Children at familial risk for Tourette's disorder: Child and parent diagnoses

We've all been wrong about provisional tic disorder

BACKGROUND

Provisional Tic Disorder (PTD) is common in childhood. The received wisdom among clinicians is that PTD is short-lived and mild, with at most a few tics, and rarely includes complex tics, premonitory phenomena or comorbid illnesses. However, such conclusions come from clinical experience, with biased ascertainment and limited follow-up.

METHODS

Prospective study of 89 children with tics starting 0-9 months ago (median 4 months), fewer than half from clinical sources. Follow-up at 12 (± 24, 36, 48) months after the first tic.

RESULTS

At study entry, many children had ADHD (39), an anxiety disorder (27), OCD (9) or enuresis (17). All had at least two current tics, with a mean total since onset of 6.9 motor and 2.0 phonic tics. Forty-one had experienced a complex tic, and 69 could suppress some tics. Tics were clinically meaningful: 64 had tics severe enough for a clinical trial, and 76 families sought medical attention for the tics. At 12 months, 79 returned, and 78 still had tics. Of these, 29 manifested no tics during history and extended examination, but only via audio-visual monitoring when the child was seated alone. Only 12/70 now had plans to see a doctor for tics. Most who returned at 2-4 years still had tics known to the child and family, but medical impact was low.

CONCLUSIONS

Our results do not contradict previous data, but overturn clinical lore. The data strongly argue against the longstanding but arbitrary tradition of separating tic disorders into recent-onset versus chronic.

"Sorry, I Didn't Mean to Kiss at You": A Descriptive Analysis of Tourette Syndrome in Interpersonal Interactions

Recent research has begun to explore the specific social challenges experienced by persons with Tourette syndrome (TS); however, it does not specifically address the challenges that often arise interpersonally as part of people's communicative interactions and these interactions socially construct the individual and collective well-being of all involved. This study conducted semi-structured interviews with 18 adults who identified as having TS in order to investigate the ways in which others respond behaviorally to TS behaviors and the ways TS behaviors are misinterpreted within interpersonal interactions. Thematic analysis was used to identify themes common within participant responses. All participants reported receiving unwanted attention from others in response to their TS symptoms. Unwanted attention was further divided into six emergent subthemes, including verbal harassment, physical abuse, staring, general bullying, getting into trouble, and being kicked out. Three types of misunderstandings were also reported in interpersonal interactions: misunderstanding communicative intention, misunderstanding TS, and misunderstanding the cause of TS behaviors. Applying attribution theory, it is determined that it is ultimately the misattribution of communicative intent to TS behaviors that causes many misunderstandings reported by adults with TS and leads to a plethora of interpersonal, communicative challenges. Importantly, these misunderstandings are what ultimately contribute to much of the unwanted attention described by the participants in this study and documented in previous work, highlighting the value of a greater awareness of how misunderstandings take place with respect to TS.

Lack of Association of Group A Streptococcal Infections and Onset of Tics: European Multicenter Tics in Children Study

ObjectiveTo investigate the association between Group-A streptococcal (GAS) infections and tic incidence among unaffected children with a family history of chronic tic disorders (CTD).MethodsIn a prospective cohort study, children with no history for tics aged 3 to 10 years with a first-degree relative with CTD were recruited from the European Multicentre Tics in Children Study (EMTICS) across 16 European centres. Presence of GAS infection was assessed using throat swabs, serum Anti-streptolysin O titres (ASOT) and Anti-DNAse B (ADB) titres blinded to clinical status. GAS exposure was defined using four different definitions based on these parameters. Cox regression analyses with time-varying GAS exposure were conducted to examine the association of onset of tics and GAS exposure during follow-up. Sensitivity analyses were conducted using Cox regression and logistic regression analyses.ResultsA total of 260 children were recruited whilst one subject was found to have tic onsets before study entry and therefore was excluded. 61 children (23.6%) developed tics over an average follow-up period of 1 (SD 0.7) year. There was a strong association of sex and onset of tics, with girls having an approximately 60% lower risk of developing tics compared to boys (HR: 0.4, 95% CI 0.2-0.7). However, there was no statistical evidence to suggest an association of any of the four GAS exposure definitions with tic onset (GAS exposure definition 1: HR=0.310, 95% CI: 0.037-2.590; definition 2: HR=0.561, 95% CI: 0.219-1.436; definition 3: HR=0.853, 95% CI: 0.466-1.561; definition 4: HR=0.725, 95% CI: 0.384-1.370).ConclusionThese results do not suggest an association of GAS exposure and development of tics.Classification of EvidenceThis study provides Class I evidence that Group-A streptococcal exposure does not associate with the development of tics in children with first-degree relatives with chronic tic disorder.

Pharmacological therapy for Tourette syndrome: What medicine can do and cannot do

Tourette syndrome (TS) is a frequently observed developmental neuropsychological disorder occurring in children. The pathophysiology involves both genetic and environmental factors. In this review, clinical characteristics, pathophysiology, and treatment approaches based on the pathophysiology of TS are presented. The pathophysiology is the acceleration of developmental decrement of dopamine (DA) activity at the terminal of nigro-striatal (NS)-DA system causing DA D2 receptor up-ward regulation. Serotonergic neurons involving in development of the biphasic sleep-wake-rhythm, and locomotion may be involved. Pharmacological treatments constitute an important part in managing TS. Small dose of levodopa and aripiprazole showed the good effect controlling the tics, without side effects. Intervention with enhancing the day time activity and keeping the regular sleep-wake-rhythm, and encouraging locomotion are important. The data from Yoshiko Nomura Neurological Clinic for Children regarding the clinical features and outcomes, medication effects, and OCD and outcomes are shown. To discuss about the environmental factor, how the COVID-19 pandemic affected the TS patients is also presented.

