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

Genome-Wide Association Study Points to Novel Locus for Gilles de la Tourette Syndrome

BACKGROUND

Tourette syndrome (TS) is a childhood-onset neurodevelopmental disorder of complex genetic architecture and is characterized by multiple motor tics and at least one vocal tic persisting for more than 1 year.

METHODS

We performed a genome-wide meta-analysis integrating a novel TS cohort with previously published data, resulting in a sample size of 6133 individuals with TS and 13,565 ancestry-matched control participants.

RESULTS

We identified a genome-wide significant locus on chromosome 5q15. Integration of expression quantitative trait locus, Hi-C (high-throughput chromosome conformation capture), and genome-wide association study data implicated the NR2F1 gene and associated long noncoding RNAs within the 5q15 locus. Heritability partitioning identified statistically significant enrichment in brain tissue histone marks, while polygenic risk scoring of brain volume data identified statistically significant associations with right and left thalamus volumes and right putamen volume.

CONCLUSIONS

Our work presents novel insights into the neurobiology of TS, thereby opening up new directions for future studies.

Hair Cortisol and Perceived Stress-Predictors for the Onset of Tics? A European Longitudinal Study on High-Risk Children

Some retrospective studies suggest that psychosocial stressors trigger the onset of tics. This study examined prospective hypothalamic-pituitary-adrenal (HPA) axis activity and perceived stress prior to tic onset. In the present study, 259 children at high risk for developing tics were assessed for hair cortisol concentration (HCC) and parent-on-child-reported perceived stress four-monthly over a three-year period. We used (i) generalised additive modelling (GAM) to investigate the time effects on HCC (hair samples n = 765) and perceived stress (questionnaires n = 1019) prior to tic onset and (ii) binary logistic regression to predict tic onset in a smaller subsample with at least three consecutive assessments (six to nine months before, two to five months before, and at tic onset). GAM results indicated a non-linear increasing course of HCC in children who developed tics, and a steady HCC course in those without tics, as well as a linear-increasing course of perceived stress in both groups. Logistic regression showed that with a higher HCC in hair samples collected in a range of two to five months before tic onset (which refers to cortisol exposure in a range of four to eight months), the relative likelihood of tic onset rose. Our study suggests increased stress prior to tic onset, as evidenced by higher HCC several months before tic onset.

Moderating Role of Depression on the Association of Tic Severity With Functional Impairment in Children

BACKGROUND

Chronic tic disorders (CTDs) commonly co-occur with other psychiatric disorders. CTDs have been linked to functional impairment and reduction in quality of life. Insufficient research is available on depressive symptoms in patients with CTD, especially children and adolescents, yielding conflicting findings. To investigate the presence of depressive symptoms in a cohort of children and young adolescents with CTD and to test whether they moderate the link between tic severity and functional impairment.

METHODS

The sample consisted of 85 children and adolescents (six to 18 years) with a CTD who were treated in a large referral center. Participants were evaluated using gold-standard self- and clinician-reporting instruments to measure tic symptom severity and tic-related functional impairment (Yale Global Tic Severity Scale), depression (Child Depression Inventory), and obsessive-compulsive symptoms (Children Yale Brown Obsessive Compulsive Scale).

RESULTS

Depressive symptoms (mild to severe) were exhibited by 21% of our sample. Study participants with CTD and comorbid obsessive-compulsive disorder (OCD) and/or attention-deficit/hyperactivity disorder had higher rates of depressive symptoms compared with those without comorbidities. Significant correlations were found within and among all tic-related and OCD-related measures, yet depressive symptoms only correlated to tic-related functional impairment. Depression significantly and positively moderated the correlation between tic severity and tic-related functional impairment.

CONCLUSIONS

Findings suggest that depression plays an important part as a moderator in the link between tic severity and functional impairment in children and adolescents. Our study highlights the importance of screening for and treating depression in patients with CTD.

Recent Advances in Genomics-Based Approaches for the Development of Intracellular Bacterial Pathogen Vaccines

Infectious diseases continue to be a leading cause of morbidity and mortality worldwide. The majority of infectious diseases are caused by intracellular pathogenic bacteria (IPB). Historically, conventional vaccination drives have helped control the pathogenesis of intracellular bacteria and the emergence of antimicrobial resistance, saving millions of lives. However, in light of various limitations, many diseases that involve IPB still do not have adequate vaccines. In response to increasing demand for novel vaccine development strategies, a new area of vaccine research emerged following the advent of genomics technology, which changed the paradigm of vaccine development by utilizing the complete genomic data of microorganisms against them. It became possible to identify genes related to disease virulence, genetic patterns linked to disease virulence, as well as the genetic components that supported immunity and favorable vaccine responses. Complete genomic databases, and advancements in transcriptomics, metabolomics, structural genomics, proteomics, immunomics, pan-genomics, synthetic genomics, and population biology have allowed researchers to identify potential vaccine candidates and predict their effects in patients. New vaccines have been created against diseases for which previously there were no vaccines available, and existing vaccines have been improved. This review highlights the key issues and explores the evolution of vaccines. The increasing volume of IPB genomic data, and their application in novel genome-based techniques for vaccine development, were also examined, along with their characteristics, and the opportunities and obstacles involved. Critically, the application of genomics technology has helped researchers rapidly select and evaluate candidate antigens. Novel vaccines capable of addressing the limitations associated with conventional vaccines have been developed and pressing healthcare issues are being addressed.

