Changes in hormone levels during flutamide administration provided evidence for the existence of physiologic mechanisms that compensate for the blocking of the androgen receptor. The therapeutic effects of flutamide are modest in magnitude and they seem to be short-lived, possibly because of physiologic compensation for androgen receptor blockade. Given the potentially serious side effects of flutamide, the use of this agent in the treatment of tics should be reserved for patients who have relatively debilitating symptoms. The therapeutic and endocrine findings may have implications for understanding the sex differences in TS prevalence and the sex-specific variability in the phenotypic expression of the putative TS vulnerability genes.

Course of tic severity in Tourette syndrome: the first two decades

OBJECTIVE

Prevalence studies indicate a 10-fold higher rate of Tourette syndrome (TS) among children compared with adults. The purpose of this investigation was to examine the course of tic severity during the first 2 decades of life.

METHOD

A birth-year cohort of 42 TS patients followed at the Yale Child Study Center was recontacted an average of 7.3 years after their initial clinical evaluation. Data concerning the onset and course of tic severity until 18 years of age were available on 36 TS patients. A variety of statistical techniques were used to model aspects of the temporal patterning of tic severity.

RESULTS

Mean (SD) tic onset at 5.6 (2. 3) years of age was followed by a progressive pattern of tic worsening. On average, the most severe period of tic severity occurred at 10.0 (2.4) years of age. In eight cases (22%), the frequency and forcefulness of the tics reached a severe level during the worst-ever period such that functioning in school was impossible or in serious jeopardy. In almost every case this period was followed by a steady decline in tic severity. By 18 years of age nearly half of the cohort was virtually tic-free. The onset of puberty was not associated with either the timing or severity of tics.

CONCLUSIONS

A majority of TS patients displayed a consistent time course of tic severity. This consistency can be accurately modeled mathematically and may reflect normal neurobiological processes. Determination of the model parameters that describe each patient's course of tic severity may be of prognostic value and assist in the identification of factors that differentially influence the course of tic severity.

Tic disorders

The picture that emerges is one of complex behavioral phenotypes that alter over the course of CNS development. While many cases are mild and may not come to medical attention, others are chronic and disabling. The aim of this article is to provide an overview of recent progress in understanding phenomenology, epidemiology, genetics, neurobiology, and treatment of tic disorders.

Epidemiology of Tourette syndrome

The epidemiology of Tourette syndrome is difficult to characterize because there is no definitive diagnosis. Symptom intensity and frequency decrease with age and in social situations, and affected individuals are often unaware of their tics. This chapter reviews and summarizes current data on the prevalence, distribution, and risk factors for Tourette syndrome.

Pathogenesis of Tourette's syndrome

This review presents a models of disease pathogenesis in the context of CNS development. It begins with an exploration of the clinical features and natural history of Tourette's syndrome. This is followed by a consideration of the role of genetic and nongenetic factors. An effort is then made to review the anatomical organization of the basal ganglia and related cortical sites. These circuits are intimately involved in the normal processing of sensorimotor, cognitive, and emotionally laden information. Evidence implicating these circuits in the pathobiology of Tourette's syndrome is then considered. The review closes with the prospects for advances in interdisciplinary research and therapeutics using this model as a guide.

The physiological threat of compulsive syndromes

Compulsive syndromes, especially obsessive-compulsive disorder, are much more common than previously believed. The behaviours that are a part of these syndromes can lead to physiologically threatening conditions whose medical consequences range from minor to fatal. It is crucial that not only mental health professionals, but all health professionals better understand the nature and consequences of compulsive disorders and their importance to general health.

Observations and ratings of tics in school settings

This paper describes the findings of a school-based tic assessment procedure (direct observations, teacher rating scales) for hyperactive children with comorbid tic disorder. Rates of motor tic frequency were found to be moderately stable across both days and school settings. Correlations between direct observations of tics and clinician rating scales were generally in the low to moderate range as were correlations between teacher and clinician rating scales. Overall rates of hyperactive/disruptive behaviors were not associated with rates of motor tic occurrence, and the behavioral symptoms of both disorders were also independent for specific intervals of time.

