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

Immp2l knockdown in male mice increases stimulus-driven instrumental behaviour but does not alter goal-directed learning or neuron density in cortico-striatal circuits in a model of Tourette syndrome and autism spectrum disorder

Cortico-striatal neurocircuits mediate goal-directed and habitual actions which are necessary for adaptive behaviour. It has recently been proposed that some of the core symptoms of autism spectrum disorder (ASD) and Gilles de la Tourette syndrome (GTS), such as tics and other repetitive behaviours, may emerge because of imbalances in these neurocircuits. We have recently developed a model of ASD and GTS by knocking down Immp2l, a mitochondrial gene frequently associated with these disorders. The current study sought to determine whether Immp2l knockdown (KD) in male mice alters flexible, goal- or cue- driven behaviour using procedures specifically designed to examine response-outcome and stimulus-response associations, which underlie goal-directed and habitual behaviour, respectively. Whether Immp2l KD alters neuron density in cortico-striatal neurocircuits known to regulate these behaviours was also examined. Immp2l KD mice and wild type-like mice (WT) were trained on Pavlovian and instrumental learning procedures where auditory cues predicted food delivery and lever-press responses earned a food outcome. It was demonstrated that goal-directed learning was not changed for Immp2l KD mice compared to WT mice, as lever-press responses were sensitive to changes in the value of the food outcome, and to contingency reversal and degradation. There was also no difference in the capacity of KD mice to form habitual behaviours compared to WT mice following extending training of the instrumental action. However, Immp2l KD mice were more responsive to auditory stimuli paired with food as indicated by a non-specific increase in lever response rates during Pavlovian-to-instrumental transfer. Finally, there were no alterations to neuron density in striatum or any prefrontal cortex or limbic brain structures examined. Thus, the current study suggests that Immp2l is not necessary for learned maladaptive goal or stimulus driven behaviours in ASD or GTS, but that it may contribute to increased capacity for external stimuli to drive behaviour. Alterations to stimulus-driven behaviour could potentially influence the expression of tics and repetitive behaviours, suggesting that genetic alterations to Immp2l may contribute to these core symptoms in ASD and GTS. Given that this is the first application of this battery of instrumental learning procedures to a mouse model of ASD or GTS, it is an important initial step in determining the contribution of known risk-genes to goal-directed versus habitual behaviours, which should be more broadly applied to other rodent models of ASD and GTS in the future.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Assessment of Knowledge about Tourette’s Syndrome among Medical Students and Primary Physicians in Riyadh, Saudi Arabia: A Cross-Sectional Study

Background. Tourette’s syndrome (TS), a chronic, often disabling neuropsychiatric disorder characterized by motor and vocal tics, is frequently misdiagnosed, or patients are delayed in diagnosis. There is severe deficiency of research about Tourette’s syndrome (TS) in the Middle East region. Objectives. To evaluate the knowledge and attitude of medical students and primary care physicians (PCPs) about TS and tic disorders. Methods. IRB approved, cross-sectional study. A total of 316 medical students of King Saud bin Abdulaziz University and 59 primary care physicians of Riyadh participated. Convenient, cluster sampling was used. A validated, self-administered questionnaire was used. Sum of all knowledge questions was calculated. Data were analyzed using SPSS software. Results. Survey was completed by 375 students and physicians, of whom 253 (67.5%) were men. Mean general knowledge score was 61.5 (±12.04) out of 100. Majority (66.1%) knew the diagnostic criteria for TS; only 46.1% considered antipsychotics as effective treatment. Only 25.1% had ever heard of habit reversal; 70% wanted to learn more. Only 10% of physicians had treated a patient with TS. There was no difference in knowledge between men and women ( $p=0.776$ ). Board-certified physicians had a higher knowledge score ( $p<0.05$ ). Family physicians demonstrated higher level of knowledge compared to other physicians ( $p<0.05$ ). There was no difference between knowledge of students of different years ( $p=0.859$ ) or between students and physicians ( $p=0.569$ ). Conclusion. There was alarming lack of knowledge about Tourette syndrome at various level of medical training and practice including students and physicians. Those who achieved board certification and practiced as family physicians fared better in knowledge about Tourette’s syndrome.

A comparison of food avoidant behaviours and sensory sensitivity in adults with and without Tourette syndrome

Food selectivity has been shown to be more persistent and severe in children with Tourette syndrome (TS) compared to their typically developing peers. The current study aimed to examine differences in food selectivity, food neophobia and Avoidant Restrictive Food Intake Disorder (ARFID)-associated behaviours, between adults with and without TS. Fifty-three adults diagnosed with TS were compared to 53 neurotypical adults and completed the following measures online: Adult Eating Behaviour Questionnaire (AEBQ), Nine-Item Avoidant/Restrictive Food Intake disorder screen (NIAS), Food Neophobia Scale (FNS) and the Sensory Perception Quotient (SPQ). Higher levels of food avoidant behaviours, in terms of food fussiness, food neophobia and ARFID-associated behaviours, were identified in adults with TS compared to adults without TS. While heightened sensory sensitivity failed to predict food fussiness, greater sensitivity to taste was found to be predictive of food neophobia in TS. These are the first findings to suggest that food avoidant behaviours are more prevalent for adults with TS and signal a need to address health implications.

LRRTM4 Terminal Exon Duplicated in Family with Tourette Syndrome, Autism and ADHD

Tourette syndrome (TS) is a neurodevelopmental disorder characterised by motor and vocal tics and strong association with autistic deficits, obsessive–compulsive disorder (OCD) and attention-deficit/hyperactivity disorder (ADHD). The genetic overlap between TS and autism spectrum disorder (ASD) includes those genes that encode the neurexin trans-synaptic connexus (NTSC) inclusive of the presynaptic neurexins (NRXNs) and postsynaptic neuroligins (NLGNs), cerebellin precursors (CBLNs in complex with the glutamate ionotropic receptor deltas (GRIDs)) and the leucine-rich repeat transmembrane proteins (LRRTMs). In this study, we report the first evidence of a TS and ASD association with yet another NTSC gene family member, namely LRRTM4. Duplication of the terminal exon of LRRTM4 was found in two females with TS from the same family (mother and daughter) in association with autistic traits and ASD.