Course of tic disorders over the lifespan

PURPOSE OF REVIEW

To summarize and update information on the course of tic disorders from childhood through later life.

RECENT FINDINGS

Tics tend to improve substantially over the first year after they appear. However, contrary to widespread opinion, tics usually last longer than one year, though usually at minimal severity. Tics often wane to clinical insignificance over the teen years, possibly resurging occasionally over the lifespan. However, in an important minority of patients, tics remain clinically relevant throughout life. Tics rarely first come to clinical attention later in adulthood, but new reports describe additional such cases.

SUMMARY

Recent publications have shown tics to persist past a few months more often than previously thought, though often at minimal severity, and recurrence after an asymptomatic period is common. The safety and efficacy of behavior therapy for tics, together with prospective indicators of early prognosis, make feasible the possibility of bettering the lifetime course of tic disorders with early intervention.

Association between allergic conjunctivitis and provisional tic disorder in children

BACKGROUND

Allergic diseases are associated with a higher risk of Tourette's syndrome (TS). Provisional tic disorder (PTD) and eye blinking are often reported as the initial symptoms both in TS and in allergic conjunctivitis (AC).

OBJECTIVE

To investigate the association between AC and PTD in children of 4-10 years of age in southwest China.

METHODS

This case-control study was carried out at the Children's Hospital of Chongqing Medical University between January 2016 and June 2017. Age- and gender-matched children without PTD were included as the control group. Intraocular pressure was measured by non-contact tonometry, tear film break-up time by slit-lamp examination, and allergens by skin prick test (SPT). Multivariable logistic regression analysis was applied to adjust for the simultaneous effects of AC, dry eye, and allergic history in children with PTD.

RESULTS

The frequency of AC was higher in the PTD group (74.3%, 52/70) than in the control group (17.1%, 12/70) (P < 0.001). The frequencies of positive SPT were found to be higher in the PTD group (80.0%, 56/70) than in the control group (20.0%, 14/70). AC, dry eye, and history of allergic rhinitis were significantly associated with PTD.

CONCLUSION

The frequencies of AC are high in children with PTD. AC and dry eye may be both associated with PTD in children.

European Multicentre Tics in Children Studies (EMTICS): protocol for two cohort studies to assess risk factors for tic onset and exacerbation in children and adolescents

Genetic predisposition, autoimmunity and environmental factors [e.g. pre- and perinatal difficulties, Group A Streptococcal (GAS) and other infections, stress-inducing events] might interact to create a neurobiological vulnerability to the development of tics and associated behaviours. However, the existing evidence for this relies primarily on small prospective or larger retrospective population-based studies, and is therefore still inconclusive. This article describes the design and methodology of the EMTICS study, a longitudinal observational European multicentre study involving 16 clinical centres, with the following objectives: (1) to investigate the association of environmental factors (GAS exposure and psychosocial stress, primarily) with the onset and course of tics and/or obsessive-compulsive symptoms through the prospective observation of at-risk individuals (ONSET cohort: 260 children aged 3-10 years who are tic-free at study entry and have a first-degree relative with a chronic tic disorder) and affected individuals (COURSE cohort: 715 youth aged 3-16 years with a tic disorder); (2) to characterise the immune response to microbial antigens and the host's immune response regulation in association with onset and exacerbations of tics; (3) to increase knowledge of the human gene pathways influencing the pathogenesis of tic disorders; and (4) to develop prediction models for the risk of onset and exacerbations of tic disorders. The EMTICS study is, to our knowledge, the largest prospective cohort assessment of the contribution of different genetic and environmental factors to the risk of developing tics in putatively predisposed individuals and to the risk of exacerbating tics in young individuals with chronic tic disorders.

Systematic review of co-occurring OCD and TD: Evidence for a tic-related OCD subtype?

OBJECTIVE

The aim of this review is to summarize the current knowledge of associated features of co-occurring obsessive-compulsive disorder (OCD) and tic disorders (TD) and to critically evaluate hypotheses regarding the nature of their comorbidity.

METHOD

We conducted a systematic review following PRISMA guidelines. To this aim, the PubMed, PsychInfo and ISI Web of Knowledge databases were searched up to August 30, 2018. For gender and age-of-onset we additionally conducted meta-analyses.

RESULTS

One hundred eighty-nine studies met inclusion criteria. We substantiate some acknowledged features and report evidence for differential biological mechanisms and treatment response. In general, studies were of limited methodological quality.

CONCLUSIONS

Several specific features are reliable associated with co-occurring OCD + TD. The field lacks methodological sound studies. The review found evidence against and in favor for different hypotheses regarding the nature of comorbidity of OCD and TD. This could indicate the existence of a stepwise model of co-morbidity, or could be an artefact of the low methodological quality of studies.