Neurobiological issues in Tourette syndrome

The Tourette syndrome (TS) represents an intriguing disorder that overlaps the clinical fields of neurology and psychiatry. Composed of a spectrum of familial, involuntary motor and vocal tics and co-morbid neuropsychological problems, this disorder has become a model for investigators interested in neurobehavioral research. Although the subject of numerous reports since Tourette's original description in 1885, over the past decade there has been a rapid expansion of knowledge pertaining to the phenomenology of tic syndromes and their associated problems, the role of genetic and environmental factors, and the underlying pathophysiology. The role of frontal-subcortical circuits, dopaminergic neurotransmission, and second messenger systems are highlighted. This report provides a framework for understanding current neurobiological issues in TS.

The clinical features of Tourette's disorder: an Australian study using a structured interview schedule

The clinical features of an Australian series of patients fulfilling DSM-III-R criteria for Tourette's Syndrome (TS) were examined. Fifty patients, recruited from a hospital-based outpatient clinic and a self-help group, were interviewed using a structured schedule. TS is a complex disorder with wide ranging manifestations. Forty male and ten female TS patients with a mean age of 20.8 years (SD 11.2) were assessed. The mean age of onset of tics was 8.3 years (SD 3.3). Simple motor tics occurring in the rostral body regions were more common (eye 86%, face and head 80%) when compared both to simple tics occurring caudally (leg 52%) and complex motor tics (58%). Simple vocal tics were more common (94%) than complex ones (44%). There was a rostrocaudal pattern in the age of onset and severity of simple motor tics. Rates of comorbidity were 32%, 18% and 30% for Attention-Deficit Hyperactivity Disorder, Major Depression and Generalised Anxiety Disorder respectively and this was reflected in the considerable proportion (32%) of the sample who first presented for reasons other than their tics. There were substantial delays between the age of first presentation and diagnosis of TS owing to the insidious onset of the disorder, misdiagnosis and delays in presentation for help. A comparison of the features of the present patients with those of other published studies revealed similarities with some differences. Better clinical recognition of the symptoms and modes of presentation of TS may improve existing delays in diagnosis and treatment.

Clinical and genetic relationships between autism-pervasive developmental disorder and Tourette syndrome: a study of 19 cases

Children with autism or pervasive developmental disorder (PDD) and Tourette syndrome (TS) share a number of symptoms. Forty-one cases have been reported in which PDD patients subsequently developed TS. We term this PDD----TS. We describe an additional 16 such patients plus 3 families where a close relative of a TS proband had autism. There was a high frequency of alcoholism, drug abuse, obsessive-compulsive, and other behavior disorders in the relatives of these patients. This frequency was virtually identical to that observed in relatives of individuals with TS only. We suggest there is an intimate genetic, neuropathologic relatedness between some cases of PDD and TS. Many observations have led us to suggest that the genetic defect in TS may be a mutation of tryptophan oxygenase and that TS is inherited as a semidominant semirecessive trait, i.e., homozygosity for a common gene which shows some expression in the heterozygous state. We propose that some types of PDD are inherited in the same fashion and by the same gene. This would explain the similarity of symptoms, frequent evolution of PDD into TS, the apparent recessive inheritance of PDD despite no increase in consanguinity, the high frequency of behavior problems in the relatives of PDD----TS patients and the serotonin abnormalities.

Huntington disease and childhood-onset Tourette syndrome

A 40-year-old man with childhood-onset Tourette syndrome (TS) developed Huntington disease (HD). We believe this to be the first reported case of childhood-onset TS with adult onset HD. Discovery of other cases with both disorders may provide clues to the pathophysiology of both conditions.

Prevalence study of Rett syndrome in North Dakota children

Service providers for children in the state of North Dakota were surveyed to determine the prevalence rate of Rett syndrome (RS). Five patients with definite RS were identified in a population of 203,801 children (98,932 girls) 0-18 years of age yielding a prevalence rate of RS of 1 in 40,760 in North Dakota children. For girls the rate of RS is 1 in 19,786. Similar surveys of other states using comparable modes of ascertainment will be important as points of comparison for prevalence rates of RS.

Hypothesis: homozygosity in Tourette syndrome

We review evidence suggesting that many individuals with Tourette syndrome (TS) may be homozygous for a "Tourette syndrome" gene. This is based on experience with pedigrees on 1,200 TS families, comparison of the occurrence of tics or associated behaviors such as obsessive-compulsive behavior, panic attacks, attention deficit hyperactivity disorder, and/or severe alcohol or drug abuse, on both the maternal and paternal side in 170 TS families compared to control families, biochemical studies of blood serotonin and tryptophan levels, and other evidence. These observations suggest the inheritance in TS may be best described as semi-dominant, semi-recessive. Some of the implications of this proposal are discussed.