The female Tourette patient: Sex differences in Tourette Disorder

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

Ticked Off: Anger Outbursts and Aggressive Symptoms in Tourette Disorder

Tourette disorder is a complex neuropsychiatric syndrome of childhood onset characterized by multiple motor and phonic tics and is associated with high rates of psychiatric comorbidity. Symptoms of impulsive aggression (explosive outbursts or "rage") are commonly encountered in the clinical setting, cause significant morbidity, and pose diagnostic and treatment challenges. These symptoms may be multifactorial in etiology and result from a complex interplay of illness severity and psychosocial factors. Treatment strategies require careful differential diagnostic evaluation and include both behavioral and pharmacologic interventions.

Incidence of Autism Spectrum Disorder in Youths Affected by Gilles de la Tourette Syndrome Based on Data from a Large Single Italian Clinical Cohort

Gilles de la Tourette syndrome (GTS) and autism spectrum disorder (ASD) are etiologically related neurodevelopmental disorders with an onset age before 18 years and a reported comorbidity of 2.9–20%. The aim of the present study was to identify the incidence of ASD in a large clinical sample of individuals affected by GTS and to compare our results with previously reported incidences. We retrospectively analyzed clinical data (n = 1200) from January 2010 to March 2019 obtained from the outpatient Catania Tourette Clinic, part of the Child and Adolescent Neurology and Psychiatry of the Medical and Experimental Department of Catania University. We used internationally validated evaluation tools. The neuropsychological evaluation was carried out by an expert and a certificated team of child and adolescent neurologists, supervised by two expert child neurologists (R.R. and M.G.). We investigated 975 GTS-affected individuals of various socioeconomic levels aged 5–18 years, and 8.9% (n = 87) were affected by ASD. The incidence of GTS with ASD was significantly lower (p < 0.001) in children than in adolescents. No statistically significant differences were found in the sex distribution and age of onset of tics between individuals with GTS alone and those with GTS and ASD. The incidence of GTS and ASD comorbidity in this study was high, and this has several implications in terms of treatment and prognosis.

Neuroimaging the emotional modulation of urge inhibition in Tourette Syndrome

Tourette Syndrome (TS) is a neuropsychiatric condition characterized by tics that are typically preceded by uncomfortable urges that build until the tic is performed. Both tics and their associated urges are commonly exacerbated during states of heightened emotion. However, the neural substrates that are responsible for the development of urges have not been fully elucidated, particularly with regards to the influence of emotion. In this study, we investigate the brain areas associated with the development of urges and their modulation by emotion in patients with TS. Moreover, we explore the influence of obsessive-compulsive symptoms (OCS) which are commonly comorbid in TS. Forty patients with TS and 20 healthy controls completed an emotional blink suppression paradigm while undergoing functional magnetic resonance imaging. For the paradigm, participants completed alternating blocks of blink inhibition and free blinking while viewing pictures of angry and neutral facial expressions. Compared to controls, patients exhibited greater activity in the superior temporal gyrus and midcingulate during the inhibition of urges. Within the patient group, tic severity was associated with activity in the superior frontal gyrus during the angry inhibition contrast as compared to neutral; greater premonitory urge severity was associated with greater activity in the hippocampus, middle temporal gyrus and in the subcortex; blink inhibition ability was negatively associated with activity in the thalamus and insula. There were no significant associations with OCS severity for the emotion-related contrasts. The observed activated regions may represent a network that produces urges in patients, or alternatively, could represent compensatory cortical activity needed to keep urges and tics under control during emotional situations. Additionally, our findings suggest that OCS in the context of TS is similar to traditional obsessive-compulsive disorder and is neurobiologically dissociable from tics.

Indicators of Social Competence and Social Participation Among US Children With Tourette Syndrome

Children with Tourette syndrome often have behavioral and social difficulties, which may be associated with co-occurring mental, emotional, or behavioral disorders. This study investigated social competence, including behavioral problems and social skills, and social activities between children with and without Tourette syndrome using a nationally representative sample. In the 2007 National Survey of Children's Health, parents reported on health care provider diagnosis of Tourette syndrome, co-occurring mental, emotional, or behavioral disorders, and indicators of social competence. Children aged 6-17 years with and without Tourette syndrome were compared. Most (78.7%) children with Tourette syndrome had a co-occurring mental, emotional, or behavioral disorder. Children with Tourette syndrome had significantly lower social competence, exhibited by higher levels of behavior problems (mean score 11.6 for Tourette syndrome and 9.0 for no Tourette syndrome) and lower levels of social skills (mean 15.3) than children without a Tourette syndrome diagnosis (mean 17.1); however, these associations were no longer significant after controlling for co-occurring mental, emotional, or behavioral disorders. Moderate to severe Tourette syndrome was associated with the highest ratings of behavioral problems and the lowest ratings of social skills. Children with and without Tourette syndrome were equally likely to participate in social activities; the difference for children with moderate to severe Tourette syndrome being less likely to participate in activities compared to children with mild Tourette syndrome had a chi-square test P value of .05. In conclusion, Tourette syndrome was associated with lower social competence, particularly for children with moderate to severe Tourette syndrome. Monitoring social functioning and co-occurring conditions among children with Tourette syndrome, and referral for evidence-based interventions when needed, may benefit overall health and functioning.

Interventions for tic disorders: An updated overview of systematic reviews and meta analyses

To conduct an updated overview of systematic reviews (SRs) summarizing the efficacy and safety of various strategies used to treat tic disorders (TDs) in children. We searched the Cochrane Library, PubMed, EMBASE, and relevant reference lists for articles published between the search deadline from our last overview and April 2019 and included 16 SRs. The results presented that antipsychotics, a2-adrenergic receptor agonists, and HRT/CBIT still appeared to be the most robust evidence-based options for the treatment of TDs. Compared with our last overview, more robust evidence showed that aripiprazole and acupuncture was effective treatment in treating children TDs, and DBS for medication-refractory and severely affected patients. In addition, physical activity or exercise may be promising treatments, and the clonidine adhesive patch is an effective, safe, and convenient treatment option for TDs. Moreover, methylphenidate, guanfacine, and desipramine appeared to reduce ADHD symptoms in children with tics. However, no research studies have examined HRT/CBIT alone compared with HRT/CBIT in combination with medication. More high-quality clinical trials comparing different interventions for TDs including economic evaluations should be encouraged.