Tic disorders in children and adolescents: does the clinical presentation differ in males and females? A report by the EMTICS group

Tic disorders have a strong male predominance, with a male-to-female ratio of 4:1 in Tourette syndrome (TS) and 2:1 in persistent tic disorders. In other neurodevelopmental conditions, such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD), the disparity in sex distribution has been partially related to differences in symptom presentation between males and females. In tic disorders, however, little research has been conducted on this topic, probably due to the limited access to large samples with a significant proportion of females. The aim of this study was to describe sex differences in the clinical presentation of tic disorders in children and adolescents in one of the largest pediatric samples with TS/persistent tic disorders (n = 709, 23.3% females) recruited as part of the European Multicenter Tics in Children Study (EMTICS). Validated measures assessed the severity of tics and comorbid psychiatric symptoms. Using mixed-effect models, we found that sex had a significant influence on the severity of tics, ADHD symptoms, ASD symptoms, and emotional problems. Males had more severe symptoms than females, except for emotional problems. We also observed a statistically significant interaction between sex and age on the severity of tics and compulsions, with females showing higher symptom severity with increasing age than males. These findings indicate that the clinical presentation of TS/persistent tic disorders varies with sex. Males seem to exhibit a more noticeable pattern of clinical symptoms at a younger age that may contribute to their earlier detection in comparison to females.

Lifetime Prevalence, Predictors and Comorbidities of Tic Disorders: A Population-Based Survey of Children and Adolescents in Iran

In this population-based survey, we have evaluated the lifetime prevalence of tic disorders and related sociodemographic factors and comorbidities of them. The data obtained from face-to-face interviews with 29,885 children and adolescents aged 6-18 years. We used the multistage cluster sampling method and a cross-sectional design. Tic disorders and other psychiatric disorders were assessed using the Persian version of the Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL). The lifetime prevalence of tic disorders was 1.5% (95% CI  (1.3-1.7%)). The highest prevalence was in the age range of 15-18 years old with 1.9% (95% CI  (1.6-2.3%)).57.7% (95% CI 51.8-63.3%) of patients with tic disorders had comorbidity with other psychiatric disorders. Increasing the prevalence of tic disorder with increasing age among Iranian children and adolescents, emphasizes the need to pay more attention to use of pharmacological and non-pharmacological treatments and increase education to families in this regard.

Tic disorders and premonitory urges: validation of the Spanish-language version of the Premonitory Urge for Tics Scale in children and adolescents

INTRODUCTION

Most people with persistent tics report an unpleasant sensation (premonitory urge) before the tic. In recent years, interest in these sensory phenomena has increased due to their important role in behavioural therapy. However, instruments for assessing these sensations remain scarce. Among the available instruments, the Premonitory Urge for Tics Scale (PUTS) is the most widely used.

METHODS

We examined the psychometric properties and factor structure of the Spanish-language version of the PUTS in a sample of 72 children and adolescents with Tourette syndrome or persistent tic disorders. We analysed data from the total sample and by age group (children up to 10 years old and children/adolescents over 10).

RESULTS

The PUTS presented good internal consistency and moderate correlations between items on the scale (except for item 1). Divergent validity was good, test-retest reliability was adequate, and a bifactorial structure was identified (one dimension related to mental phenomena reported in obsessive-compulsive disorder, and another related to the quality and frequency of premonitory urges). These results were replicated in both age groups, with lower divergent validity and test-retest reliability in the younger group.

CONCLUSIONS

The Spanish-language version of the PUTS is a valid, reliable tool for assessing premonitory urges in both children and adolescents, especially after the age of 10.

Clinical precursors of tics: an EMTICS study

BACKGROUND

Children with Tourette syndrome (TS) often have comorbid disorders, particularly attention-deficit/hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). While subtle premorbid symptoms have been described in various psychiatric disorders, the presence of clinical precursors that may exist before the onset of tics is unknown. This longitudinal study aimed to find clinical precursors of tics by assessing a range of clinical characteristics prior to tic onset in comparison with children without onset of tics.

