Influence of Gender on Tourette Syndrome Beyond Adolescence

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.

Human mutations in high-confidence Tourette disorder genes affect sensorimotor behavior, reward learning, and striatal dopamine in mice

Tourette disorder (TD) is poorly understood, despite affecting 1/160 children. A lack of animal models possessing construct, face, and predictive validity hinders progress in the field. We used CRISPR/Cas9 genome editing to generate mice with mutations orthologous to human de novo variants in two high-confidence Tourette genes, CELSR3 and WWC1. Mice with human mutations in Celsr3 and Wwc1 exhibit cognitive and/or sensorimotor behavioral phenotypes consistent with TD. Sensorimotor gating deficits, as measured by acoustic prepulse inhibition, occur in both male and female Celsr3 TD models. Wwc1 mice show reduced prepulse inhibition only in females. Repetitive motor behaviors, common to Celsr3 mice and more pronounced in females, include vertical rearing and grooming. Sensorimotor gating deficits and rearing are attenuated by aripiprazole, a partial agonist at dopamine type II receptors. Unsupervised machine learning reveals numerous changes to spontaneous motor behavior and less predictable patterns of movement. Continuous fixed-ratio reinforcement shows that Celsr3 TD mice have enhanced motor responding and reward learning. Electrically evoked striatal dopamine release, tested in one model, is greater. Brain development is otherwise grossly normal without signs of striatal interneuron loss. Altogether, mice expressing human mutations in high-confidence TD genes exhibit face and predictive validity. Reduced prepulse inhibition and repetitive motor behaviors are core behavioral phenotypes and are responsive to aripiprazole. Enhanced reward learning and motor responding occur alongside greater evoked dopamine release. Phenotypes can also vary by sex and show stronger affection in females, an unexpected finding considering males are more frequently affected in TD.

The role of neuroactive steroids in tic disorders

Tics are sudden, repetitive movements or vocalizations. Tic disorders, such as Tourette syndrome (TS), are contributed by the interplay of genetic risk factors and environmental variables, leading to abnormalities in the functioning of the cortico-striatal-thalamo-cortical (CSTC) circuitry. Various neurotransmitter systems, such as gamma-aminobutyric acid (GABA) and dopamine, are implicated in the pathophysiology of these disorders. Building on the evidence that tic disorders are predominant in males and exacerbated by stress, emerging research is focusing on the involvement of neuroactive steroids, including dehydroepiandrosterone sulfate (DHEAS) and allopregnanolone, in the ontogeny of tics and other phenotypes associated with TS. Emerging evidence indicates that DHEAS levels are significantly elevated in the plasma of TS-affected boys, and the clinical onset of this disorder coincides with the period of adrenarche, the developmental stage characterized by a surge in DHEAS synthesis. On the other hand, allopregnanolone has garnered particular attention for its potential to mediate the adverse effects of acute stress on the exacerbation of tic severity and frequency. Notably, both neurosteroids act as key modulators of GABA-A receptors, suggesting a pivotal role of these targets in the pathophysiology of various clinical manifestations of tic disorders. This review explores the potential mechanisms by which these and other neuroactive steroids may influence tic disorders and discusses the emerging therapeutic strategies that target neuroactive steroids for the management of tic disorders.

Sex Differences in People with Tourette Syndrome and Persistent Motor or Vocal Tic Disorder in the Tourette Association of America International Consortium for Genetics Database

Background and Objective

Tourette Syndrome (TS) and Persistent Motor or Vocal Tic Disorders (PMVT) are more prevalent in males (vs. females). Females with TS may have a delay in diagnosis, and more complex tic features (vs. males). With respect to comorbidities, obsessive-compulsive disorder (OCD) is more prevalent in females; attention-deficit hyperactivity disorder (ADHD) is more prevalent in males. Less is known about sex differences in PMVT. This study analyzes sex differences in outcomes among individuals with TS and PMVT in the Tourette Association of America International Consortium for Genetics dataset (TAAICG).

Design/Methods

Data from 2403 individuals (N=2109 TS; N=294 PMVT) from the TAAICG were analyzed to explore the relationship between sex and TS or PMVT outcomes: age at tic onset; age at diagnosis; time-to-diagnosis; tic severity; and comorbidity rates. Regression models were adjusted for age and family relationships to examine the impact of sex on outcomes.