The bird dancer and the warrior king: Divergent lived experiences of Tourette syndrome in Bali

In the past two decades, ethnographic, epidemiological and interdisciplinary research has robustly established that culture is significant in determining the long-term outcomes of people with neurodevelopmental, neuropsychiatric and mood disorders. Yet these cultural factors are certainly not uniform across discrete individual experiences. Thus, in addition to illustrating meaningful differences for people with neuropsychiatric disorder between different cultures, ethnography should also help detail the variations within a culture. Different subjective experiences or outcomes are not solely due to biographical idiosyncrasies-rather, influential factors arising from the same culture can have different impacts on different people. When taking a holistic and intersectional perspective on lived experience, it is crucial to understand the interaction of these factors for people with neuropsychiatric disorders. This paper teases apart such interactions, utilizing comparative case studies of the disparate subjective experiences and illness trajectories of two Balinese people with Tourette syndrome who exhibit similar symptoms. Based on longitudinal person-centered ethnography integrating clinical, psychological, and visual anthropology, this intersectional approach goes beyond symptom interpretation and treatment modalities to identify gendered embodiment and marital practices as influenced by caste to be significant determinants in subjective experience and long-term outcome.

Provisional Tic Disorder: What to tell parents when their child first starts ticcing

The child with recent onset of tics is a common patient in a pediatrics or child neurology practice. If the child’s first tic was less than a year in the past, the diagnosis is usually Provisional Tic Disorder (PTD). Published reviews by experts reveal substantial consensus on prognosis in this situation: the tics will almost always disappear in a few months, having remained mild while they lasted. Surprisingly, however, the sparse existing data may not support these opinions.

PTD may have just as much importance for science as for clinical care. It provides an opportunity to prospectively observe the spontaneous remission of tics. Such prospective studies may aid identification of genes or biomarkers specifically associated with remission rather than onset of tics. A better understanding of tic remission may also suggest novel treatment strategies for Tourette syndrome, or may lead to secondary prevention of tic disorders.

This review summarizes the limited existing data on the epidemiology, phenomenology, and outcome of PTD, highlights areas in which prospective study is sorely needed, and proposes that tic disorders may completely remit much less often than is generally believed.

Advances in Tourette syndrome: diagnoses and treatment

Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder characterized by multiple motor tics and at least one vocal or phonic tic, and often one or more comorbid psychiatric disorders. Premonitory sensory urges before tic execution and desire for "just-right" perception are central features. The pathophysiology involves cortico-striato-thalamo-cortical circuits and possibly dopaminergic system. TS is considered a genetic disorder but the genetics is complex and likely involves rare mutations, common variants, and environmental and epigenetic factors. Treatment is multimodal and includes education and reassurance, behavioral interventions, pharmacologic, and rarely, surgical interventions.

The Tourette International Collaborative Genetics (TIC Genetics) study, finding the genes causing Tourette syndrome: objectives and methods

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by recurrent motor and vocal tics, often accompanied by obsessive-compulsive disorder and/or attention-deficit/hyperactivity disorder. While the evidence for a genetic contribution is strong, its exact nature has yet to be clarified fully. There is now mounting evidence that the genetic risks for TS include both common and rare variants and may involve complex multigenic inheritance or, in rare cases, a single major gene. Based on recent progress in many other common disorders with apparently similar genetic architectures, it is clear that large patient cohorts and open-access repositories will be essential to further advance the field. To that end, the large multicenter Tourette International Collaborative Genetics (TIC Genetics) study was established. The goal of the TIC Genetics study is to undertake a comprehensive gene discovery effort, focusing both on familial genetic variants with large effects within multiply affected pedigrees and on de novo mutations ascertained through the analysis of apparently simplex parent-child trios with non-familial tics. The clinical data and biomaterials (DNA, transformed cell lines, RNA) are part of a sharing repository located within the National Institute for Mental Health Center for Collaborative Genomics Research on Mental Disorders, USA, and will be made available to the broad scientific community. This resource will ultimately facilitate better understanding of the pathophysiology of TS and related disorders and the development of novel therapies. Here, we describe the objectives and methods of the TIC Genetics study as a reference for future studies from our group and to facilitate collaboration between genetics consortia in the field of TS.

Involvement of tryptophan hydroxylase 2 gene polymorphisms in susceptibility to tic disorder in Chinese Han population

Background

Tryptophan hydroxylase-2 (TPH2) is a potential candidate gene for screening tic disorder (TD).

Methods

A case–control study was performed to examine the association between the TPH2 gene and TD. The Sequenom® Mass ARRAY iPLEX GOLD System was used to genotype two single nucleotide polymorphisms (SNPs) of the TPH2 gene in 149 TD children and in 125 normal controls.

Results

For rs4565946, individuals with the TT genotype showed a significantly higher risk of TD than those with TC plus CC genotypes [odds ratio (OR) =3.077, 95% confidence interval (CI): 1.273–7.437; P = 0.009], as did male TD children with the TT genotype (OR = 3.228, 95% CI: 1.153–9.040; P = 0.020). The G allele of rs4570625 was significantly more frequent in TD children with higher levels of tic symptoms (Yale Global Tic Severity Scale, YGTSS) than those in controls among the male children (OR = 1.684, 95%: 1.097–2.583; P = 0.017]. TD children with severe tic symptoms had significantly higher frequencies of rs4546946 TT genotype than did normal controls in boys (OR = 3.292, 95% CI: 1.139–9.513; P = 0.022). We also found that genotype distributions of both SNPs were different between the Asian and European populations.