METHODS

A sample of 187 3- to 10-year-old first-degree unaffected relatives of children with TS were followed up to 7 years in the European Multicentre Tics in Children Study (EMTICS). We investigated whether clinical characteristics assessed at baseline predicted tic onset, comparing 126 children without tic onset to 61 children who developed tics. We used the least absolute shrinkage and selection operator (LASSO) method, a penalised logistic regression approach. We also explored sex differences and repeated our analyses in an age- and sex-matched subsample.

RESULTS

Children with tic onset were more frequently male (β = -0.36), had higher baseline severity of conduct problems (β = 0.23), autism spectrum disorder symptoms (ASD; β = 0.08), compulsions (β = 0.02) and emotional problems (β = 0.03) compared to children without tic onset. Conduct and ASD problems were male-specific predictors, whereas severity of compulsions and oppositional (β = 0.39) and emotional problems were female-specific predictors.

CONCLUSION

This study supports the presence of clinical precursors prior to tic onset and highlights the need of sex-specific monitoring of children at risk of developing tics. This may aid in the earlier detection of tics, particularly in females. We moreover found that tics most often persisted one year after tic onset, in contrast to the common belief that tics are mostly transient.

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.

Changes of Cytokines in Children With Tic Disorder

Tic disorder (TD) is a common childhood-onset disease associated with abnormal development of brain networks involved in the motor and sensory processing. The underlying pathophysiological mechanisms in TD are still unclear. An involvement of immune mechanisms in its pathophysiology has been proposed. This study investigates the association between the changes of cytokines and the etiology and development of TD. Different expressions of cytokines in a larger number of samples in our study may provide new insights to the field. The levels of cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ) were evaluated in 1,724 patients who were clinically diagnosed with TD from 1 to 17.5 years old and 550 were from 6 months to 14.5 years old in the control group. We assessed the levels of cytokines according to the patient's medication status and the severity of the disease. Of the cytokines we investigated, the serum IL-6 concentration of children with TD was significantly higher than that of the control group, while the levels of other cytokines were lower in TD patients. In the patient group whose YTGSS score ranged from 1 to 9, the IL-4, IL-10, and IFN-γ levels increased in medication group compared to unmedication group. Our data suggested that the cytokines (IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ) may play an important role in the etiology and the severity in TD. Whether drug intervention in the early stage of tic disorder has a better effect on children needs further research.

Tourettic OCD: Current understanding and treatment challenges of a unique endophenotype

Obsessive compulsive disorder (OCD) and chronic tic disorders (CTD) including Tourette Syndrome (TS) are often comorbid conditions. While some patients present with distinct symptoms of CTD and/or OCD, a subset of patients demonstrate a unique overlap of symptoms, known as Tourettic OCD (TOCD), in which tics, compulsions, and their preceding premonitory urges are overlapping and tightly intertwined. The specific behaviors seen in TOCD are typically complex tic-like behaviors although with a compulsive and partially anxious nature reminiscent of OCD. TOCD is not classified within the Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-5) as an independent diagnostic entity, but mounting evidence suggests that TOCD is an intermediate neuropsychiatric disorder distinct from either TS or OCD alone and as such represents a unique phenomenology. In this review of TOCD we discuss clinical, genetic, environmental, neurodevelopmental, and neurocircuit-based research to better characterize our current understanding of this disorder. TOCD is characterized by earlier age of onset, male predominance, and specific symptom clusters such as lower tendency toward compulsions related to checking, cleaning, and reassurance seeking and higher tendency toward compulsions such as rubbing, tapping, or touching associated with symmetry concerns or thoughts of exactness. Functional magnetic resonance imaging (fMRI) imaging suggests that TOCD symptoms may arise from involvement of an intermediate neurocircuitry distinct from classic OCD or classic CTD. Small cumulative contributions from multiple genetic loci have been implicated, as have environmental factors such as infection and perinatal trauma. In addition, this review addresses the treatment of TOCD which is especially complex and often treatment resistant and requires pharmacology and behavioral therapy in multiple modalities. Given the distressing impact of TOCD on patients' functioning, the goal of this review is to raise awareness of this distinct entity toward the goal of improving standards of care.

Hair cortisol-a stress marker in children and adolescents with chronic tic disorders? A large European cross-sectional study

BACKGROUND

There is clear evidence that tic disorders (TDs) are associated with psychosocial stress as well as emotional and behavioral problems. Studies have shown that individuals with TDs have higher acute physiological stress responses to external, single stressors (as reflected by saliva cortisol). The aim of the present study was to examine a physiological marker of longer-term stress (as reflected by hair cortisol concentration) in children and adolescents with TDs and unaffected siblings of individuals with TDs.

METHODS

Two samples of a European cohort were included in this study. In the COURSE sample, 412 children and adolescents aged 3-16 years with a chronic TD including Tourette syndrome according to DSM IV-TR criteria were included. The ONSET sample included 131 3-10 years old siblings of individuals with TDs, who themselves had no tics. Differences in hair cortisol concentration (HCC) between the two samples were examined. Within the COURSE sample, relations of HCC with tic severity and perceived psychosocial stress as well as potential effects and interaction effects of comorbid emotional and behavioral problems and psychotropic medication on HCC were investigated.