Tourette Syndrome Risk Genes Regulate Mitochondrial Dynamics, Structure, and Function

Gilles de la Tourette syndrome (GTS) is a neurodevelopmental disorder characterized by motor and vocal tics with an estimated prevalence of 1% in children and adolescents. GTS has high rates of inheritance with many rare mutations identified. Apart from the role of the neurexin trans-synaptic connexus (NTSC) little has been confirmed regarding the molecular basis of GTS. The NTSC pathway regulates neuronal circuitry development, synaptic connectivity and neurotransmission. In this study we integrate GTS mutations into mitochondrial pathways that also regulate neuronal circuitry development, synaptic connectivity and neurotransmission. Many deleterious mutations in GTS occur in genes with complementary and consecutive roles in mitochondrial dynamics, structure and function (MDSF) pathways. These genes include those involved in mitochondrial transport (NDE1, DISC1, OPA1), mitochondrial fusion (OPA1), fission (ADCY2, DGKB, AMPK/PKA, RCAN1, PKC), mitochondrial metabolic and bio-energetic optimization (IMMP2L, MPV17, MRPL3, MRPL44). This study is the first to develop and describe an integrated mitochondrial pathway in the pathogenesis of GTS. The evidence from this study and our earlier modeling of GTS molecular pathways provides compounding support for a GTS deficit in mitochondrial supply affecting neurotransmission.

Association of Tourette Syndrome and Chronic Tic Disorders With Objective Indicators of Educational Attainment: A Population-Based Sibling Comparison Study

Importance

The influence of Tourette syndrome and chronic tic disorders on academic performance has not been objectively quantified.

Objective

To investigate the association of Tourette syndrome and chronic tic disorders with objectively measured educational outcomes, adjusting for measured covariates and unmeasured factors shared between siblings and taking common psychiatric comorbidities into account.

Design, Setting, and Participants

A population-based birth cohort consisting of all individuals born in Sweden from 1976 to 1998 was followed up until December 2013. Individuals with organic brain disorders, mental retardation, and 2 foreign-born parents were excluded. We further identified families with at least 2 singleton full siblings and families with siblings discordant for Tourette syndrome or chronic tic disorders.

Exposures

Previously validated International Classification of Diseases diagnoses of Tourette syndrome or chronic tic disorders in the Swedish National Patient Register.

Main Outcomes and Measures

Eligibility to access upper secondary school after compulsory education, finishing upper secondary school, starting a university degree, and finishing a university degree.

Results

Of the 2 115 554 individuals in the cohort, 3590 had registered a diagnosis of Tourette syndrome or a chronic tic disorder in specialist care (of whom 2822 [78.6%] were male; median [interquartile] age at first diagnosis, 14.0 [11-18] years). Of 726 198 families with at least 2 singleton full siblings, 2697 included siblings discordant for these disorders. Compared with unexposed individuals, people with Tourette syndrome or chronic tic disorders were significantly less likely to pass all core and additional courses at the end of compulsory school (odds ratios ranging from 0.23 [95% CI, 0.20-0.26] for the handcraft textile/wood course to 0.36 [95% CI, 0.31-0.41] for the English language course) and to access a vocational program (adjusted OR [aOR], 0.31; 95% CI, 0.28-0.34) or academic program (aOR, 0.43; 95% CI, 0.39-0.47) in upper secondary education. Individuals with the disorders were also less likely to finish upper secondary education (aOR, 0.35; 95% CI, 0.32-0.37), start a university degree (aOR, 0.41; 95% CI, 0.37-0.46), and finish a university degree (aOR, 0.39; 95% CI, 0.32-0.48). The results were only marginally attenuated in the fully adjusted sibling comparison models. Exclusion of patients with neuropsychiatric comorbidities, particularly attention-deficit/hyperactivity disorder and pervasive developmental disorders, resulted in attenuated estimates, but patients with Tourette syndrome or chronic tic disorders were still significantly impaired across all outcomes.

Conclusions and Relevance

Help-seeking individuals with Tourette syndrome or chronic tic disorders seen in specialist settings experience substantial academic underachievement across all educational levels, spanning from compulsory school to university, even after accounting for multiple confounding factors and psychiatric comorbidities.

Social communication deficits and restricted repetitive behavior symptoms in Tourette syndrome

Background: Autism spectrum disorders (ASD) have been found to occur more frequently in individuals with Tourette syndrome (TS) than in the general population. Similarities exist between ASD and TS clinically, which suggests a potential relationship between the two conditions. Purpose: The purpose of this study was to explore the occurrence of autism-related features in ASD and TS, focusing on areas of overlap and difference. Patients and methods: This study examined the nature and extent of autistic traits as measured by the Social Communication Questionnaire (SCQ) in a sample with a diagnosis of TS, a sample diagnosed to have ASD, and a normative general population sample. Results: The TS sample had significantly higher mean SCQ scores than the general population, but generally lower scores than the ASD sample. The group differences in mean SCQ scores between the TS and ASD sample were significant except in the domain of restricted repetitive behaviours (RRB). Conclusion: This suggests that ASD traits occur commonly in the TS population, with a significant overlap in certain clinical features. This was especially the case for complex movements or repetitive behaviours, which may represent either: i) a shared phenotype which is subclinical, ii) a phenocopy where some clinical symptoms mimic each other, or iii) a co-morbidity. Awareness of this association can be useful in identifying these symptoms as part of the comprehensive assessment of TS and addressing these to improve the overall clinical outcomes in these patients.

Beliefs about Tic Disorders and Tourette's Syndrome in South Korea: An Online Panel Survey

Objectives

This study investigates lay beliefs about the etiology and treatments of tic disorder and Tourette's syndrome, as well as identifying sociodemographic and personality variables affecting these beliefs among South Koreans.

Methods

In total, 673 participants (mean age 41.77±12.03 years) completed an online survey regarding their beliefs about tic disorder and Tourette's syndrome. The factors related to their lay beliefs about the disorders were analyzed, and the correlates were investigated.

Results

Results indicated that lay people in South Korea held strong beliefs that the causes of tic disorder and Tourette's syndrome lie within the parenting/psychological and neurological/biological categories, compared to the dietary/environmental one. Among the sociodemographic variables, sex, age, and levels of subjective mental health knowledge were primarily associated with the aforementioned beliefs. Familiarity with tic disorder and Tourette's syndrome was also associated with these beliefs. Among the personality traits investigated, extraversion and conscientiousness had significant influences on the beliefs people had about tic disorder and Tourette's syndrome.

Conclusion

The results suggest that both policy makers and mental health service providers should adopt a strategic approach for developing and implementing health education interventions about tic disorder and Tourette's syndrome because individual sociodemographic variables, familiarity with the disorders, and personality traits are all associated with the beliefs about these disorders.