Results

Females with TS (25.5% of the sample) had a later age of symptom onset (6.5±2.8 vs. 6.0±2.7; p=0.001), later age at diagnosis (13.3±11.2 vs. 10.7±8.1; p=0.0001), and a longer time-to-diagnosis [3 (1,7) vs. 2 (1,5), p=0.01] than males. The total Yale-Global Tic Severity Scale (YGTSS) was lower in females with TS (28.4±9.1 vs. 30.7±8.7); p<0.0001); OCD was slightly more prevalent in females (55% vs. 48.7%; p=0.01) although OCD severity did not differ by sex; ADHD was more prevalent in males (55.7% vs 38.9%; p<0.001). Females with TS had 0.46 lower odds of being diagnosed with TS (p<0.00001). Females with PMVT (42.9% of the sample) had an earlier age of symptom onset (7.9±3.3 vs. 8.9±3.7; p=0.05). Motor or vocal tic severity (YGTSS) was not significantly different. OCD, but not ADHD, was more prevalent in females (OCD: 41.9% vs. 22.2%; p<0.001: ADHD:16.5% vs 21.0%; p=0.4).

Conclusion

Females with TS are less likely to be formally diagnosed and have a later age of symptom onset, later age at diagnosis, longer time-to-diagnosis, higher prevalence of OCD, and lower prevalence of ADHD (vs. males). Females with PMVT have an earlier age of symptom onset, higher prevalence of OCD, but similar ADHD prevalence rates (vs. males). Females with TS and PMVT may be clinically different than males with TS. Future research is needed to understand differences longitudinally in TS and PMVT.

The Roles of Lifetime Enacted Stigma in Tic Symptoms among Young Adults with Tourette Syndrome

Background

Although rarely framed as enacted stigma, adults with Tourette syndrome (ATS) have long suffered from discrimination associated with their tic symptoms. Given the high stress levels of enacted stigma that ATS experience, it is expected that their tic symptoms are profoundly impacted. However, the evidence linking enacted stigma to ATS's tic symptoms remains limited.

Methods

This study used a secondary data-analysis approach to reanalyze the data from the follow-up phase of a multi-centered, randomized controlled trial in which a behavioral intervention was tested for its efficacy in managing tic symptoms. This study first conducted psychometric testing on a list of 16 enacted stigma events across five life stages and identified the underlying factor structure. The Yale Global Tic Severity Scale (YGTSS) was used to assess severity and impairment of current tic symptoms, whereas the Clinical Global Impression of Severity scale (CGI) was used to obtain the gestalt of clinical judgment on tic severity. A series of multivariate linear models were then fitted to test the relationships between different types of lifetime enacted stigma and current tic symptoms.

Results

The analytic sample included 73 young ATS (average age of 23.2 [standard deviation = 2.5] years). The factor analysis identified three types of enacted stigmas: "traumatic events," "confrontations," and "subtle mistreatments." In multivariate models, traumatic events significantly associated with YGTSS-severity, whereas subtle mistreatments provided additional explanations for CGI.

Conclusions

Enacted stigma may play important roles in shaping ATS's current tics symptom severity and, therefore, should be carefully considered in future intervention development.

Human mutations in high-confidence Tourette disorder genes affect sensorimotor behavior, reward learning, and striatal dopamine in mice