RESULTS

There were no differences in HCC between the two samples. In participants with TDs, there were no associations between HCC and tic severity or perceived psychosocial stress. No main effects of sex, psychotropic medication status and comorbid emotional and behavioral problems on HCC were found in participants with TDs.

CONCLUSION

A link between HCC and TDs is not supported by the present results.

Vitamin D levels in children and adolescents with chronic tic disorders: a multicentre study

This study investigated whether vitamin D is associated with the presence or severity of chronic tic disorders and their psychiatric comorbidities. This cross-sectional study compared serum 25-hydroxyvitamin D [25(OH)D] (ng/ml) levels among three groups: children and adolescents (3-16 years) with CTD (n = 327); first-degree relatives (3-10 years) of individuals with CTD who were assessed for a period of up to 7 years for possible onset of tics and developed tics within this period (n = 31); and first-degree relatives who did not develop tics and were ≥ 10 years old at their last assessment (n = 93). The relationship between 25(OH)D and the presence and severity of tics, as well as comorbid obsessive-compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD), were analysed controlling for age, sex, season, centre, latitude, family relatedness, and comorbidities. When comparing the CTD cohort to the unaffected cohort, the observed result was contrary to the one expected: a 10 ng/ml increase in 25(OH)D was associated with higher odds of having CTD (OR 2.08, 95% CI 1.27-3.42, p < 0.01). There was no association between 25(OH)D and tic severity. However, a 10 ng/ml increase in 25(OH)D was associated with lower odds of having comorbid ADHD within the CTD cohort (OR 0.55, 95% CI 0.36-0.84, p = 0.01) and was inversely associated with ADHD symptom severity (β = - 2.52, 95% CI - 4.16-0.88, p < 0.01). In conclusion, lower vitamin D levels were not associated with a higher presence or severity of tics but were associated with the presence and severity of comorbid ADHD in children and adolescents with CTD.

Mycoplasma pneumoniae IgG positivity is associated with tic severity in chronic tic disorders

Infectious pathogens may represent an environmental risk factor for chronic tic disorders (CTD). This cross-sectional study aimed to determine whether Mycoplasma pneumoniae (M. pneumoniae) IgG positivity is associated with the presence or severity of tics. We compared M. pneumoniae IgG positivity across three groups: children and adolescents (3-16 years) with CTD (CTD group; n = 302); siblings (3-10 years) of people with CTD who developed tics within a seven-year follow-up period (tic onset group; n = 51); siblings (4-10 years) who did not develop tics within the study period and were ≥10-years-old at their last assessment (unaffected group; n = 88). The relationship between M. pneumoniae IgG positivity and the presence and severity of tics was analysed using multilevel models controlling for site, family relatedness, sex, age, presence of comorbid obsessive-compulsive and/or attention-deficit/hyperactivity disorder and use of psychotropic medication. M. pneumoniae IgG positivity was not associated with the presence of CTD, or the first onset of tics as compared to siblings who remained unaffected. M. pneumoniae IgG positivity was associated with a higher tic severity score within the CTD group (β = 2.64, s.e. = 1.15, p = 0.02). It is possible that M. pneumoniae infection influences tic severity in CTD or, that having more severe tics, increases the risk of infection. However, it is more likely that the association observed in this study reflects a propensity toward enhanced immune responses in people with CTD and that, rather than a causal relationship, infection and greater tic severity are indirectly linked via shared underlying immune mechanisms.

Emotion regulation and tic disorders in children

Tic disorders (TD) are developmental neuropsychiatric conditions often accompanied by comorbid conditions, and psychosocial hardships for child and family. The etiology of tics is unknown, and is complex and multifactorial. Stress is known to aggravate tic expression as well as associated comorbidities. Consequently, this study focused on possible connections between stress, emotion regulation, tic expression, and related psychopathology. Sixty consecutive admissions were assessed for perceived stress, emotional dysregulation, severity of obsessions and compulsions, anxiety, depression, attention deficit disorder, and tic expression at a TD clinic, in a university affiliated pediatric hospital. The results indicated that stress and emotion dysregulation were significantly related to both tic expression and severity of comorbidities. We discuss the role of emotion regulation dimensions regarding TD and related psychopathology as well as the mediating role of emotion regulation, and how they may contribute to the development of improved therapies for children with TD.