First behavioural assessment of a novel Immp2l knockdown mouse model with relevance for Gilles de la Tourette syndrome and Autism spectrum disorder

Gilles de la Tourette syndrome (GTS) is a neurodevelopmental disorder, which shares some clinical features with Autism spectrum disorder (ASD). The genetic factors relevant to the development of both disorders are yet to be fully understood, however, some genetic association studies have identified inner mitochondrial membrane peptidase subunit 2 (IMMP2L) as a potential risk gene for both GTS and ASD. The impact of Immp2l deficiency on behavioural domains is currently unknown. A new genetic mouse model for Immp2l was developed. Adult heterozygous (HET) and homozygous (HOMO) Immp2l knockdown (Immp2l KD) mice of both sexes were compared to wild type-like (WT) littermates in the open field (OF), social interaction, novel object recognition, marble burying, and prepulse inhibition (PPI). The effect of acute dexamphetamine (2 mg/kg) on OF behaviour was also determined. OF locomotion was significantly higher in HET compared to HOMO male littermates. Male and female HOMO mice were much more sensitive to the locomotor-stimulating effects of dexamphetamine (DEX), whereas only HOMO males exhibited significant increased DEX-induced OF exploration compared to control groups. HOMO females failed to habituate to an acoustic startle stimulus. Furthermore, compared to HOMO females, HET females showed reduced social interaction, and a similar trend was seen in HET males. The Immp2l KD mouse model possesses moderate face validity for preclinical research into GTS and ASD, in particular as dysfunctional dopaminergic neurotransmission appears to be one mechanism leading to disease presentation. The sex-dependent differences observed in most findings reinforce the strong influence of sex in the pathophysiology of GTS and ASD.

Neurodevelopmental disorders: prevalence and comorbidity in children referred to mental health services

BACKGROUND

Accurate prevalence rates of the neurodevelopmental disorders (ND) and comorbid conditions in child and adolescent mental health services (CAMHS) are essential for treatment planning and organization of health care. However, valid and reliable prevalence estimates from Nordic CAMHS populations are scarce, and the published findings vary.

AIMS

To report prevalence rates of ND (attention-deficit hyperactivity disorder: ADHD, tic disorder: TD or autism spectrum disorder: ASD) and comorbid disorders by a validated diagnostic instrument in children referred to CAMHS outpatient clinics.

METHODS

Parents of 407 consecutively referred children aged 7-13 years were interviewed with the semistructured interview schedule for affective disorders and schizophrenia, present and lifetime version (Kiddie-SADS-PL) at time of admittance.

RESULTS

One or more ND was diagnosed in 226 children (55.5%; 69.9% boys): ADHD (44.5%; 68.5% boys); TD (17.7%; 77.8% boys) and ASD (6.1%; 76% boys). Among children with ND 70 (31.0%) had only one ND with no comorbid disorder, 49 (21.7%) had more than one ND (homotypic comorbidity) and 131 (58%) had a non-ND psychiatric disorder (heterotypic comorbidity). Anxiety disorders were the most frequently occurring heterotypic comorbidity in all three ND. Comorbid depressive disorder was associated with older age, and comorbid anxiety disorder with female gender.

CONCLUSION

In children referred to CAMHS, ND constitute the most frequently occurring group of disorders, with high rates of both homotypic and heterotypic comorbidity. This needs to be taken into consideration in health service planning and treatment delivery.

Impact of Tourette Syndrome on School Measures in a Nationally Representative Sample

OBJECTIVE

Children with Tourette syndrome (TS) are at risk for a variety of co-occurring conditions and learning and school problems. The purpose of this study was to determine the impact of TS and co-occurring conditions on school measures.

METHODS

Parent-reported data from the 2007-2008 and 2011-2012 National Survey of Children's Health were combined (n = 129,353 children aged 6-17 yrs). Parent report of health care provider diagnosis of TS; co-occurring mental, emotional, and behavioral conditions; learning and language conditions; and school measures were assessed. School measures included type of school, individual education plan (IEP), number of school days missed, school problems, doing well in school, doing homework, and repeating a grade. Children with TS were compared with those who never had TS on school measures accounting for co-occurring conditions.

RESULTS

After adjusting for demographics, compared with children without TS, children currently with TS were more likely to have an IEP, have a parent contacted about school problems, and not complete homework. After further adjusting for co-occurring conditions, only IEP status remained statistically significant. Compared with children with mild TS, children with moderate or severe TS were more likely to have an IEP, repeat a grade, encounter school problems, and not care about doing well in school.

CONCLUSION

Tourette syndrome severity and co-occurring conditions are associated with school challenges and educational service needs. Awareness among health care providers, teachers and parents of the potential challenges related to both TS and co-occurring conditions would help to best support the child's education.

Tourette syndrome and other neurodevelopmental disorders: a comprehensive review

Gilles de la Tourette syndrome (TS) is a complex developmental neuropsychiatric condition in which motor manifestations are often accompanied by comorbid conditions that impact the patient's quality of life. In the DSM-5, TS belongs to the "neurodevelopmental disorders" group, together with other neurodevelopmental conditions, frequently co-occurring. In this study, we searched the PubMed database using a combination of keywords associating TS and all neurodevelopmental diagnoses. From 1009 original reports, we identified 36 studies addressing TS and neurodevelopmental comorbidities. The available evidence suggests the following: (1) neurodevelopmental comorbidities in TS are the rule, rather than the exception; (2) attention deficit/hyperactivity disorder (ADHD) is the most frequent; (3) there is a continuum from a simple (TS + ADHD or/and learning disorder) to a more complex phenotype (TS + autism spectrum disorder). We conclude that a prompt diagnosis and a detailed description of TS comorbidities are necessary not only to understand the aetiological basis of neurodevelopmental disorders but also to address specific rehabilitative and therapeutic approaches.

Autism Spectrum Symptoms in a Tourette's Disorder Sample

OBJECTIVE

Tourette's disorder (TD) and autism spectrum disorder (ASD) share clinical features and possibly an overlapping etiology. The aims of this study were to examine ASD symptom rates in participants with TD, and to characterize the relationships between ASD symptom patterns and TD, obsessive-compulsive disorder (OCD), and attention-deficit/hyperactivity disorder (ADHD).

METHOD

Participants with TD (n = 535) and their family members (n =234) recruited for genetic studies reported TD, OCD, and ADHD symptoms and completed the Social Responsiveness Scale Second Edition (SRS), which was used to characterize ASD symptoms.

