Provisional Tic Disorder is not so transient

Relationship Between Anxiety Symptoms and Age-Related Differences in Tic Severity

Purpose

Tic disorders are neurodevelopmental disorders characterized by movements or vocalizations, often accompanied by anxiety symptoms. However, the relationships between tic severity, age, and anxiety symptoms remain unclear. Here, we investigated the association between tic severity and age and examined how anxiety symptoms might influence this relationship.

Patients and Methods

Paediatric patients with tic disorders were recruited from the outpatient clinic of the in Department of Psychiatry at Beijing Children's Hospital, Capital Medical University. The final sample included 372 subjects (77 females, 295 males; mean age = 10.50 ± 2.70 years; age range: 6.33-15.92 years). Tic severity was assessed using the Yale Global Tic Severity Scale (YGTSS), while anxiety symptoms were measured using the Screen for Child Anxiety Related Emotional Disorders (SCARED).

Results

We found a significant positive correlation between both total and subscale anxiety scores and tic severity. Furthermore, anxiety symptoms, particularly separation anxiety, were found to be significantly correlated with age-related differences in tic severity. In the high anxiety group, tic severity increased significantly with age, mirroring the overall trend. Conversely, in the low anxiety group, tic severity remained relatively stable with age.

Conclusion

Our findings highlight the role of anxiety in the progression of tic disorders and emphasize the importance of addressing anxiety in the clinical management of children with tic disorders.

We've all been wrong about provisional tic disorder

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Developing a phenotype risk score for tic disorders in a large, clinical biobank

Tics are a common feature of early-onset neurodevelopmental disorders, characterized by involuntary and repetitive movements or sounds. Despite affecting up to 2% of children and having a genetic contribution, the underlying causes remain poorly understood. In this study, we leverage dense phenotype information to identify features (i.e., symptoms and comorbid diagnoses) of tic disorders within the context of a clinical biobank. Using de-identified electronic health records (EHRs), we identified individuals with tic disorder diagnosis codes. We performed a phenome-wide association study (PheWAS) to identify the EHR features enriched in tic cases versus controls (n = 1406 and 7030; respectively) and found highly comorbid neuropsychiatric phenotypes, including: obsessive-compulsive disorder, attention-deficit/hyperactivity disorder, autism spectrum disorder, and anxiety (p < 7.396 × 10-5). These features (among others) were then used to generate a phenotype risk score (PheRS) for tic disorder, which was applied across an independent set of 90,051 individuals. A gold standard set of tic disorder cases identified by an EHR algorithm and confirmed by clinician chart review was then used to validate the tic disorder PheRS; the tic disorder PheRS was significantly higher among clinician-validated tic cases versus non-cases (p = 4.787 × 10-151; β = 1.68; SE = 0.06). Our findings provide support for the use of large-scale medical databases to better understand phenotypically complex and underdiagnosed conditions, such as tic disorders.

Factors linked to prognosis in children with provisional tic disorder: a prospective cohort study

The purpose of the present study was to estimate the factors linked to the prognosis of children with provisional tic disorder (PTD). We conducted a prospective cohort study enrolled children with PTD who were subsequently followed-up at three-month intervals for 1 year post-enrolment. A total of 259 PTD patients were included in the final analysis. At the end of the follow-up period, 77 (30%) of the patients had achieved clinical remission. Result of the LASSO logistic regression analysis revealed that a disease duration >3 months (OR=4.20, 95% CI 1.20-14.73), moderate/severe tic severity (OR=5.57, 95% CI 2.26-13.76), and comorbid behavioral problems (OR=2.78, 95% CI 1.15-6.69) were significant factors linked to remission in the PTD patients. The path analysis model showed that comorbid behavioral problems and recurrence partially mediated the association between tic severity and remission, with a mediating effect of 37%. Conclusions: We have identified several significant factors linked to prognosis in children with PTD, including comorbid behavioral problems and recurrence, which were found to be important mediators. These findings provide new insights for the clinical management of patients with PTD.