Recent progress on Tourette syndrome

Tic disorders and Tourette syndrome are the most common movement disorders in children and are characterized by movements or vocalizations. Clinically, Tourette syndrome is frequently associated with comorbid psychiatric symptoms. Although dysfunction of cortical–striatal–thalamic–cortical circuits with aberrant neurotransmitter function has been considered the proximate cause of tics, the mechanism underlying this association is unclear. Recently, many studies have been conducted to elucidate the epidemiology, clinical course, comorbid symptoms, and pathophysiology of tic disorders by using laboratory studies, neuroimaging, electrophysiological testing, environmental exposure, and genetic testing. In addition, many researchers have focused on treatment for tics, including behavioral therapy, pharmacological treatment, and surgical treatment. Here, we provide an overview of recent progress on Tourette syndrome.

Immunity and Gilles de la Tourette syndrome: A systematic review and meta-analysis of evidence for immune implications in Tourette syndrome

BACKGROUND AND PURPOSE

The neurobiology of Gilles de la Tourette syndrome (GTS) is known to involve corticostriatal loops possibly under genetic control. Less is known about possible environmental triggers of GTS. Specifically, immune-related events following possible environmental inducers have been evoked, but important controversies still exist. In this systematic review and meta-analysis, we looked for evidence in favor of such possibilities.

METHODS

We performed a systematic review and meta-analysis of all immunological data in PubMed.

RESULTS

We found large discrepancies concerning immune dysfunctions in GTS, and meta-analyzing cytokines data did not allow us to conclude there is an involvement of specific cytokines in GTS neurobiology. When looking specifically at pediatric autoimmune neuropsychiatric disorder associated with streptococcus/pediatric acute onset neuropsychiatric syndrome, we found some important evidence of a possible infectious involvement but in a limited number of studies. Our meta-analysis found an increased level of anti-streptolysin O antibodies in GTS patients, but the level of anti-DNase B antibodies was not increased.

CONCLUSIONS

Too many questions still exist to allow us to definitively reach the conclusion that there is an infectious and immunological etiology in GTS. Much work is still needed to elucidate the possible role of immunology in GTS neurobiology and to favor immunological treatment rather than classical treatment.

A Comprehensive Review of Tic Disorders in Children

Tics are characterized by sudden, rapid, recurrent, nonrhythmic movement or vocalization, and are the most common movement disorders in children. Their onset is usually in childhood and tics often will diminish within one year. However, some of the tics can persist and cause various problems such as social embarrassment, physical discomfort, or emotional impairments, which could interfere with daily activities and school performance. Furthermore, tic disorders are frequently associated with comorbid neuropsychiatric symptoms, which can become more problematic than tic symptoms. Unfortunately, misunderstanding and misconceptions of tic disorders still exist among the general population. Understanding tic disorders and their comorbidities is important to deliver appropriate care to patients with tics. Several studies have been conducted to elucidate the clinical course, epidemiology, and pathophysiology of tics, but they are still not well understood. This article aims to provide an overview about tics and tic disorders, and recent findings on tic disorders including history, definition, diagnosis, epidemiology, etiology, diagnostic approach, comorbidities, treatment and management, and differential diagnosis.

Networks in the Field of Tourette Syndrome

Gilles de la Tourette syndrome (TS) is a neuropsychiatric neurodevelopmental disorder with the cardinal clinical features of motor and phonic tics. Clinical phenomenology can be complex since, besides tics, there are other features including premonitory urges preceding tics, pali-, echo-, and coprophenomena, hypersensitivity to external stimuli, and symptom dependency on stress, attention, and other less well-defined factors. Also, the rate of comorbidities, particularly attention deficit hyperactivity disorder and obsessive-compulsive disorder, is high. Mirroring the complexities of the clinical course and phenomenology, pathophysiological findings are very diverse, and etiology is disputed. It has become clear, though, that abnormalities in the basal ganglia and their connections with cortical areas are key for the understanding of the pathophysiology and as regards etiology, genetic factors are crucial. Against this background, both adequate clinical management of TS and TS-related research require multidisciplinary preferably international cooperation in larger groups or networks to address the multiple facets of this disorder and yield valid and useful data. In particular, large numbers of patients are needed for brain imaging and genetic studies. To meet these requirements, a number of networks and groups in the field of TS have developed over the years creating an efficient, lively, and supportive international research community. In this review, we will provide an overview of these groups and networks.