Tourette disorder (TD) is poorly understood, despite affecting 1/160 children. A lack of animal models possessing construct, face, and predictive validity hinders progress in the field. We used CRISPR/Cas9 genome editing to generate mice with mutations orthologous to human de novo variants in two high-confidence Tourette genes, CELSR3 and WWC1 . Mice with human mutations in Celsr3 and Wwc1 exhibit cognitive and/or sensorimotor behavioral phenotypes consistent with TD. Sensorimotor gating deficits, as measured by acoustic prepulse inhibition, occur in both male and female Celsr3 TD models. Wwc1 mice show reduced prepulse inhibition only in females. Repetitive motor behaviors, common to Celsr3 mice and more pronounced in females, include vertical rearing and grooming. Sensorimotor gating deficits and rearing are attenuated by aripiprazole, a partial agonist at dopamine type II receptors. Unsupervised machine learning reveals numerous changes to spontaneous motor behavior and less predictable patterns of movement. Continuous fixed-ratio reinforcement shows Celsr3 TD mice have enhanced motor responding and reward learning. Electrically evoked striatal dopamine release, tested in one model, is greater. Brain development is otherwise grossly normal without signs of striatal interneuron loss. Altogether, mice expressing human mutations in high-confidence TD genes exhibit face and predictive validity. Reduced prepulse inhibition and repetitive motor behaviors are core behavioral phenotypes and are responsive to aripiprazole. Enhanced reward learning and motor responding occurs alongside greater evoked dopamine release. Phenotypes can also vary by sex and show stronger affection in females, an unexpected finding considering males are more frequently affected in TD.

Significance Statement

We generated mouse models that express mutations in high-confidence genes linked to Tourette disorder (TD). These models show sensorimotor and cognitive behavioral phenotypes resembling TD-like behaviors. Sensorimotor gating deficits and repetitive motor behaviors are attenuated by drugs that act on dopamine. Reward learning and striatal dopamine is enhanced. Brain development is grossly normal, including cortical layering and patterning of major axon tracts. Further, no signs of striatal interneuron loss are detected. Interestingly, behavioral phenotypes in affected females can be more pronounced than in males, despite male sex bias in the diagnosis of TD. These novel mouse models with construct, face, and predictive validity provide a new resource to study neural substrates that cause tics and related behavioral phenotypes in TD.

Me, My Tics and I: An Exploration of Self-Identity and its Implications for Psychological Wellbeing in Young Women with Tourette's Syndrome

Women with Tourette's syndrome (TS) continue to be under-researched, despite female sex being associated with increased tic-related impairment in adulthood. Existing literature indicates that individuals with TS are more likely than the general population to report self-stigma, but little is known about the subjective identities of women with TS and how this relates to psychological wellbeing. Semi-structured interviews were conducted via Zoom with a purposive sample of 11 females. All were diagnosed with TS and aged 18-28. Data was transcribed verbatim and thematic analysis applied. Five themes were established: "I'm not normal", "I just want to be me", I'm a "people pleaser", seeing oneself as an "outsider", and "it's just part of me…it's not going anywhere". Difficulties with self-acceptance and the autonomy to be one's true self were noted and appeared to be intensified by stereotypical gender roles and attempts to conceal tics. Findings also suggested that personal growth and feelings of mastery can be achieved through embracing TS as part of one's identity, or recognising it as just one aspect of the self. Psychological support focused on accepting and living with tics rather than reducing them may benefit this population and is currently difficult to access. Consideration should also be given to improving the availability of support groups where women with TS can meet others like themselves.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10882-023-09911-x.

Have We Forgotten What Tics Are? A Re-Exploration of Tic Phenomenology in Youth with Primary Tics

Background

The first systematic description of tics in a large sample was in 1978.

Objectives

To assess the phenomenology of tics in youth and investigate how age and sex influence tic phenomenology.

Methods

Children and adolescents with primary tic disorders have been prospectively included in our Registry in Calgary, Canada, since 2017. We examined tic frequency and distribution using the Yale Global Tic Severity Scale, differences between sexes, and changes in tic severity with age and with mental health comorbidities.

Results

A total of 203 children and adolescents with primary tic disorders were included (76.4% males; mean age = 10.7 years, 95% CI = 10.3-11.1). At first assessment, the most common simple motor tics were eye blinking (57%), head jerks/movements (51%), eye movements (48%) and mouth movements (46%); 86% had at least one simple facial tic. The most frequent complex motor tics were tic-related compulsive behaviors (19%). Throat clearing was the most common simple phonic tic (42%); 5% only had coprolalia. Females had higher frequency and intensity of motor tics than males (P = 0.032 and P = 0.006, respectively), associated with greater tic-related impairment (P = 0.045). Age was positively correlated with the Total Tic Severity Score (coefficient 0.54, P = 0.005), along with the number, frequency and intensity of motor tics but not with their complexity. Psychiatric comorbidities were associated with greater tic severity.