Treating Tourette Together: An Agenda for Patient-Centered Research Focused on Comprehensive Behavioral Intervention for Tics

To establish a patient-centered agenda for research that will lead to effective, widespread availability, adoption, and utilization of evidence-based behavioral treatment of Tourette syndrome and other tic disorders (TDs), we planned and executed a multistage, collaborative "Treating Tourette Together" research planning project with researchers, clinicians, patients, families, and other interested parties. Priorities for future behavioral treatment research were solicited from these parties via anonymous community surveys, a 2-day research planning summit with 46 individuals representing key stakeholder groups, and community response to summit reports. Four high-priority research domains were identified: (a) expanding treatment access, (b) improving treatment outcomes, (c) optimizing treatment within a broader care model, and (d) evaluating outcomes beyond tic severity. Community-engaged participatory research models can efficiently delineate clear and actionable priorities for clinical research. This approach holds promise for improving the impact of clinical research in TDs and other neuropsychiatric disorders.

Letting Tourette's be: The importance of understanding lived experience in research and the clinic

The most common clinical research question regarding Tourette syndrome focuses on tic reduction, which follows from classical 'lack of inhibition' models. Rooted in views about brain deficits, this model suggests that with higher severity and frequency, tics are necessarily disruptive and should therefore be inhibited. However, emerging calls from people with lived experience of Tourette syndrome suggest that this is too narrow a definition. This narrative literature review analyses issues with brain deficit views and qualitative research on tic context and feelings of compulsion. The results suggest the need for a more positive and encompassing theoretical and ethical position on Tourette's. The article puts forward an enactive analytical approach of 'letting be', that is, approaching a phenomenon without forcing preconceived reference structures onto it. We suggest using the identity-first term 'Tourettic'. Prioritizing the perspective of the 'Tourettic patient', it urges attentiveness to the everyday issues diagnosed people encounter and how these are embedded in further life. This approach highlights the strong relationship between the Tourettic persons' felt impairment, their adoption of an outsider's perspective, and feeling under constant scrutiny. It suggests that this felt impairment of tics can be reduced by creating a physical and social environment in which the person is 'let be' but not 'let go of'. WHAT THIS PAPER ADDS: Its theoretical position allows a more holistic view of Tourette's, integrating tics with oft-overlooked complex compulsions. The 'letting be' position also allows us to view why the presentation of Tourette's is likely to vary with gender and age of onset. 'Letting be' is a promising approach to improve a clinical understanding of Tourettic well-being over and above tic severity and frequency. It integrates quantitative research on Tourette syndrome in the neurosciences with qualitative neurodiversity literature in the medical humanities. It integrates ethical frameworks as developed in enactive philosophy with the conceptualization and treatment of tics and compulsions.

An Update on the Diagnosis and Management of Tic Disorders

Tic disorders (TDs) are a group of common neuropsychiatric disorders of childhood and adolescence. TDs may impact the physical, emotional, and social well-being of the affected person. In this review, we present an update on the clinical manifestations, pathophysiology, diagnosis, and treatment of TDs. We searched the PubMed database for articles on tics and Tourette syndrome. More than 400 articles were reviewed, of which 141 are included in this review. TDs are more prevalent in children than in adults and in males than in females. It may result from a complex interaction between various genetic, environmental, and immunological factors. Dysregulation in the cortico-striato-pallido-thalamo-cortical network is the most plausible pathophysiology resulting in tics. TD is a clinical diagnosis based on clinical features and findings on neurological examination, especially the identification of tic phenomenology. In addition to tics, TD patients may have sensory features, including premonitory urge; enhanced and persistent sensitivity to non-noxious external or internal stimuli; and behavioral manifestations, including attention deficit hyperactivity disorders, obsessive-compulsive disorders, and autism spectrum disorders. Clinical findings of hyperkinetic movements that usually mimic tics have been compared and contrasted with those of TD. Patients with TD may not require specific treatment if tics are not distressing. Psychoeducation and supportive therapy can help reduce tics when combined with medication. Dispelling myths and promoting acceptance are important to improve patient outcomes. Using European, Canadian, and American guidelines, the treatment of TD, including behavioral therapy, medical therapy, and emerging/experimental therapy, has been discussed.