Potential impact of COVID-19 on ongoing clinical trials: a simulation study with the neurological Yale Global Tic Severity Scale based on the CANNA-TICS study

The COVID‐19 pandemic has manifold impacts on clinical trials. In response, drug regulatory agencies and public health bodies have issued guidance on how to assess potential impacts on ongoing clinical trials and stress the importance of a risk‐assessment as a pre‐requisite for modifications to the clinical trial conduct. This article presents a simulation study to assess the impact on the power of an ongoing clinical trial without the need to unblind trial data and compromise trial integrity. In the context of the CANNA‐TICS trial, investigating the effect of nabiximols on reducing the total tic score of the Yale Global Tic Severity Scale (YGTSS‐TTS) in patients with chronic tic disorders and Tourette syndrome, the impact of the two COVID‐19 related intercurrent events handled by a treatment policy strategy is investigated using a multiplicative and additive data generating model. The empirical power is examined for the analysis of the YGTSS‐TTS as a continuous and dichotomized endpoint using analysis techniques adjusted and unadjusted for the occurrence of the intercurrent event. In the investigated scenarios, the simulation studies showed that substantial power losses are possible, potentially making sample size increases necessary to retain sufficient power. However, we were also able to identify scenarios with only limited loss of power. By adjusting for the occurrence of the intercurrent event, the power loss could be diminished to different degrees in most scenarios. In summary, the presented risk assessment approach may support decisions on trial modifications like sample size increases, while maintaining trial integrity.

Association of Group A Streptococcus Exposure and Exacerbations of Chronic Tic Disorders: A Multinational Prospective Cohort Study

OBJECTIVE

To examine prospectively the association between group A Streptococcus (GAS) pharyngeal exposures and exacerbations of tics in a large multicenter population of youth with chronic tic disorders (CTD) across Europe.

METHODS

We followed up 715 children with CTD (age 10.7 ± 2.8 years, 76.8% boys), recruited by 16 specialist clinics from 9 countries, and followed up for 16 months on average. Tic, obsessive-compulsive symptom (OCS), and attention-deficit/hyperactivity disorder (ADHD) severity was assessed during 4-monthly study visits and telephone interviews. GAS exposures were analyzed using 4 possible combinations of measures based on pharyngeal swab and serologic testing. The associations between GAS exposures and tic exacerbations or changes of tic, OC, and ADHD symptom severity were measured, respectively, using multivariate logistic regression plus multiple failure time analyses and mixed effects linear regression.

RESULTS

A total of 405 exacerbations occurred in 308 of 715 (43%) participants. The proportion of exacerbations temporally associated with GAS exposure ranged from 5.5% to 12.9%, depending on GAS exposure definition. We did not detect any significant association of any of the 4 GAS exposure definitions with tic exacerbations (odds ratios ranging between 1.006 and 1.235, all p values >0.3). GAS exposures were associated with longitudinal changes of hyperactivity-impulsivity symptom severity ranging from 17% to 21%, depending on GAS exposure definition.

CONCLUSIONS

This study does not support GAS exposures as contributing factors for tic exacerbations in children with CTD. Specific workup or active management of GAS infections is unlikely to help modify the course of tics in CTD and is therefore not recommended.

Yale Global Tic Severity Scale (YGTSS): Psychometric Quality of the Gold Standard for Tic Assessment Based on the Large-Scale EMTICS Study

The Yale Global Tic Severity Scale (YGTSS) is a clinician-rated instrument considered as the gold standard for assessing tics in patients with Tourette's Syndrome and other tic disorders. Previous psychometric investigations of the YGTSS exhibit different limitations such as small sample sizes and insufficient methods. To overcome these shortcomings, we used a subsample of the large-scale "European Multicentre Tics in Children Study" (EMTICS) including 706 children and adolescents with a chronic tic disorder and investigated convergent, discriminant and factorial validity, as well as internal consistency of the YGTSS. Our results confirm acceptable convergent and good to very good discriminant validity, respectively, indicated by a sufficiently high correlation of the YGTSS total tic score with the Clinical Global Impression Scale for tics (r _s = 0.65) and only low to medium correlations with clinical severity ratings of attention deficit/hyperactivity symptoms (r _s = 0.24), obsessive-compulsive symptoms (r _s = 27) as well as internalizing symptoms (r _s = 0.27). Internal consistency was found to be acceptable (Ω = 0.58 for YGTSS total tic score). A confirmatory factor analysis supports the concept of the two factors "motor tics" and "phonic tics," but still demonstrated just a marginal model fit (root mean square error of approximation = 0.09 [0.08; 0.10], comparative fit index = 0.90, and Tucker Lewis index = 0.87). A subsequent analysis of local misspecifications revealed correlated measurement errors, suggesting opportunities for improvement regarding the item wording. In conclusion, our results indicate acceptable psychometric quality of the YGTSS. However, taking the wide use and importance of the YGTSS into account, our results suggest the need for further investigations and improvements of the YGTSS. In addition, our results show limitations of the global severity score as a sum score indicating that the separate use of the total tic score and the impairment rating is more beneficial.

Tic disorders and premonitory urges: validation of the Spanish-language version of the Premonitory Urge for Tics Scale in children and adolescents

INTRODUCTION

Most people with persistent tics report an unpleasant sensation (premonitory urge) before the tic. In recent years, interest in these sensory phenomena has increased due to their important role in behavioural therapy. However, instruments for assessing these sensations remain scarce. Among the available instruments, the Premonitory Urge for Tics Scale (PUTS) is the most widely used.