Conclusions

Our results indicated that the TT genotype of rs4565946 is a potential genetic risk factor for TD, and the allele G of rs4570625 might be associated with the severity of tic symptoms in boys. These polymorphisms might be susceptibility loci for TD in the Chinese Han population. Because of the confounding of co-existing attention deficit hyperactivity disorder (ADHD),these findings need to be confirmed by studies in much larger samples.

Neurobiology of tourette syndrome: current status and need for further investigation

Tourette syndrome (TS) is a common, chronic neuropsychiatric disorder characterized by the presence of fluctuating motor and phonic tics. The typical age of onset is ∼5-7 years, and the majority of children improve by their late teens or early adulthood. Affected individuals are at increased risk for the development of various comorbid conditions, such as obsessive-compulsive disorder, attention deficit hyperactivity disorder, school problems, depression, and anxiety. There is no cure for tics, and symptomatic therapy includes behavioral and pharmacological approaches. Evidence supports TS being an inherited disorder; however, the precise genetic abnormality remains unknown. Pathologic involvement of cortico-striatal-thalamo-cortical (CSTC) pathways is supported by neurophysiological, brain imaging, and postmortem studies, but results are often confounded by small numbers, age differences, severity of symptoms, comorbidity, use of pharmacotherapy, and other factors. The primary site of abnormality remains controversial. Although numerous neurotransmitters participate in the transmission of messages through CSTC circuits, a dopaminergic dysfunction is considered a leading candidate. Several animal models have been used to study behaviors similar to tics as well as to pursue potential pathophysiological deficits. TS is a complex disorder with features overlapping a variety of scientific fields. Despite description of this syndrome in the late 19th century, there remain numerous unanswered neurobiological questions.

Tourette syndrome and other tic disorders

Tic disorders, including Tourette syndrome, are an intriguing group of paroxysmal movement abnormalities that begin in childhood, have a fluctuating course, are capable of causing psychosocial and physical problems, and often improve by early adulthood. These disorders are frequently associated with a variety of comorbid problems whose negative effects may exceed those of tics. Therapy is strictly symptomatic and usually includes educational, behavioral, and a variety of pharmacological therapies. Although there is strong evidence supporting an inherited basis, the precise genetic abnormality remains unknown. A proposed poststreptococcal autoimmune etiology remains controversial. Pathophysiologically, tics appear to arise from an alteration within cortico-striatal-thalamo-cortical circuits, but the definitive site is unknown. Evidence supports an abnormality of synaptic neurotransmission, likely involving the dopaminergic system.

The familial association of tourette's disorder and ADHD: the impact of OCD symptoms

Tourette's disorder (TD) frequently co-occurs with attention-deficit/hyperactivity disorder (ADHD) and obsessive compulsive disorder (OCD). While the relationship between TD and OCD suggests that they share etiological factors, the exact relationship between TD and ADHD is less clear. The goal of the current analyses was to understand better the familial relationship between DSM-IV ADHD and TD. Direct interview diagnostic data from a case-control study of 692 relatives of 75 comorbid TD and ADHD (TD + ADHD), 74 TD without ADHD (TD Only), 41 ADHD without TD (ADHD Only), and 49 control probands were analyzed. Hierarchical loglinear modeling was used to explore association patterns between TD, ADHD, and OCD or sub-clinical OCD (OCD/OCDsub) diagnoses among the 190 affected probands and their 538 relatives. The presence of OCD or OCDsub diagnosis in a proband was associated with a significantly increased risk of comorbid TD + ADHD in his/her relatives. The finding of an association between TD, ADHD and a proband OCD/OCDsub diagnosis was unexpected. The current results suggest that TD, ADHD, and OCD symptoms have overlapping neurobiology when occurring in families of TD and/or ADHD probands.

Familiality of Tourette syndrome, obsessive-compulsive disorder, and attention-deficit/hyperactivity disorder: heritability analysis in a large sib-pair sample

OBJECTIVE

Tourette syndrome (TS) is a neuropsychiatric disorder with a genetic component that is highly comorbid with obsessive-compulsive disorder (OCD) and attention deficit/hyperactivity disorder (ADHD). However, the genetic relations between these disorders have not been clearly elucidated. This study examined the familial relations among TS, OCD, and ADHD in a large sample of TS families.

METHOD

Parent-offspring concordance of TS, OCD, and ADHD was examined in 952 individuals from 222 TS-affected sib-pair families originally collected for genetic studies using logistic regression with generalized estimating equations to control for correlated data. Variance components methods were used to estimate the heritability and genetic and environmental correlations among TS, OCD, and ADHD. Bilineal families where both parents had TS or OCD were excluded.

RESULTS

OCD and ADHD were highly heritable in these TS families. There were significant genetic correlations between TS and OCD and between OCD and ADHD, but not between TS and ADHD. In addition, significant environmental correlations were found between TS and ADHD and between OCD and ADHD. Parental OCD + ADHD was associated with offspring OCD + ADHD.

CONCLUSIONS

This study provides further evidence for a genetic relation between TS and OCD and suggests that the observed relation between TS and ADHD may due in part be to a genetic association between OCD and ADHD and in part due to shared environmental factors.