Diagnostic Hierarchy of Tic Disorders in Real-World Clinical Practice

Objectives

According to the 10th revision of the International Classification of Diseases, the main categories of tic disorders (F95.0, F95.1, and F95.2) follow a diagnostic hierarchy based on the duration and diversity of tic symptoms. The present study investigated the use of this diagnostic hierarchy in real-world clinical practice.

Methods

Based on the National Health Insurance Service-National Health Information Database, the diagnosis of transient tic disorder (F95.0) made after a diagnosis of chronic motor or vocal tic disorder (F95.1) or Tourette's syndrome (F95.2) and diagnosis of chronic motor or vocal tic disorder (F95.1) made after a diagnosis of Tourette's syndrome (F95.2) were referred to as type A errors. The diagnosis of transient tic disorder (F95.0) repeated after a period of >12 months was referred to as type B error. Demographic and clinical differences according to the diagnostic error types were analyzed using analysis of variance, Student's t-tests, and chi-squared tests.

Results

Most participants (96.5%) were without errors in the diagnosis of tic disorders. Higher proportions of males (p=0.005) and antipsychotic prescriptions (p<0.001) were observed in patients with type A or B diagnostic errors. A higher proportion of health insurance holders was observed among those with type A errors (p=0.027).

Conclusion

Errors were absent in majority of the tic diagnoses in real-world clinical practice in terms of the diagnostic hierarchy.

Patients' experience of accessing support for tics from primary care in the UK: an online mixed-methods survey

BACKGROUND

Tics are common in children and young people and may persist into adulthood. Tics can cause challenges with social, occupational, physical, and academic functioning. The current study explores the perceptions of adults with tics and parents/carers of young people with tics regarding their experience of accessing support from professionals in primary care in the UK.

METHODS

Two online cross-sectional surveys were completed by 33 adults with tics and 94 parents/carers of children with tics. Participants were recruited across three online tic support groups. Tic specialist psychologists, academic researchers, and people with lived experience of tics provided feedback on the surveys before they were made available online. Mixed-method analyses were conducted on the surveys. Qualitative data from the free-text responses were analysed using thematic analysis and triangulated with quantitative findings where appropriate.

RESULTS

While some participants felt supported by general practitioners (GPs), many felt dismissed. The impact of tics was not always explored, nor information on tics provided, during the consultation. Although 78.7% of participants were referred to secondary care for their tics, some struggled to get the referral. Within secondary care, most adult respondents were assessed by neurologists whilst young people were typically assessed by paediatricians or psychiatrists. Most of these secondary care clinicians did not specialise in tic disorders, with only 27.9% of participants being assessed by tic specialists. Mode waitlist time was 3-6 months for young people and longer for adult respondents. Some participants were referred to multiple secondary care services, spanning neurology, paediatrics, and psychiatry, with each stating that they do not provide support for tics. 21% of participants mentioned being discharged from secondary care with no ongoing support. Almost one-third of respondents accessed support within private healthcare.

CONCLUSIONS

Generally, more negative than positive experiences were reported. Possible contributing factors included a lack of clear tic referral pathways, long waitlists, a lack of information about tics provided in primary care appointments and a lack of support offered following diagnosis by secondary care services, together with poor access to tic specialist clinicians. This study highlights areas where improvements to UK services for tics can be made.

Behavioral Interventions for Children and Adults with Tic Disorder

Over the past decade, behavioral interventions have become increasingly recognized and recommended as effective first-line therapies for treating individuals with tic disorders. In this article, we describe a basic theoretical and conceptual framework through which the reader can understand the application of these interventions for treating tics. The three primary behavioral interventions for tics with the strongest empirical support (habit reversal, Comprehensive Behavioral Intervention for Tics, and exposure and response prevention) are described. Research on the efficacy and effectiveness of these treatments is summarized along with a discussion of the research evaluating the delivery of these treatments in different formats and modalities. The article closes with a review of the possible mechanisms of change underlying behavioral interventions for tics and areas for future research.