Conclusions

Our study suggests that age and sex affect clinical presentation in youth with tics. The phenomenology of tics in our sample was similar to the 1978 description of tics, and contrasts with functional tic-like behaviors.

Dimensional Assessment of Depression and Anxiety in a Clinical Sample of Adults With Chronic Tic Disorder

OBJECTIVE

Among adults with Tourette syndrome, depression and anxiety symptoms are widely prevalent and consistently associated with poor quality of life. Important knowledge gaps remain regarding mood and anxiety dimensions of the adult Tourette syndrome phenotype. Taking a dimensional approach, this study sought to determine the prevalence, severity, and clinical correlates of depression and anxiety symptoms in a clinical sample of adults with Tourette syndrome and other chronic tic disorders.

METHODS

A retrospective chart review was conducted of all adults with a chronic tic disorder presenting to a tertiary care Tourette syndrome clinic between December 2020 and July 2022. Information extracted during chart review included data from scales administered as part of routine care: Quality of Life in Neurological Disorders (Neuro-QoL) Depression Short Form, Neuro-QoL Anxiety Short Form, Adult Attention-Deficit/Hyperactivity Disorder Self-Report Screening Scale, Dimensional Obsessive-Compulsive Scale, and Yale Global Tic Severity Scale. Relationships between variables were examined by conducting between-group, correlation, and multivariable regression analyses.

RESULTS

Data from 120 adult patients with a chronic tic disorder (77 men and 43 women) were analyzed. Neuro-QoL Anxiety scores were elevated in 66% of the cohort; Neuro-QoL Depression scores were elevated in 26%. Neuro-QoL Anxiety scores were significantly higher than general population norms, whereas Neuro-QoL Depression scores were not. After adjustment for covariates, depressive and anxiety symptom severity scores were significantly associated with each other and with obsessive-compulsive disorder symptom severity but not with tic severity. Sex-based differences emerged in the analyses.

CONCLUSIONS

Among adults with chronic tic disorder, anxiety symptoms were more prevalent and severe than depressive symptoms, co-occurring psychiatric symptoms were more tightly linked with each other than with tic severity, and sex-based differences were evident.

"Unvoluntary" Movement Disorders: Distinguishing between Tics, Akathisia, Restless Legs, and Stereotypies

Tics, stereotypies, akathisia, and restless legs fall at different places on the spectrum of discrete, unwanted and potentially disabling motor routines. Unlike tremor, chorea, myoclonus, or dystonia, this subgroup of abnormal movements is characterized by the subject's variable ability to inhibit or release undesired motor patterns on demand. Though it may be sometimes clinically challenging, it is crucial to distinguish these "unvoluntary" motor behaviors because secondary causes and management approaches differ substantially. To this end, physicians must consider the degree of repetitiveness of the movements, the existence of volitional control, and the association with sensory symptoms, or cognitive-ideational antecedent. This review aims to summarize the current existing knowledge on phenomenology, diagnosis, and treatment of tics, stereotypies, akathisia, and restless leg syndrome.

Oromandibular tics associated with Tourette syndrome

BACKGROUND

Tourette syndrome (TS) is the most common cause of chronic tics. Patients with TS frequently manifest motor tics involving the eyes and face but oromandibular (OM) tics have been rarely studied.

MATERIALS AND METHODS

We reviewed the medical records and video-recordings of 155 consecutive patients with TS in our movement disorders clinic. In addition, we studied 35 patients with classic tardive dyskinesia (TD) and compared their clinical and demographic features with those with TS.

RESULTS

We identified 41 patients with OM tics (26.5%). Although patients with OM tics had a greater overall tic severity and higher frequency of.complex motor and phonic tics, in the bivariate analysis, only comorbid dystonic tics (P = 0.001), greater number of affected body parts (P = 0.012) and more frequent eye-rolling tics (P = 0.059) were included in the final regression model after controlling for other variables. When compared with patients with OM tics, patients with classic TD had more frequently masticatory movements (sensitivity, 0.86; specificity, 0.95), continuous tongue movements (sensitivity, 0.71; specificity, 1.0) and continuous OM movements (sensitivity, 0.4; specificity, 1.0).