The DRD4 gene and severity of tics and comorbid symptoms: main effects and interactions with delivery complications

In this study, we investigated the role of the dopamine receptor D4 (DRD4) 48-base pairs (bp) variable number of tandem repeats (VNTR) and perinatal adversities regarding severity of tics and comorbid symptoms in children with tic disorders. We genotyped 110 children with tics with regard to the 48-bp VNTR and assessed presence of prenatal smoking exposure, and pregnancy and delivery complications by parent questionnaires. We examined associations between 2, 3, 4, and 7 repeat (R) alleles and severity of tics and comorbid obsessive-compulsive, depressive, anxious, and autistic symptoms. Through linear regressions, we investigated whether perinatal adversities and the 2R, 3R, 4R, and 7R alleles would interact with severity ratings of tics or comorbid symptoms as outcome. Presence of a 2R allele was related to more severe obsessive-compulsive symptoms, and presence of a 3R allele to increased severity of autistic features. Pregnancy complications were associated with decreased obsessive-compulsive symptom severity, and prenatal smoking exposure to more severe depressive and autistic symptoms. In children without a 3R allele delivery complications were associated with more severe tics, but in children with a 3R variant an inverse relation between delivery complications and tic severity was found. Moreover, the relation between delivery complications and internalizing symptom severity appeared to be most pronounced in children with a 2R allele. In conclusion, this study provides evidence for a role of the 48-bp VNTR in the etiology of tic and associated disorders, and for interactions with delivery complications regarding severity of tics and co-occurring internalizing symptoms.

Cluster analysis of the Yale Global Tic Severity Scale (YGTSS): symptom dimensions and clinical correlates in an outpatient youth sample

Tic disorders are heterogeneous, with symptoms varying widely both within and across patients. Exploration of symptom clusters may aid in the identification of symptom dimensions of empirical and treatment import. This article presents the results of two studies investigating tic symptom clusters using a sample of 99 youth (M age = 10.7, 81% male, 77% Caucasian) diagnosed with a primary tic disorder (Tourette’s disorder or chronic tic disorder), across two university-based outpatient clinics specializing in tic and related disorders. In Study 1, a cluster analysis of the Yale Global Tic Severity Scale (YGTSS) identified four symptom dimensions: predominantly complex tics; simple head/face tics; simple body tics; and simple vocal/facial tics. In Study 2, these clusters were shown to be differentially associated with demographic and clinical characteristics. Findings lend support to prior research on tic phenomenology, help to organize treatment goals, and suggest symptom dimensions of tic disorders for further evaluation.

Linkage analysis of Tourette syndrome in a large Utah pedigree

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by multiple motor and phonic tics. The heritability of TS has been well established, yet there is a lack of consensus in genome-wide linkage studies. The purpose of this study was to conduct a genome-wide linkage analysis on a unique, large, high-risk TS Utah pedigree. We examined a qualitative trait (TS1) where cases had a definitive diagnosis of TS as observed by a clinical interviewer (n = 66) and a quantitative phenotype based on the total Yale global motor and phonic tic severity scores (n = 102). Both parametric and non-parametric multipoint linkage analyses based on MCMC methods were performed using a 10 cM spaced micro-satellite autosomal marker set. Two regions of interest were identified under affecteds-only recessive models; a LOD score of 3.3 on chromosome 1p for Yale tic severity and a LOD score of 3.1 on chromosome 3p for the TS1 phenotype. Twenty-seven individuals shared linked segregating haplotypes for the 1p region. They had significantly higher Yale tic phonic scores than non-sharers (P = 0.01). There were 46 haplotype sharers on chromosome 3p with significantly higher percentage of females among these individuals compared to the non-sharers (P = 0.03). The significant linkage peaks on chromosomes 1p and 3p are in new areas of the genome for TS, and replication of these findings is necessary.

The genetics of Tourette syndrome: a review

OBJECTIVES

This article summarizes and evaluates recent advances in the genetics of Gilles de la Tourette syndrome (GTS).

METHODS

This is a review of recent literature focusing on (1) the genetic etiology of GTS; (2) common genetic components of GTS, attention deficit hyperactivity disorder (ADHD), and obsessive compulsive disorder (OCD); (3) recent linkage studies of GTS; (4) chromosomal translocations in GTS; and (5) candidate gene studies.

RESULTS

Family, twin, and segregation studies provide strong evidence for the genetic nature of GTS. GTS is a heterogeneous disorder with complex inheritance patterns and phenotypic manifestations. Family studies of GTS and OCD indicate that an early-onset form of OCD is likely to share common genetic factors with GTS. While there apparently is an etiological relationship between GTS and ADHD, it appears that the common form of ADHD does not share genetic factors with GTS. The largest genome wide linkage study to date observed evidence for linkage on chromosome 2p23.2 (P=3.8x10(-5)). No causative candidate genes have been identified, and recent studies suggest that the newly identified candidate gene SLITRK1 is not a significant risk gene for the majority of individuals with GTS.

CONCLUSION

The genetics of GTS are complex and not well understood. The Genome Wide Association Study (GWAS) design can hopefully overcome the limitations of linkage and candidate gene studies. However, large-scale collaborations are needed to provide enough power to utilize the GWAS design for discovery of causative mutations. Knowledge of susceptibility mutations and biological pathways involved should eventually lead to new treatment paradigms for GTS.