Functional tic-like presentations differ strikingly from Provisional Tic Disorder

Background: Recent years have seen a dramatic increase in new "tic" cases in teens and young adults. These individuals often present with fulminant onset of symptoms not commonly seen in Tourette syndrome (TS) and are often diagnosed with Functional Neurological Symptom Disorder (FND-tic). However, some authors have questioned whether this illness truly differs from typical Provisional Tic Disorder (PTD) and TS. Previous studies have compared FND-tic, usually a few months after symptom onset, to patients with TS, usually years after symptom onset. We sought to test whether the presenting symptoms of FND-tic differ substantially from those in patients at a similar duration of symptoms who are later diagnosed with TS. Methods: This comparative study examines clinical features summarized from published reports of FND-tic with novel data from a longitudinal study of PTD. This study came from a referral center for TS and tic disorders and included 89 children with tics whose first tic occurred a median of 3.6 months earlier, nearly all of whom were diagnosed with a chronic tic disorder at follow-up. Specifically, we examine clinical features identified in a recent literature review as supporting a diagnosis of FND-tic, including symptom characteristics, course, severity and comorbidity. Results: Several clinical features dramatically distinguish the patients diagnosed with FND-tic from those diagnosed with typical PTD. For example, coprophenomena are reported at or shortly after symptom onset in over half of FND-tic patients, whereas even several months after onset, coprophenomena had occurred in only 1 of 89 children with PTD. Six clinical features each have a positive predictive value over 90% for FND-tic diagnosis if prior probability is 50%. Conclusions: These new data provide strong evidence supporting the diagnostic validity of FND-tic as distinct from TS.

A meta-analysis of genetic effects associated with neurodevelopmental disorders and co-occurring conditions

A systematic understanding of the aetiology of neurodevelopmental disorders (NDDs) and their co-occurrence with other conditions during childhood and adolescence remains incomplete. In the current meta-analysis, we synthesized the literature on (1) the contribution of genetic and environmental factors to NDDs, (2) the genetic and environmental overlap between different NDDs, and (3) the co-occurrence between NDDs and disruptive, impulse control and conduct disorders (DICCs). Searches were conducted across three platforms: Web of Science, Ovid Medline and Ovid Embase. Studies were included only if 75% or more of the sample consisted of children and/or adolescents and the studies had measured the aetiology of NDDs and DICCs using single-generation family designs or genomic methods. Studies that had selected participants on the basis of unrelated diagnoses or injuries were excluded. We performed multilevel, random-effects meta-analyses on 296 independent studies, including over four million (partly overlapping) individuals. We further explored developmental trajectories and the moderating roles of gender, measurement, geography and ancestry. We found all NDDs to be substantially heritable (family-based heritability, 0.66 (s.e. = 0.03); SNP heritability, 0.19 (s.e. = 0.03)). Meta-analytic genetic correlations between NDDs were moderate (grand family-based genetic correlation, 0.36 (s.e. = 0.12); grand SNP-based genetic correlation, 0.39 (s.e. = 0.19)) but differed substantially between pairs of disorders. The genetic overlap between NDDs and DICCs was strong (grand family-based genetic correlation, 0.62 (s.e. = 0.20)). While our work provides evidence to inform and potentially guide clinical and educational diagnostic procedures and practice, it also highlights the imbalance in the research effort that has characterized developmental genetics research.

Developing a Phenotype Risk Score for Tic Disorders in a Large, Clinical Biobank

Importance

Tics are a common feature of early-onset neurodevelopmental disorders, characterized by involuntary and repetitive movements or sounds. Despite affecting up to 2% of young children and having a genetic contribution, the underlying causes remain poorly understood, likely due to the complex phenotypic and genetic heterogeneity among affected individuals.

Objective

In this study, we leverage dense phenotype information from electronic health records to identify the disease features associated with tic disorders within the context of a clinical biobank. These disease features are then used to generate a phenotype risk score for tic disorder.