RESULTS

SRS scores in participants with TD were similar to those observed in other clinical samples but lower than in ASD samples (mean SRS total raw score = 51; SD = 32.4). More children with TD met cut-off criteria for ASD (22.8%) than adults with TD (8.7%). The elevated rate in children was primarily due to high scores on the SRS Repetitive and Restricted Behaviors (RRB) subscale. Total SRS scores were correlated with TD (r = 0.27), OCD (r = 0.37), and ADHD (r = 0.44) and were higher among individuals with OCD symptom-based phenotypes than for those with tics alone.

CONCLUSION

Higher observed rates of ASD among children affected by TD may in part be due to difficulty in discriminating complex tics and OCD symptoms from ASD symptoms. Careful examination of ASD-specific symptom patterns (social communication vs. repetitive behaviors) is essential. Independent of ASD, the SRS may be a useful tool for identifying patients with TD with impairments in social communication that potentially place them at risk for bullying and other negative sequelae.

Clonidine adhesive patch for the treatment of tic disorders: A systematic review and meta-analysis

OBJECTIVE

The aim of this study was to evaluate the efficacy and safety of clonidine adhesive patch for tic disorders (TDs).

METHODS

Medline, Embase, Cochrane central register of controlled trials and Chinese databases of CBM, CNKI were searched from inception to 08.2016 for randomized controlled studies (RCTs), open-label control studies of clonidine adhesive patch versus other medications or/and placebo for TDs. The cochrane Handbook for Systematic Reviews of Interventions was used to guide our study.

RESULTS

Six studies involving 1145 participants were included in this study. Among these studies, two study (N = 513 patients) used placebo as a control and four studies (N = 632 patients) used positive drug controls. The results of meta-analysis suggested that clonidine adhesive patch may be as effective as haloperidol or tiapride for TDs. Adverse events (AEs) were reported in all studies, and the most common AEs of clonidine adhesive patch were rash (8.9%), lightheadedness (8.0%), dry mouth (4.0%). The AEs of clonidine adhesive patch were slight.

CONCLUSION

These data provide moderate quality evidence that clonidine adhesive patch might be an effective and safe treatment option for TDs, and results from further trials are urgently needed to extend the evidence base.

Abating Mercury Exposure in Young Children Should Include Thimerosal-Free Vaccines

Pediatric immunization is essential to prevent, control and eradicate children`s infectious diseases. Newborns and infants in less developed countries have a concentrated schedule of Thimerosal-containing vaccines (TCVs); pregnant mothers are also immunized with TCVs. Metabolic changes during early development are demonstrably an important risk factor for ethylmercury (EtHg) effects on neurodevelopment, while exposure to Thimerosal sensitizes susceptible individuals to life-long contact dermatitis. Concerns regarding toxicity of Hg have moved rich nations to withdraw it from medicines and, in particular, Thimerosal from pediatric vaccines; it has been more than 20 years since rich countries started using Thimerosal-free vaccines. TCVs and Thimerosal-free vaccines show dissimilar profiles of adverse effects. Thimerosal-free vaccines have shown a decrease in contact dermatitis, while TCVs showed a significant association with increased risk of tic disorders; in some circumstances, EtHg in combination with other neurotoxic substances negatively impacted neurobehavioral tests. In studies that explored vaccines and risk of tics, Thimerosal was a necessary factor. However, when the binary exposure to organic Hg forms (TCV-EtHg and fish-MeHg) was considered, effects on neurobehavioral tests were inconsistent.

CONCLUSIONS

(a) The indiscriminate use of pediatric-TCVs in less developed countries carries an unjustifiable and excessive EtHg exposure with an unnecessary risk of neurotoxicity to the developing brain; (b) measurable benefits (of Thimerosal-free) and measurable risks of tic disorders have been associated with the (Thimerosal-containing) type of vaccine;

Putting the Pieces Together in Gilles de la Tourette Syndrome: Exploring the Link Between Clinical Observations and the Biological Basis of Dysfunction

Gilles de la Tourette syndrome is a complex, idiopathic neuropsychiatric disorder whose pathophysiological mechanisms have yet to be elucidated. It is phenotypically heterogeneous and manifests more often than not with both motor and behavioral impairment, although tics are its clinical hallmark. Tics themselves present with a complex profile as they characteristically wax and wane and are often preceded by premonitory somatosensory sensations to which it is said a tic is the response. Highly comorbid with obsessive-compulsive disorder and attention deficit-hyperactivity disorder, it is purported to be an epigenetic, neurodevelopmental spectrum disorder with a complex genetic profile. It has a childhood onset, occurs disproportionately in males, and shows spontaneous symptomatic attenuation by adulthood in the majority of those afflicted. Although not fully understood, its neurobiological basis is linked to dysfunction in the cortico-basal ganglia-thalamo-cortical network. Treatment modalities for Tourette syndrome include behavioral, pharmacological and surgical interventions, but there is presently no cure for the disorder. For those severely affected, deep brain stimulation (DBS) has recently become a viable therapeutic option. A key factor to attaining optimal results from this surgery is target selection, a topic still under debate due to the complex clinical profile presented by GTS patients. Depending on its phenotypic expression and the most problematic aspect of the disorder for the individual, one of three brain regions is most commonly chosen for stimulation: the thalamus, globus pallidus, or nucleus accumbens. Neurophysiological analyses of intra- and post-operative human electrophysiological recordings from clinical DBS studies suggest a link between tic behavior and activity in both the thalamus and globus pallidus. In particular, chronic recordings from the thalamus have shown a correlation between symptomatology and (1) spectral activity in gamma band power and (2) theta/gamma cross frequency coherence. These results suggest gamma oscillations and theta/gamma cross correlation dynamics may serve as biomarkers for dysfunction. While acute and chronic recordings from human subjects undergoing DBS have provided better insight into tic genesis and the neuropathophysiological mechanisms underlying Tourette syndrome, these studies are still sparse and the field would greatly benefit from further investigations. This review reports data and discoveries of scientific and clinical relevance from a wide variety of methods and provides up-to-date information about our current understanding of the pathomechanisms underlying Tourette syndrome. It gives a comprehensive overview of the current state of knowledge and addresses open questions in the field.