Streptococcal infection, Tourette syndrome, and OCD: is there a connection?

BACKGROUND

A causal relationship of common streptococcal infections and childhood neuropsychiatric disorders has been postulated.

OBJECTIVE

To test the hypothesis of an increased rate of streptococcal infections preceding the onset of neuropsychiatric disorders.

METHODS

Case-control study of a large primary care database comparing the rate of possible streptococcal infections in patients aged 2-25 years with obsessive-compulsive disorder (OCD), Tourette syndrome (TS), and tics with that in controls matched for age, gender, and practice (20 per case). We also examined the influence of sociodemographic factors.

RESULTS

There was no overall increased risk of prior possible streptococcal infection in patients with a diagnosis of OCD, TS, or tics. Subgroup analysis showed that patients with OCD had a slightly higher risk than controls of having had possible streptococcal infections without prescription of antibiotics in the 2 years prior to the onset of OCD (odds ratio 2.59, 95% confidence interval 1.18, 5.69; p = 0.02). Cases with TS or tics were not more likely to come from more affluent or urban areas, but more cases lived in areas with a greater proportion of white population (p value for trend = 0.05).

CONCLUSIONS

The present study does not support a strong relationship between streptococcal infections and neuropsychiatric syndromes such as obsessive-compulsive disorder and Tourette syndrome. However, it is possible that a weak association (or a stronger association in a small susceptible subpopulation) was not detected due to nondifferential misclassification of exposure and limited statistical power. The data are consistent with previous reports of greater rates of diagnosis of Tourette syndrome or tics in white populations.

Latent class analysis of gilles de la tourette syndrome using comorbidities: clinical and genetic implications

BACKGROUND

Although susceptibility loci exist for Gilles de la Tourette syndrome (GTS), no causative gene has been identified, perhaps in part because of phenotypic heterogeneity. This study used latent class analyses (LCA) to identify GTS subphenotypes and assess characteristics and heritability of the classes.

METHODS

The study included 952 individuals from 222 GTS families recruited for genetic studies. LCA identified a best-fit model for combinations of the diagnoses of GTS, obsessive-compulsive disorder (OCD), OC symptoms and behaviors (OCS/OCB), and attention-deficit/hyperactivity disorder (ADHD) in a random sample of one sibling from each family (n = 197), a replication sample randomly chosen from the remaining siblings (n = 203), and in the entire sample (all siblings and parents, N = 952). Heritabilities were assessed for all categoric diagnoses and LCA classes using a variance components approach.

RESULTS

In this large sample of GTS sib pairs and their parents, three GTS-affected groups were identified-GTS + OCS/OCB (Class III), GTS + OCD (Class IV), and GTS + OCD + ADHD (Class V)-in addition to a minimally affected class (I) and a small chronic tics + OCD class (II). A preponderance of males and younger age at onset was found in more comorbidly affected classes. Only the GTS + OCD + ADHD class was highly heritable.

CONCLUSIONS

Our data suggest that GTS classes may represent distinct entities, with both shared and unique etiologies. In particular, GTS + OCD + ADHD may represent a separate, heritable phenotype that can be used to further inform genetic studies.

Tourette syndrome and tic disorders: a decade of progress

OBJECTIVE

This is a review of progress made in the understanding of Tourette syndrome (TS) during the past decade including models of pathogenesis, state-of-the-art assessment techniques, and treatment.

METHOD

Computerized literature searches were conducted under the key words "Tourette syndrome," "Tourette disorder," and "tics." Only references from 1996-2006 were included.

RESULTS

Studies have documented the natural history of TS and the finding that tics usually improve by the end of the second decade of life. It has also become clear that TS frequently co-occurs with attention-deficit/hyperactivity disorder), obsessive-compulsive disorder, and a range of other mood and anxiety disorders. These comorbid conditions are often the major source of impairment for the affected child. Advances have also been made in understanding the underlying neurobiology of TS using in vivo neuroimaging and neurophysiology techniques. Progress on the genetic front has been less rapid. Proper diagnosis and education (involving the affected child and his or her parents, teachers, and peers) are essential prerequisites to the successful management of children with TS. When necessary, modestly effective antitic medications are available, although intervening to treat the comorbid attention-deficit/hyperactivity disorder and/or obsessive-compulsive disorder is usually the place to start.

CONCLUSIONS

Prospective longitudinal studies and randomized clinical trials have led to the refinement of several models of pathogenesis and advanced our evidence base regarding treatment options. However, fully explanatory models are needed that would allow for more accurate prognosis and the development of targeted and efficacious treatments.