Design

Using de-identified electronic health records from a tertiary care center, we extracted individuals with tic disorder diagnosis codes. We performed a phenome-wide association study to identify the features enriched in tic cases versus controls (N=1,406 and 7,030; respectively). These disease features were then used to generate a phenotype risk score for tic disorder, which was applied across an independent set of 90,051 individuals. A previously curated set of tic disorder cases from an electronic health record algorithm followed by clinician chart review was used to validate the tic disorder phenotype risk score.

Main Outcomes and Measures

Phenotypic patterns associated with a tic disorder diagnosis in the electronic health record.

Results

Our tic disorder phenome-wide association study revealed 69 significantly associated phenotypes, predominantly neuropsychiatric conditions, including obsessive compulsive disorder, attention-deficit hyperactivity disorder, autism, and anxiety. The phenotype risk score constructed from these 69 phenotypes in an independent population was significantly higher among clinician-validated tic cases versus non-cases.

Conclusions and Relevance

Our findings provide support for the use of large-scale medical databases to better understand phenotypically complex diseases, such as tic disorders. The tic disorder phenotype risk score provides a quantitative measure of disease risk that can be leveraged for the assignment of individuals in case-control studies or for additional downstream analyses.

Mechanism of Qihuang needle therapy in the management of tic disorders: a clinical trial protocol

Background

Qihuang needle therapy is a newly developed acupuncture therapy to treat tic disorders in clinical practice. However, the mechanism to reduce tic severity remains unknown. Changes in intestinal flora and circulation metabolites are perhaps the potential pathogenesis of tic disorders. As a result, we present a protocol for a controlled clinical trial using multi-omics analysis to probe the mechanism of the Qihuang needle in managing tic disorders.

Methods

This is a matched-pairs design, controlled, clinical trial for patients with tic disorders. Participants will be allocated to either an experimental group or a healthy control group. The main acupoints are Baihui (GV20), Yintang (EX-HN3), and Jueyinshu (BL14). The experimental group will receive Qihuang needle therapy for a month, while the control group will receive no interventions.

Expected outcomes

The change in the severity of the tic disorder is set as the main outcome. Secondary outcomes include gastrointestinal severity index and recurrence rate, which will be calculated after a 12-week follow-up. Gut microbiota, measured by 16S rRNA gene sequencing; serum metabolomics, assessed via LC/MS; and serum zonulin, assessed by enzyme-linked immunosorbent assay (ELISA), will be used as biological specimen analysis outcomes. The present study will investigate the possible interactions between intestinal flora and serum metabolites and the improvement of clinical profiles, which may elucidate the mechanism of Qihuang needle therapy for tic disorders.

Trial registration

This trial is registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn/). Registration number: ChiCTR2200057723, Date: 2022-04-14.

Tourette syndrome research highlights from 2021

We summarize selected research reports from 2021 relevant to Tourette syndrome that the authors consider most important or interesting. The authors welcome article suggestions and thoughtful feedback from readers.

Myoclonus and other jerky movement disorders

Myoclonus and other jerky movements form a large heterogeneous group of disorders. Clinical neurophysiology studies can have an important contribution to support diagnosis but also to gain insight in the pathophysiology of different kind of jerks. This review focuses on myoclonus, tics, startle disorders, restless legs syndrome, and periodic leg movements during sleep. Myoclonus is defined as brief, shock-like movements, and subtypes can be classified based the anatomical origin. Both the clinical phenotype and the neurophysiological tests support this classification: cortical, cortical-subcortical, subcortical/non-segmental, segmental, peripheral, and functional jerks. The most important techniques used are polymyography and the combination of electromyography-electroencephalography focused on jerk-locked back-averaging, cortico-muscular coherence, and the Bereitschaftspotential. Clinically, the differential diagnosis of myoclonus includes tics, and this diagnosis is mainly based on the history with premonitory urges and the ability to suppress the tic. Electrophysiological tests are mainly applied in a research setting and include the Bereitschaftspotential, local field potentials, transcranial magnetic stimulation, and pre-pulse inhibition. Jerks due to a startling stimulus form the group of startle syndromes. This group includes disorders with an exaggerated startle reflex, such as hyperekplexia and stiff person syndrome, but also neuropsychiatric and stimulus-induced disorders. For these disorders polymyography combined with a startling stimulus can be useful to determine the pattern of muscle activation and thus the diagnosis. Assessment of symptoms in restless legs syndrome and periodic leg movements during sleep can be performed with different validated scoring criteria with the help of electromyography.