Guanfacine Extended Release: A New Pharmacological Treatment Option in Europe

Children/adolescents with attention-deficit/hyperactivity disorder (ADHD) may have a poor or inadequate response to psychostimulants or be unable to tolerate their side-effects; furthermore, stimulants may be inappropriate because of co-existing conditions. Only one non-stimulant ADHD pharmacotherapy, the noradrenaline transporter inhibitor atomoxetine, is currently approved for use in Europe. We review recent advances in understanding of the pathophysiology of ADHD with a focus on the roles of catecholamine receptors in context of the α2A-adrenergic receptor agonist guanfacine extended release (GXR), a new non-stimulant treatment option in Europe. Neuroimaging studies of children/adolescents with ADHD show impaired brain maturation, and structural and functional anomalies in brain regions and networks. Neurobiological studies in ADHD and medication response patterns support involvement of monoaminergic neurotransmitters (primarily dopamine and noradrenaline). Guanfacine is a selective α2A-adrenergic receptor agonist that has been shown to improve prefrontal cortical cognitive function, including working memory. The hypothesized mode of action of guanfacine centres on direct stimulation of post-synaptic α2A-adrenergic receptors to enhance noradrenaline neurotransmission. Preclinical data suggest that guanfacine also influences dendritic spine growth and maturation. Clinical trials have demonstrated the efficacy of GXR in ADHD, and it is approved as monotherapy or adjunctive therapy to stimulants in Canada and the USA (for children and adolescents). GXR was approved recently in Europe for the treatment of ADHD in children and adolescents for whom stimulants are not suitable, not tolerated or have been shown to be ineffective. GXR may provide particular benefit for children/adolescents who have specific co-morbidities such as chronic tic disorders or oppositional defiant disorder (or oppositional symptoms) that have failed to respond to first-line treatment options.

Hoarding in Children With ADHD

OBJECTIVE

Although evidence suggests that hoarding may be associated with symptoms of ADHD, no study has examined this relationship in children.

METHOD

Participants included 99 youth diagnosed with ADHD (and a parent) seen in a general outpatient psychiatry clinic. Children completed the Obsessive-Compulsive Inventory-Child Version, the Revised Child Anxiety and Depression Scale, and the Rosenberg Self-Esteem Scale. Parents completed the Children's Saving Inventory and Vanderbilt ADHD Diagnostic Rating Scale-Parent Version.

RESULTS

Inattentive and hyperactive/impulsive symptoms were the only indicator that differentiated those with and without clinically significant hoarding. Symptoms of ADHD, but not nonhoarding obsessive-compulsive symptoms, significantly predicted hoarding. Inattention and hyperactivity/impulsivity were uniquely associated with individual hoarding features. Hoarding symptoms mediated the relationship between ADHD and oppositionality.

CONCLUSION

These findings contribute to the growing literature about the association between hoarding and ADHD.

Tics and Tourette syndrome in autism spectrum disorders

Autism spectrum disorders (ASDs) are more frequently associated with tic disorders than expected by chance. Variable rates of comorbidity have been reported and common genetic and neurobiological factors are probably involved. The aim of this study was to determine the rate of tic disorders in a clinical sample ( n = 105) of children and adolescents with ASDs and to describe the clinical characteristics of a group with comorbid ASDs and tics ( n = 24). The overlap between tics and other repetitive movements and behaviors in ASDs was carefully assessed. Among individuals with ASDs, 22 percent presented tic disorders: 11 percent with Tourette disorder (TD), and 11 percent with chronic motor tics. All had various degrees of cognitive impairment. An association between the level of mental retardation and tic severity was found. It is concluded that the occurrence of tics in ASDs should not be overlooked and should be carefully evaluated.

VISIT-TS: A multimedia tool for population studies on tic disorders

Population-based assessment of Tourette syndrome (TS) and other tic disorders produces a paradox. On one hand, ideally diagnosis of tic disorders requires expert observation. In fact, diagnostic criteria for TS explicitly require expert assessment of tics for a definite diagnosis. On the other hand, large-scale population surveys with expert assessment of every subject are impracticable. True, several published studies have successfully used expert assessment to find tic prevalence in a representative population (e.g. all students in a school district). However, extending these studies to larger populations is daunting.

We created a multimedia tool to demonstrate tics to a lay audience, discuss their defining and common attributes, and address features that differentiate tics from other movements and vocalizations. A first version was modified to improve clarity and to include a more diverse group in terms of age and ethnicity. The result is a tool intended for epidemiological research. It may also provide additional benefits, such as more representative minority recruitment for other TS studies and increased community awareness of TS.

Long-term Follow-up of a Case of Gilles de la Tourette's syndrome

Gilles de la Tourette's syndrome is a combined vocal and multiple motor tic disorder. Here, we present a case of Tourette's syndrome who attended our psychiatric causality with severe depression and suicidal ideation. On reviewing follow-up records of 23 years, we come to know about the academic decline and nicotine dependence in the early childhood. He also developed co-morbid obsessive compulsive disorder (OCD) along with severe depression. He was agitated and self-injurious. We diagnosed him as Gilles de la Tourette's syndrome with co-morbid OCD, depression, nicotine dependence. The patient was treated with haloperidol, sertraline, and clonidine when he developed mixed switch that necessitated us to stop sertraline. Hence, he was treated with a mood stabilizer and he remitted. Here, we want to show how Tourette's syndrome can take a longer course with different co-morbidities in a single person's life. As per our knowledge, such presentation is relatively rare in Indian literature.

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.

Difficulties experienced by young people with Tourette syndrome in secondary school: a mixed methods description of self, parent and staff perspectives

BACKGROUND

Tourette syndrome (TS) is a neurodevelopmental disorder characterised by motor and vocal tics. These involuntary movements and vocalizations can have a negative impact in the school environment. The paper presents a mixed methods description of the difficulties experienced by UK students with TS in secondary school, drawing on multiple perspectives.

METHODS

Thirty-five young people with TS (11 to 18 years), their parents (n = 35) and key members of school staff (n = 54) took part in semi-structured interviews about TS-related difficulties in secondary school. Theme analysis was used to identify school difficulties reported by the young people, before moving on to analysis of the parents' and staff members' transcripts. The most frequently occurring themes from the young people's accounts were then quantified in order to examine the level of agreement between informants and the association with clinical symptom severity.

RESULTS

A range of TS-related difficulties with academic work, and social and emotional well-being in school were reported by young people, parents and staff. Three superordinate themes are described: 1) TS makes school work more difficult, 2) Negative response to TS from staff and fellow students and 3) TS makes it more difficult to manage emotions in school. The three difficulties most frequently reported by the young people were problems concentrating in class, unhelpful responses by school staff to tics and difficulties with other students such as name-calling and mimicking tics. Additional difficulties reported by more than a quarter of young people related to homework, examinations, writing, anxiety and managing anger in school. Having more severe motor tics was associated with reporting difficulties with homework and handwriting, whereas having more severe phonic tics was associated with reporting unhelpful responses from staff. Young people and parents agreed more strongly with each other than they did with staff regarding school difficulties faced by individuals, and staff generally reported fewer TS-related difficulties.