Dopaminergic polymorphisms in Tourette syndrome: association with the DAT gene (SLC6A3)

Tourette syndrome (TS) is a chronic neuropsychiatric disorder characterized by involuntary motor and phonic tics. The pattern of inheritance and associated genetic abnormality has yet to be fully characterized. A dopaminergic abnormality in this disorder is supported by response to specific therapies, nuclear imaging, and postmortem studies. In this protocol, dopaminergic polymorphisms were examined for associations with TS and attention-deficit hyperactivity disorder (ADHD). Polymorphisms investigated included the dopamine transporter (DAT1 DdeI and DAT1 VNTR), dopamine receptor (D4 Upstream Repeat and D4 VNTR), dopamine converting enzyme (dopamine beta-hydroxylase), and the acid phosphatase locus 1 (ACP1) gene. DNA was obtained from 266 TS individuals +/- ADHD and 236 controls that were ethnicity-matched. A significant association, using a genotype-based association analysis, was identified for the TS-total and TS-only versus control groups for the DAT1 DdeI polymorphism (AG vs. AA, P = 0.004 and P = 0.01, respectively). Population structure, estimated by the genotyping of 27 informative SNP markers, identified 3 subgroups. A statistical re-evaluation of the DAT1 DdeI polymorphism following population stratification confirmed the association for the TS-total and TS-only groups, but the degree of significance was reduced (P = 0.017 and P = 0.016, respectively). This study has identified a significant association between the presence of TS and a DAT polymorphism. Since abnormalities of the dopamine transporter have been hypothesized in the pathophysiology of TS, it is possible that this could be a functional allele associated with clinical expression.

Tic disorders and ADHD: answers from a world-wide clinical dataset on Tourette syndrome

BACKGROUND

Tourette syndrome (TS) is a neurodevelopmental disorder with frequent comorbidity with Attention- deficit-Hyperactivity disorder (ADHD). The impact of this association is still a matter of debate.

METHOD

Using the TIC database containing 6,805 cases, the clinical differences were ascertained between subjects with and without ADHD.

RESULTS

The reported prevalence of ADHD in TS was 55%, within the range of many other reports. If the proband was diagnosed with ADHD, a family history of ADHD was much more likely. ADHD was associated with earlier diagnosis of TS and a much higher rate of anger control problems, sleep problems, specific learning disability, OCD, Oppositional-defiant disorder, mood disorder, social skill deficits, sexually inappropriate behaviour, and self-injurious behaviour. Subjects with seizures and with Developmental Coordination Disorder also had high rates of ADHD. Anxiety disorder, however, was not more frequent. Preliminary data suggest that most behavioural difficulties in ADHD are associated with the Combined or Hyperactive-Impulsive Subtypes of ADHD. Every large site (>200 cases) had a significantly increased rate of anger control problems in cases with ADHD.

CONCLUSION

Subjects with TS have high rates of ADHD and complex associations with other disorders. Clinically the findings confirm other research indicating the importance of ADHD in understanding the behavioural problems often associated with the diagnosis of TS. Additional ADHD comorbidity should be taken into account in diagnosis, management, and training.

Tic disorders in childhood

Despite our familiarity with tic disorders, their management remains challenging. The difficulty seldom relates to the diagnosis, which is usually based on the history, but rather in dealing with the impact of the tics and multiple comorbidities. The child and family must be educated and must be taught how to facilitate a positive attitude among others who come in contact with the patient. Knowledge and acceptance of the tics by other family members, peers, teachers, and coaches often become central to the child's well-being. Although many children can be managed without pharmacotherapy, medications are often central to achieving success. The goals of therapy and the appropriate choice of medication must be individualized. We are frequently challenged not only by the wide array of medication choices available but also by the decision of which symptom to treat first. The tics, despite being flamboyant, are often viewed by the child and family as less disabling than co-occurring conditions, such as attention-deficit hyperactivity disorder, obsessive-compulsiveness, or rage. Even when tics are the major issue, patients must define their goals for therapy. It is unreasonable to expect a complete resolution of tics and safety usually rules in favor of better tolerated but potentially less efficacious therapies. Developing strategies to minimize the lifelong impact of the multiple components of Tourette syndrome is an essential aspect of the care of these patients.

A controlled family study of attention-deficit/hyperactivity disorder and Tourette's disorder

OBJECTIVE

Although attention-deficit/hyperactivity disorder (ADHD) is frequently comorbid with Tourette's disorder (TD), it is unclear whether they have a common genetic etiology. Familial relationships between DSM-IV ADHD and TD are studied in TD+ADHD, TD-only (TD-ADHD), ADHD-only (ADHD-TD), and control groups.

METHOD

Case-control, direct-interview family study of 692 relatives of 75 TD+ADHD, 74 TD-only, 41 ADHD-only, and 49 control probands collected between 1999 and 2004. Age-corrected prevalence rates, odds ratios, and predictors of TD, ADHD, and OCD among relatives are estimated from blinded best-estimate diagnoses using survival Kaplan-Meier and generalized estimating equation regression analyses.

RESULTS

In relatives of the TD-only group, although ADHD exceeded control rates (p=.03), ADHD-TD (p=.51) rates were not increased. In the ADHD-only group, TD was increased (p=.004) but TD-ADHD rates were not increased (p=.18). Comorbid ADHD+TD diagnoses in relatives were elevated in all case groups (p<or=.03). TD in relatives predicted comorbid ADHD (p<.001), and ADHD in relatives predicted comorbid TD (p<.001). OCD in relatives predicted both ADHD (p=.002) and TD (p<.001) in relatives.

CONCLUSIONS

TD and ADHD are not alternate phenotypes of a single underlying genetic cause. There is an increased risk of comorbid ADHD and TD in affected families, possibly reflecting some overlapping neurobiology or pathophysiology.