Prevalence of nail biting and its chronological relationship with tics in child and adolescent outpatients with Tourette syndrome: a single-centre, retrospective observational study

OBJECTIVE

To evaluate the prevalence of nail biting in child and adolescent outpatients at a single institution and the chronological relationship between nail biting and tics in patients with Tourette syndrome (TS) with or without attention-deficit hyperactivity disorder (ADHD).

DESIGN

Retrospective observational study.

SETTING

Teaching hospital in Taiwan.

PARTICIPANTS

All participants were aged 4-18 years, including 535 patients with TS, 230 patients with provisional tic disorder and 1460 patients without neurological or psychiatric disorders (controls).

OUTCOME MEASURES

Presence of nail biting, starting age for nail biting and starting age for motor and/or vocal tics.

RESULTS

Nail biting was more commonly observed in patients with TS (56.6%) than in patients with provisional tic disorder (27.4%) or controls (15.0%), regardless of sex (all p<0.020). Nail biting was also more common in patients with TS with ADHD than in those without (75.0% vs 47.6%; p<0.001), but the starting age was significantly later in those with concomitant ADHD than without (5.3 vs 3.8 years; p<0.001). In patients with TS, the onset of nail biting occurred earlier than that of tics, regardless of ADHD status.

CONCLUSION

Nail biting was more prevalent and occurred earlier than tics in patients with TS, regardless of ADHD status, in the study population.

Classification of tic disorders based on functional MRI by machine learning: a study protocol

INTRODUCTION

Tic disorder (TD) is a common neurodevelopmental disorder in children, and it can be categorised into three subtypes: provisional tic disorder (PTD), chronic motor or vocal TD (CMT or CVT), and Tourette syndrome (TS). An early diagnostic classification among these subtypes is not possible based on a new-onset tic symptom. Machine learning tools have been widely used for early diagnostic classification based on functional MRI (fMRI). However, few machine learning models have been built for the diagnostic classification of patients with TD. Therefore, in the present study, we will provide a study protocol that uses the machine learning model to make early classifications of the three different types of TD.

METHODS AND ANALYSIS

We planned to recruit 200 children aged 6-9 years with new-onset tic symptoms and 100 age-matched and sex-matched healthy controls under resting-state MRI scanning. Based on the neuroimaging data of resting-state fMRI, the support vector machine (SVM) model will be built. We planned to construct an SVM model based on functional connectivity for the early diagnosis classification of TD subtypes (including PTD, CMT/CVT, TS).

ETHICS AND DISSEMINATION

This study was approved by the ethics committee of Beijing Children's Hospital. The trial results will be submitted to peer-reviewed journals for publication.

TRIAL REGISTRATION NUMBER

ChiCTR2000033257.

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.

Fractality of tics as a quantitative assessment tool for Tourette syndrome

Tics manifest as brief, purposeless and unintentional movements or noises that, for many individuals, can be suppressed temporarily with effort. Previous work has hypothesized that the chaotic temporal nature of tics could possess an inherent fractality, that is, have neighbour-to-neighbour correlation at all levels of timescale. However, demonstrating this phenomenon has eluded researchers for more than two decades, primarily because of the challenges associated with estimating the scale-invariant, power law exponent—called the fractal dimension D_f—from fractional Brownian noise. Here, we confirm this hypothesis and establish the fractality of tics by examining two tic time series datasets collected 6–12 months apart in children with tics, using random walk models and directional statistics. We find that D_f is correlated with tic severity as measured by the YGTTS total tic score, and that D_f is a sensitive parameter in examining the effect of several tic suppression conditions on the tic time series. Our findings pave the way for using the fractal nature of tics as a robust quantitative tool for estimating tic severity and treatment effectiveness, as well as a possible marker for differentiating typical from functional tics.