CONCLUSIONS

TS can present a barrier to learning in several ways and can also affect interactions with others and emotional experiences in secondary school. Implications for supporting secondary school-aged students with TS are considered.

Staphylococcus aureus Colonization Modulates Tic Expression and the Host Immune Response in a Girl with Tourette Syndrome

A 9-year-old girl with Tourette syndrome (TS) and increased antibody levels against Streptococcus pyogenes was monitored longitudinally for the presence of nasopharyngeal bacteria, specific antibody titers, and autoimmunity directed against brain antigens. Microbiological monitoring indicated that the child was an intermittent Staphylococcus aureus nasopharyngeal carrier. Clinical improvements in motor tic frequency and severity were observed during the S. aureus colonization phase and were temporally correlated with the downregulation of anti-streptococcal and anti-D1/D2 dopamine receptor antibody production. After decolonization, clinical conditions reverted to the poor scores previously observed, suggesting a possible role of the immune response in bacterial clearance as a trigger of symptom recrudescence. These findings imply that a cause-effect relationship exists between S. aureus colonization and tic improvement, as well as between bacterial decolonization and tic exacerbation. Understanding the impact of S. aureus on the host adaptive immune response and the function of autoantibodies in the pathogenesis of TS may alter approaches for managing autoimmune neuropsychiatric and tic disorders.

[Chronic tics and Tourette syndrome in children and adolescents: diagnostic and treatment characteristics]

Chronic tics (CT) are observed in 3-4% population, Tourette syndrome (TS) in 0.1-3.0%. In most cases, tic disorders start at age 2-15 years, but frequently they are diagnosed late. Clinical presentations of tics and comorbid disorders are various and depend on child's age. Difficulties in treatment of CT are associated with their persistence and those for TS with the fluctuating course of tics and probable onset of the disease in the form of behavioral disorders. Treatment of CT and TS is individual. Methods of behavioral and psychotherapy are recommended for a certain period of time if tics do not hamper everyday life. Increase in tick frequency and severity indicate the necessity of using pharmacological treatment. The European recommendations on pharmacotherapy of tic disorders and the drugs available in Russia are considered. Results of the studies on the efficacy of antiepileptic drugs and tenoten children in CT and TS are presented.

Shared Brain Connectivity Issues, Symptoms, and Comorbidities in Autism Spectrum Disorder, Attention Deficit/Hyperactivity Disorder, and Tourette Syndrome

The prevalence of neurodevelopmental disorders, including autism spectrum disorder (ASD), attention deficit/hyperactivity disorder (ADHD), and Tourette syndrome (TS), has increased over the past two decades. Currently, about one in six children in the United States is diagnosed as having a neurodevelopmental disorder. Evidence suggests that ASD, ADHD, and TS have similar neuropathology, which includes long-range underconnectivity and short-range overconnectivity. They also share similar symptomatology with considerable overlap in their core and associated symptoms and a frequent overlap in their comorbid conditions. Consequently, it is apparent that ASD, ADHD, and TS diagnoses belong to a broader spectrum of neurodevelopmental illness. Biologically, long-range underconnectivity and short-range overconnectivity are plausibly related to neuronal insult (e.g., neurotoxicity, neuroinflammation, excitotoxicity, sustained microglial activation, proinflammatory cytokines, toxic exposure, and oxidative stress). Therefore, these disorders may a share a similar etiology. The main purpose of this review is to critically examine the evidence that ASD, ADHD, and TS belong to a broader spectrum of neurodevelopmental illness, an abnormal connectivity spectrum disorder, which results from neural long-range underconnectivity and short-range overconnectivity. The review also discusses the possible reasons for these neuropathological connectivity findings. In addition, this review examines the role and issue of axonal injury and regeneration in order to better understand the neuropathophysiological interplay between short- and long-range axons in connectivity issues.

A personal 35 year perspective on Gilles de la Tourette syndrome: prevalence, phenomenology, comorbidities, and coexistent psychopathologies

This Series is a personal narrative of my experience with patients with Gilles de la Tourette syndrome and covers its definition and history since the first description in 1825. Controversy entered the prevalence debate early. Although originally considered very rare, in the 1980s, Tourette's syndrome was reported to be common. However, Tourette's syndrome has been shown to occur at a prevalence of about 0·85% to 1%. Tourette's syndrome is more common in the male population, more prominent during childhood, and usually improves, but does not disappear with age. Tourette's syndrome is considered less common in people of sub-Saharan black African, African-American, and American Hispanic ethnic origin. The phenomenology is similar worldwide, indicating a biological basis. The hallmark characteristics are multiple motor and one or more vocal/phonic tics. Other associated features include premonitory urges, a waxing and waning course, and to a much lesser degree, coprolalia. Comorbid disorders are common and are suggested to include obsessive-compulsive disorder and behaviours, attention deficit hyperactivity disorder, and autistic spectrum disorder. Coexistent psychopathologies are suggested to include depression and conduct and personality disorders. Importantly, I argue that Tourette's syndrome is not a unitary condition. Finally, I offer suggestions for future research.

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

The aim of this study was to refine the population prevalence estimate of Tourette Syndrome (TS) in children and to investigate potential sources of heterogeneity in previously published studies. A systematic review was conducted and all qualifying published studies of TS prevalence were examined. Extracted data were subjected to a random-effects meta-analysis weighted by sample size; meta-regressions were performed to examine covariates that have previously been proposed as potential sources of heterogeneity. Twenty-six articles met study inclusion criteria. Studies derived from clinically referred cases had prevalence estimates that were significantly lower than those derived from population-based samples (P = 0.004). Among the 21 population-based prevalence studies, the pooled TS population prevalence estimate was 0.52% (95% confidence interval CI: 0.32-0.85). In univariable meta-regression analysis, study sample size (P = 0.002) and study date (P = 0.03) were significant predictors of TS prevalence. In the final multivariable model including sample size, study date, age, and diagnostic criteria, only sample size (P < 0.001) and diagnostic criteria (omnibus P = 0.003; Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision [DSM-IV-TR]: P = 0.005) were independently associated with variation in TS population prevalence across studies. This study refines the population prevalence estimate of TS in children to be 0.3% to 0.9%. Study sample size, which is likely a proxy for case assessment method, and the use of DSM-IV-TR diagnostic criteria are the major sources of heterogeneity across studies. The true TS population prevalence rate is likely at the higher end of these estimates, given the methodological limitations of most studies. Further studies in large, well-characterized samples will be helpful to determine the burden of disease in the general population.