Tourette syndrome: the self under siege

Tourette syndrome is a neurodevelopmental disorder characterized by motor and vocal tics--rapid, repetitive, stereotyped movements or vocalizations. Tourette syndrome typically has a prepubertal onset, and boys are more commonly affected than girls. Symptoms usually begin with transient bouts of simple motor tics. By age 10 years, most children are aware of nearly irresistible somatosensory urges that precede the tics. These urges likely reflect a defect in sensorimotor gating because they intrude into the child's conscious awareness and become a source of distraction and distress. A momentary sense of relief typically follows the completion of a tic. Over the course of hours, tics occur in bouts, with a regular intertic interval. Tics increase during periods of emotional excitement and fatigue. Tics can become "complex" in nature and appear to be purposeful. Tics can be willfully suppressed for brief intervals and can be evoked by the mere mention of them. Tics typically diminish during periods of goal-directed behavior, especially those that involve both heightened attention and fine motor or vocal control, as occur in musical and athletic performances. Over the course of months, tics wax and wane. New tics appear, often in response to new sources of somatosensory irritation, such as the appearance of a persistent vocal tic (a cough) following a cold. Over the course of years, tic severity typically peaks between 8 and 12 years of age. By the end of the second decade of life, many individuals are virtually tic free. Less than 20% of cases continue to experience clinically impairing tics as adults. Tics rarely occur in isolation, and other coexisting conditions--such as behavioral disinhibition, hypersensitivity to a broad range of sensory stimuli, problems with visual motor integration, procedural learning difficulties, attention-deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder, depression, anxiety, and emotional instability--are often a greater source of impairment than the tics themselves. Emerging behavioral treatments of Tourette syndrome are based in part on an understanding of the moment-to-moment experience of somatosensory urges and motor response. With identification of specific genes of major effect and advances in our understanding of the neural circuitry of sensorimotor gating, habit formation, and procedural memory--together with insights from postmortem brain studies, in vivo brain imaging, and electrophysiologic recordings--we might be on the threshold of a deeper understanding of the phenomenology and natural history of Tourette syndrome.

Tourette syndrome and chronic tics in a sample of children and adolescents

Forty-eight subjects with Tourette syndrome (M 36, F 12; mean age 11.2 years) and 48 with chronic tic disorder (M 33, F 15; mean age 12.1 years) were recruited in order to study the vertical transmission within families of a vulnerability to tic disorders or to other psychiatric disorders, the role of adverse pre- and perinatal events, and the presence of comorbid psychiatric conditions. As control group, 30 matched, psychiatrically unaffected subjects (M 20, F 10; mean age 10.8 years) were chosen. Screening measures included detailed anamnestic data, focused on family history of tics and other psychiatric disorders, prenatal events and birth. Subjects and parents were also questioned about psychiatric comorbidity. Group differences were compared using Fisher Test. Subjects with Tourette syndrome and those with chronic tic were similar to each other and different from controls in family history of tic disorders, pre- and perinatal events, and some comorbid psychiatric disorders (attention deficit hyperactivity disorder, sleep problems, and mood disorders). Tourette syndrome and chronic tic group were different in family history of obsessive-compulsive disorder and in comorbidity for obsessive-compulsive disorder and other anxiety disorders. Tourette syndrome and obsessive-compulsive disorder were significantly associated in this sample. These findings seem to indicate that Tourette syndrome and chronic tic disorder are part of the same disease entity, with Tourette syndrome being a more severe and complex form of tic disorder.

Clinical significance of tics and attention-deficit hyperactivity disorder (ADHD) in children with pervasive developmental disorder

The goal of this study was to examine the clinical significance of co-occurring tics and attention-deficit hyperactivity disorder (ADHD) as indicators of a more complex symptomatology in children with and without pervasive developmental disorder. Parents and teachers completed a Diagnostic and Statistical Manual of Mental Disorders-IV-referenced rating scale for 3- to 5- (n = 182/135) and 6- to 12- (n = 301/191) year-old children with pervasive developmental disorder and clinic controls, respectively. The percentage of children with tic behaviors varied with age: preschoolers (25%, 44%) versus elementary schoolchildren (60%, 66%) (parent and teacher ratings, respectively). For many psychiatric symptoms, screening prevalence rates were highest for the ADHD + tics group and lowest for the group with symptoms of neither, but the pattern of group differences varied by age group and informant. In general, there were few differences between the ADHD only and tics only groups. The pattern of ADHD/tic group differences was similar for both children with and without pervasive developmental disorder. We concluded that these findings support the notion that the co-occurrence of ADHD and tics is an indicator of a more complex psychiatric symptomatology in children with pervasive developmental disorder.

Co-existing disorders in ADHD -- implications for diagnosis and intervention

BACKGROUND

It is only recently that "comorbidity" in ADHD has come to the forefront as one of the most important aspects of the disorder. It is agreed that, often, these problems are at least as important as ADHD in contributing to the longer term outcome in the individual child.

OBJECTIVE

To provide the reader with basic information about clinics and treatment of "comorbidity" in ADHD.

METHOD

Review of the empirically based literature.

RESULTS

ADHD exists in a surprisingly high frequency together with a broad range of child neuropsychiatric disorders. This is accompanied with many still unresolved treatment problems.

CONCLUSION

It would not be appropriate to develop ADHD-services where clinicians would only have expertise in ADHD as such. Anyone working with children, adolescents and adults with ADHD would need to have training in general neuropsychiatry. Further research in this field is urgently needed.