Sex differences in patients with Tourette syndrome

BACKGROUND

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the presence of motor and phonic tics. It is at least three times more common in males compared with females; however, the clinical phenomenology between sexes has not been fully examined. We aimed to contrast the clinical features between males and females with TS and chronic tic disorder.

METHODS

We studied 201 consecutive patients fulfilling the diagnostic criteria for TS, persistent (or chronic) motor and vocal tic disorder and provisional tic disorder that were considered within the TS spectrum disorder. We performed blinded evaluations of video-recordings and retrospectively reviewed the clinical charts of all patients.

RESULTS

Age ranges between 4 and 65 years. Males represented 77.6% of patients in the cohort. Overall, no differences were observed in the frequency, distribution and complexity of tics between sexes, except for a higher frequency of attention-deficit/hyperactivity disorder (ADHD) (P = .003) among males. Patients younger than 18-years old, in addition to a higher frequency of ADHD (P = .026), males had a statistically higher frequency of complex motor tics (P = .049) and earlier age at onset (P = .072) than females in the multivariate regression analysis. However, these differences were lost in patients older than 18 years, due to increased complexity of tics in females with aging.

CONCLUSIONS

A sexual dimorphism was observed between patients with TS mainly before age of 18 years, suggesting an earlier onset of some types of tics and ADHD in males compared to females.

Exculpation and Stigma in Tourette Syndrome

Purpose

There is a widespread recognition that biomedical explanations offer benefits to those diagnosed with a mental disorder. Recent research points out that such explanations may nevertheless have stigmatizing effects. In this study, this ‘mixed blessing’  [2] account of biomedical explanations is investigated in a case of philosophical interest: Tourette Syndrome.

Method

We conducted a vignette survey with 221 participants in which we first assessed quantitative attributions of blame as well as the desire for social distance for behavior associated with Tourette Syndrome.

Results

In our study, it is confirmed that in the case of biomedical explanations, less blame is attributed than in the case of psychosocial explanations. When presented with a mixed (or an epigenetic) explanation stressing an entanglement of biological and psychosocial factors this did not increase blame attribution. The desire for social distance is unaffected by the type of explanation but the participants’ free text feedback indicates this might obfuscate an underlying dilemma between stigma and blame revealed in recent research.

Conclusion

There seems to be potential for blame reduction in explanations where biological and psychosocial factors are entangled. However, dynamic, ‘epigenetic’, explanations require further qualitative research to be performed as well as a philosophical framework to account for the ‘mixed blessings’ account.

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.

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.

Course of tic disorders over the lifespan

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

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.

Impairment of visually guided associative learning in children with Tourette syndrome

The major symptoms of Tourette syndrome are motor and vocal tics, but Tourette syndrome is occasionally associated with cognitive alterations as well. Although Tourette syndrome does not affect the majority of cognitive functions, some of them improve. There is scarce evidence on the impairment of learning functions in patients with Tourette syndrome. The core symptoms of Tourette syndrome are related to dysfunction of the basal ganglia and the frontostriatal loops. Acquired equivalence learning is a kind of associative learning that is related to the basal ganglia and the hippocampi. The modified Rutgers Acquired Equivalence Test was used in the present study to observe the associative learning function of patients with Tourette syndrome. The cognitive learning task can be divided into two main phases: the acquisition and test phases. The latter is further divided into two parts: retrieval and generalization. The acquisition phase of the associative learning test, which mainly depends on the function of the basal ganglia, was affected in the entire patient group, which included patients with Tourette syndrome with attention deficit hyperactivity disorder, obsessive compulsive disorder, autism spectrum disorder, or no comorbidities. Patients with Tourette syndrome performed worse in building associations. However, the retrieval and generalization parts of the test phase, which primarily depend on the function of the hippocampus, were not worsened by Tourette syndrome.