METHODS

We examined the psychometric properties and factor structure of the Spanish-language version of the PUTS in a sample of 72 children and adolescents with Tourette syndrome or persistent tic disorders. We analysed data from the total sample and by age group (children up to 10 years old and children/adolescents over 10).

RESULTS

The PUTS presented good internal consistency and moderate correlations between items on the scale (except for item one). Divergent validity was good, test-retest reliability was adequate, and a bifactorial structure was identified (one dimension related to mental phenomena reported in obsessive-compulsive disorder, and another related to the quality and frequency of premonitory urges). These results were replicated in both age groups, with lower divergent validity and test-retest reliability in the younger group.

CONCLUSIONS

The Spanish-language version of the PUTS is a valid, reliable tool for assessing premonitory urges in both children and adolescents, especially after the age of 10.

General health and mortality in Tourette syndrome and chronic tic disorder: A mini-review

Current knowledge on the general somatic health and causes of death in Tourette syndrome and chronic tic disorder is very limited. Here, we review the available literature on the topic, while highlighting strengths and weaknesses of the studies conducted to date. These previous works have suggested associations between Tourette syndrome and chronic tic disorder and a range of health conditions, including autoimmune disorders, common allergies and respiratory diseases, sleep difficulties, and metabolic and cardiovascular outcomes. Additionally, the risk of mortality in tic disorders might be higher than that of the general population, but specific causes of death have rarely been studied, except for substance use-related deaths and suicide, which are significantly higher in individuals with Tourette syndrome and chronic tic disorder. Many of these emerging findings require replication and extension but, taken together, they suggest that that it might be sensible to monitor the general health and suicide risk of individuals with Tourette syndrome or chronic tic disorder across the lifespan. We suggest further avenues for research on this topic.

Anti-dopamine D2 receptor antibodies in chronic tic disorders

AIM

To investigate the association between circulating anti-dopamine D2 receptor (D2R) autoantibodies and the exacerbation of tics in children with chronic tic disorders (CTDs).

METHOD

One hundred and thirty-seven children with CTDs (108 males, 29 females; mean age [SD] 10y 0mo [2y 7mo], range 4-16y) were recruited over 18 months. Patients were assessed at baseline, at tic exacerbation, and at 2 months after exacerbation. Serum anti-D2R antibodies were evaluated using a cell-based assay and blinded immunofluorescence microscopy scoring was performed by two raters. The association between visit type and presence of anti-D2R antibodies was measured with McNemar's test and repeated-measure logistic regression models, adjusting for potential demographic and clinical confounders.

RESULTS

At exacerbation, 11 (8%) participants became anti-D2R-positive ('early peri-exacerbation seroconverters'), and nine (6.6%) became anti-D2R-positive at post-exacerbation ('late peri-exacerbation seroconverters'). The anti-D2R antibodies were significantly associated with exacerbations when compared to baseline (McNemar's odds ratio=11, p=0.003) and conditional logistic regression confirmed this association (Z=3.49, p<0.001) after adjustment for demographic and clinical data and use of psychotropic drugs.

INTERPRETATION

There is a potential association between immune mechanisms and the severity course of tics in adolescents with CTDs.

Intravenous Immunoglobulin Treatment Did Not Improve Tics in a Patient With Gilles de la Tourette Syndrome and Intrathecal Antibody Synthesis

Gilles de la Tourette syndrome (GTS) is a neuropsychiatric disorder characterized by motor and vocal tics. There are several hypotheses as to the cause of the disease. One of which suggests that the immune system is involved in the pathophysiology of GTS. Here, we present a 40-year-old female patient with a typical history and clinical presentation of GTS with tics and psychiatric comorbidities, in whom positive oligoclonal bands (OCBs) type 2 in cerebral spinal fluid (CSF) were detected in an earlier study. At that time point, all other investigations were unremarkable (including neurological examination and cMRI), but 2 years later, she presented with further neurological symptoms including tetraparesis mostly affecting the left limbs, distal hypesthesia and paresthesia, and dyspnea. Since further examinations (including EMG, MRI, CSF, virological, and bacteriological tests, as well as autoimmune-encephalitis antibodies) revealed normal results, based on clinical presentation, the diagnosis of Guillain-Barré-like immune-mediated neuropathy was made and treatment with intravenous immunoglobulins (IVIg) (30 g/day for 5 days) was initiated resulting in complete remission of immune-mediated neuropathy. Based on the “immune hypothesis” of GTS, we were interested in whether in this patient positive CSF OCBs might serve as a biomarker for treatment response of tics and additional GTS-related psychiatric symptoms to IVIg, and therefore assessed tics, premonitory urges, and psychiatric comorbidities before and several times after the IVIg treatment. However, even though immune-mediated neuropathy resolved after treatment, tics, premonitory urges, and comorbidities remained unchanged. Thus, this case study suggests that treatment with IVIg is not effective in the treatment of GTS—even in a patient with intrathecal antibody synthesis as expressed by CSF isolated OCBs.