The prevalence of tic disorders in children and adolescents in Brazil

Tourette syndrome (TS) and tic disorders represent events of familiar magnitude characterized by involuntary movements and/or vocalization. To determine the prevalence of TS/tic disorders we studied a sample of 762 subjects (388 M, 374 F), between 1992 and 1997, age 6 to 43 years old, taken out of a population of 10,155 subjects (4,918 M, 5,237 F; age: 3-56 years old). A structured 4-item questionnaire, direct interview (multistaged), >1 yr follow-up, were used. 9,565 subjects (4,614 M, 4,951 F) sent back the questionnaires, 3,354 of these (1,671 M, 1,683 F) with positive answers to tics. 42 subjects (31 M, 11 F, age: 7-21 years old, mean: 11 years old) met the DSM-III-R criteria. The total minimal prevalence of TS is 0.43%, with a 3:1 ratio male/female. The minimal prevalence of chronic tic disorder is 2.27%. The total minimal prevalence for tic disorders at all is 2.91%. No special education students participation.

The Prevalence of Tic Disorders and Clinical Characteristics in Children

BACKGROUND

Prevalence is a simple statement about the frequency of a disease in the population. For many medical conditions, including Tourette syndrome, there are true cases that have not been previously diagnosed due to problems of access to appropriate clinical services. Therefore, to obtain a trustworthy estimate of prevalence, it is necessary to go beyond cases identified in clinical settings and evaluate community samples.

METHOD

We reviewed 11 community surveys in children with Tourette syndrome (TS) published since 2000. We also examined the frequency of co-occurring psychiatric conditions in community samples and large clinically-ascertained samples.

RESULTS

Transient tics are relatively common affecting as many as 20% of school-age children. The 11 studies reviewed here offer a wide range of estimates from 2.6 to 38 per 1000 children for TS. Six studies provide estimates in a narrower range from 4.3 to 7.6 per 1000, but the confidence interval around this narrower range remains wide. Six studies provided results on chronic tic disorders ranging from 3 to 50 per 1000 for Chronic Motor Tic Disorder and 2.5 to 9.4 per 1000 for Chronic Vocal Tic Disorder. Community samples and large clinically-ascertained samples consistently show high rates of ADHD, disruptive behavior and anxiety disorders in children with TS.

CONCLUSIONS

The wide range of prevalence estimates for TS and chronic tic disorders is likely due to differences in sample size and assessment methods. The best estimate of prevalence for TS in school-age children is likely to fall between 4 and 8 cases per 1000. Clinical assessment of children with chronic tic disorders warrants examination of other problems such as ADHD, disruptive behavior and anxiety.

A nationwide register study of the characteristics, incidence and validity of diagnosed Tourette syndrome and other tic disorders

AIM

The aim of this study was to describe the characteristics and incidence rates of diagnosed tic disorders in the Finnish Hospital Discharge Register, including changing incidence rates between 1991 and 2010. We also aimed to validate the diagnoses of Tourette's syndrome recorded in the register.

METHODS

Children born between January 1, 1991 and December 31, 2010, who were diagnosed with tic disorders, were identified from the Finnish Hospital Discharge Register (n = 3003). We studied the validity of the Tourette's syndrome diagnoses by reviewing the medical charts of 88 children born since 1997 and carrying out telephone interviews with 55 of their guardians.

RESULTS

The incidence rates of all diagnosed tic disorders increased during the study period. A comorbid diagnosis of hyperkinetic disorder diagnosis was recorded in 28.2% of the children with Tourette's syndrome, and the validity of the register-based Tourette's syndrome diagnosis was approximately 95%.

CONCLUSION

This is the first nationwide study to demonstrate the increasing incidence of all register-based tic disorder diagnoses. The validity of the Tourette's syndrome diagnoses in the Finnish Hospital Discharge Register was good, and the data provided are suitable for use in further register-based studies of tic disorders.

A national profile of Tourette syndrome, 2011-2012

OBJECTIVE

To provide recent estimates of the prevalence of Tourette syndrome among a nationally representative sample of US children and to describe the association of Tourette syndrome with indicators of health and functioning.

METHODS

Data on 65,540 US children aged 6 to 17 years from the 2011-2012 National Survey of Children's Health were analyzed. Parents reported whether a health care provider had ever told them their child had Tourette syndrome or other neurobehavioral or chronic health conditions and whether their child had current Tourette syndrome.

RESULTS

Based on parents' report, 0.19% of US children had Tourette syndrome; the average age of diagnosis was 8.1 years. Children with Tourette syndrome, compared with those without, were more likely to have co-occurring neurobehavioral and other health conditions, meet criteria for designation as having a special health care need, receive mental health treatment, have unmet mental health care needs, and have parents with high parenting aggravation and parents who were contacted about school problems; they were less likely to receive effective care coordination or have a medical home. After controlling for co-occurring neurobehavioral conditions, the findings on parents being contacted about school problems and children having unmet mental health care needs were no longer significant.

CONCLUSIONS

Tourette syndrome is characterized by co-occurring neurobehavioral and other health conditions, and poorer health, education, and family relationships. The findings support previous recommendations to consider co-occurring conditions in the diagnosis and treatment of Tourette syndrome. Future research may explore whether having a medical home improves outcomes among children with Tourette syndrome.

Chromatin regulators, phenotypic robustness, and autism risk

Though extensively characterized clinically, the causes of autism spectrum disorder (ASD) remain a mystery. ASD is known to have a strong genetic basis, but it is genetically very heterogeneous. Recent studies have estimated that de novo disruptive mutations in hundreds of genes may contribute to ASD. However, it is unclear how it is possible for mutations in so many different genes to contribute to ASD. Recent findings suggest that many of the mutations disrupt genes involved in transcription regulation that are expressed prenatally in the developing brain. De novo disruptive mutations are also more frequent in girls with ASD, despite the fact that ASD is more prevalent in boys. In this paper, we hypothesize that loss of robustness may contribute to ASD. Loss of phenotypic robustness may be caused by mutations that disrupt capacitors that operate in the developing brain. This may lead to the release of cryptic genetic variation that contributes to ASD. Reduced robustness is consistent with the observed variability in expressivity and incomplete penetrance. It is also consistent with the hypothesis that the development of the female brain is more robust, and it may explain the higher rate and severity of disruptive de novo mutations in girls with ASD.