Hippocampal Volume in Provisional Tic Disorder Predicts Tic Severity at 12-Month Follow-up

Previous studies have investigated differences in the volumes of subcortical structures (e.g., caudate nucleus, putamen, thalamus, amygdala, and hippocampus) between individuals with and without Tourette syndrome (TS), as well as the relationships between these volumes and tic symptom severity. These volumes may also predict clinical outcome in Provisional Tic Disorder (PTD), but that hypothesis has never been tested. This study aimed to examine whether the volumes of subcortical structures measured shortly after tic onset can predict tic symptom severity at one-year post-tic onset, when TS can first be diagnosed. We obtained T1-weighted structural MRI scans from 41 children with PTD (25 with prospective motion correction (vNavs)) whose tics had begun less than 9 months (mean 4.04 months) prior to the first study visit (baseline). We re-examined them at the 12-month anniversary of their first tic (follow-up), assessing tic severity using the Yale Global Tic Severity Scale. We quantified the volumes of subcortical structures using volBrain software. Baseline hippocampal volume was correlated with tic severity at the 12-month follow-up, with a larger hippocampus at baseline predicting worse tic severity at follow-up. The volumes of other subcortical structures did not significantly predict tic severity at follow-up. Hippocampal volume may be an important marker in predicting prognosis in Provisional Tic Disorder.

The New Tics study: A Novel Approach to Pathophysiology and Cause of Tic Disorders

We report on the ongoing project "The New Tics Study: A Novel Approach to Pathophysiology and Cause of Tic Disorders," describing the work completed to date, ongoing studies and long-term goals. The overall goals of this research are to study the pathophysiology of Provisional Tic Disorder, and to study tic remission (or improvement) in a prospective fashion. Preliminary data collection for the project began almost 10 years ago. The current study is nearing completion of its third year, and has already reported several novel and important results. First, surprisingly, at least 90% of children who had experienced tics for only a mean of 3 months still had tics at the 12-month anniversary of their first tic, though in some cases tics were seen only with remote video observation of the child sitting alone. Thus almost all of them now had a DSM-5 diagnosis of Tourette's Disorder or Persistent (Chronic) Tic Disorder. Baseline clinical features that predicted 12-month outcome included tic severity, subsyndromal autism spectrum symptoms, an anxiety disorder, and a history of 3 or more phonic tics. Second, we found that poorer tic suppression ability when immediately rewarded for suppression predicted greater tic severity at follow-up. Third, striatal volumes did not predict outcome as hypothesized, but a larger hippocampus at baseline predicted worse severity at follow-up. Enrollment and data collection continue, including functional connectivity MRI (fcMRI) imaging, and additional analyses are planned once the full sample is enrolled.

Tic Suppression in Children With Recent-Onset Tics Predicts 1-Year Tic Outcome

Successful voluntary tic suppression is a key component of the behavioral interventions that are used to treat tic disorders. This study aimed to examine tic suppression in children with recent-onset tics and determine whether the capacity to suppress tics predicts future tic severity. We tested 45 children (30 male, mean age 7.74 years) with recent-onset tics (mean 3.47 months prior to the first study visit; baseline) and re-examined each child at the 12-month anniversary of the first recognized tic (follow-up). At the baseline visit, children performed a tic suppression task with several conditions: tic freely, inhibit tics given a verbal request, and inhibit tics in the presence of a reward. At the baseline visit, children with tics for only a few months could suppress their tics, and tic suppression was especially successful when they received an immediate and contingent reward. Additionally, the ability to suppress tics in the presence of a reward predicted tic severity at follow-up. These findings suggest that better inhibitory control of tics within months of tic onset may be an important predictor of future tic symptom outcome.

Tourette syndrome research highlights from 2018

This is the fifth yearly article in the Tourette Syndrome Research Highlights series, summarizing research from 2018 relevant to Tourette syndrome and other tic disorders. The authors briefly summarize reports they consider most important or interesting. The  highlights from 2019 article is being drafted on the Authorea online authoring platform, and readers are encouraged to add references or give feedback on our selections using the comments feature on that page. After the calendar year ends, the article is submitted as the annual update for the  Tics collection on F1000Research.