The Premonitory Urge for Tics Scale in a large sample of children and adolescents: psychometric properties in a developmental context. An EMTICS study

Premonitory urges are uncomfortable physical sensations preceding tics that occur in most individuals with a chronic tic disorder. The Premonitory Urge for Tics Scale (PUTS) is the most frequently used self-report measure to assess the severity of premonitory urges. We aimed to evaluate the psychometric properties of the PUTS in the largest sample size to date (n = 656), in children aged 3-16 years, from the baseline measurement of the longitudinal European Multicenter Tics in Children Study (EMTICS). Our psychometric evaluation was done in three age-groups: children aged 3-7 years (n = 103), children between 8 and 10 years (n = 253), and children aged 11-16 years (n = 300). The PUTS exhibited good internal reliability in children and adolescents, also under the age of 10, which is younger than previously thought. We observed significant but small correlations between the severity of urges and severity of tics and obsessive-compulsive symptoms, and between severity of urges and ratings of attention-deficit/hyperactivity disorder and internalizing and externalizing behaviors, however, only in children of 8-10 years. Consistent with previous results, the 10th item of the PUTS correlated less with the rest of the scale compared to the other items and, therefore, should not be used as part of the questionnaire. We found a two-factor structure of the PUTS in children of 11 years and older, distinguishing between sensory phenomena related to tics, and mental phenomena as often found in obsessive-compulsive disorder. The age-related differences observed in this study may indicate the need for the development of an age-specific questionnaire to assess premonitory urges.

Immunity in Gilles de la Tourette-Syndrome: Results From a Cerebrospinal Fluid Study

Background: Several lines of evidence support the hypothesis of an autoimmune origin of Gilles de la Tourette-Syndrome (GTS). Accordingly, in a recent study we detected positive oligoclonal bands (OCB) in cerebrospinal fluid (CSF) in >30% of adult patients indicating an intrathecal antibody synthesis. However, until today no corresponding antibodies could be identified. The aims of this study were to replicate our findings of positive OCB in an independent sample and to detect CSF autoantibodies.

Methods: In this prospective study, 20 adult patients with GTS (male: female = 18:2, median age 36.1 years ± 14.34 SD) were included. All patients were thoroughly clinically characterized. Magnetic Resonance Imaging (MRI) and CSF standard measurements were performed. Isoelectric focusing on polyacrylamide gels with silver staining was used to detect OCB. To examine specific and unspecified autoantibodies, we used transfected Human Embryonic Kidney (HEK) cells expressing different surface antigens (NMDA-, CASPR2-, LGI1-, AMPA-, or GABAB1/B), indirect immunofluorescence on different brain tissue sections, and enzyme-linked visualization. Additionally, we differentiated Glioma stem cells SY5Y (human neuroblastoma) using retinoic acid and astrocytes (rat).

Results: CSF analyses showed positive OCB (type 2) in 4/20 patients (20%). Using transfected HEK cells we did not find specific surface-autoantibodies. Immunohistochemistry on tissue-sections, SY5Y Glioma stem-cells, and astrocytes showed no specific binding patterns either.

Conclusions: Our results corroborate previous findings and demonstrate positive OCB in a substantial number of patients with GTS (prevalence in healthy controls: 5%). Although this is the largest study investigating CSF autoantibodies in GTS using several techniques, we failed to detect any specific or unspecified autoantibodies.

Early intervention for obsessive compulsive disorder: An expert consensus statement

Obsessive-compulsive disorder (OCD) is common, emerges early in life and tends to run a chronic, impairing course. Despite the availability of effective treatments, the duration of untreated illness (DUI) is high (up to around 10 years in adults) and is associated with considerable suffering for the individual and their families. This consensus statement represents the views of an international group of expert clinicians, including child and adult psychiatrists, psychologists and neuroscientists, working both in high and low and middle income countries, as well as those with the experience of living with OCD. The statement draws together evidence from epidemiological, clinical, health economic and brain imaging studies documenting the negative impact associated with treatment delay on clinical outcomes, and supporting the importance of early clinical intervention. It draws parallels between OCD and other disorders for which early intervention is recognized as beneficial, such as psychotic disorders and impulsive-compulsive disorders associated with problematic usage of the Internet, for which early intervention may prevent the development of later addictive disorders. It also generates new heuristics for exploring the brain-based mechanisms moderating the 'toxic' effect of an extended DUI in OCD. The statement concludes that there is a global unmet need for early intervention services for OC related disorders to reduce the unnecessary suffering and costly disability associated with under-treatment. New clinical staging models for OCD that may be used to facilitate primary, secondary and tertiary prevention within this context are proposed.