CONCLUSIONS

OM tics are common and often troublesome or even disabling symptoms in patients with TS. They may be difficult to differentiate from TD, but the latter is typically manifested by continuous orolingual and masticatory movements.

Tourette syndrome and other tic disorders of childhood

Tics are repetitive, patterned, and nonrhythmic movements or vocalizations/audible sounds that are misplaced in context. Phenomenology and characteristics of tics (e.g., premonitory urge, suppressibility) differentiate them from compulsions, stereotypies, functional tic-like behaviors, and other types of hyperkinetic movement disorders. With a prevalence of approximately 1% in school-aged boys, Tourette syndrome (TS) is considered a common childhood-onset neurodevelopmental disorder, defined by the combination of at least two motor tics and at least one phonic tic lasting more than 1 year. TS is a highly heritable disorder, with a wide spectrum of severity. In some individuals, tics can cause pain, distress, functional impairment, or stigmatization. About 90% of individuals with TS have at least one mental health comorbidity (attention-deficit/hyperactivity disorder, obsessive-compulsive disorder, anxiety/depressive disorders). These comorbidities significantly impact patients' quality of life and must therefore be screened and managed accordingly in this population. Treatment of tics is based on behavioral therapies targeting tics (habit reversal training included in the comprehensive behavioral intervention for tics, and exposure and response prevention for tics), in association with medication if needed (e.g., alpha-2-agonists, second-generation antipsychotics). Deep brain stimulation is considered an experimental option in the most severe, treatment-resistant patients. In adulthood, less than 25% of individuals still have moderate or severe tics.

Childhood Predictors of Long-Term Tic Severity and Tic Impairment in Tourette's Disorder

Tics peak in late childhood and decline during adolescence. Yet, for some with Tourette's disorder, tics persist into adulthood. We evaluated childhood predictors of adult tic severity and tic impairment, and change over time. Eighty adolescents/adults were evaluated 11 years following a randomized-controlled trial of behavior therapy. An independent evaluator rated tic severity and tic impairment at baseline, posttreatment, and long-term follow-up. At baseline, parents completed demographics/medical history, and youth tic, internalizing, and externalizing symptom ratings. Youth rated premonitory urge severity and family functioning. After controlling for prior tic treatment effects, female sex and higher tic severity predicted higher tic severity in adulthood; and female sex, no stimulant medication use, higher tic severity, and poorer family functioning predicted higher tic impairment. Higher tic severity and premonitory urge severity predicted smaller reductions in tic severity, whereas higher externalizing symptoms predicted greater reduction in tic severity. Female sex predicted smaller reduction in tic impairment, and externalizing symptoms predicted greater reduction in tic impairment. Female sex and childhood tic severity are important predictors of tic severity and tic impairment in adulthood. Family functioning, premonitory urge severity, and tic severity are important modifiable targets for early or targeted intervention to improve long-term outcomes.

Diagnosis and Management of Functional Tic-Like Phenomena

Over the past 3 years, a global phenomenon has emerged characterized by the sudden onset and frequently rapid escalation of tics and tic-like movements and phonations. These symptoms have occurred not only in youth known to have tics or Tourette syndrome (TS), but also, and more notably, in youth with no prior history of tics. The Tourette Association of America (TAA) convened an international, multidisciplinary working group to better understand this apparent presentation of functional neurological disorder (FND) and its relationship to TS. Here, we review and summarize the literature relevant to distinguish the two, with recommendations to clinicians for diagnosis and management. Finally, we highlight areas for future emphasis and research.

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

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

Influence of sex on tic severity and psychiatric comorbidity profile in patients with pediatric tic disorder

AIM

To investigate sex-related differences in tic severity, tic-related impairments, and psychiatric comorbidities in childhood.

METHOD

In this cross-sectional study, tic severity/impairment and demographic factors were collected from 270 children and young people (aged 5-17y, mean 10y 6mo, SD 3y 4mo; 212 males and 58 females) with a tic disorder diagnosis at a specialty clinic. Psychiatric diagnoses and corresponding screening questionnaire scores were collected for attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), major depressive disorder, and anxiety disorders. Logistic regression was used to compare the effect of sex and age on psychiatric comorbid diagnoses. The Mann-Whitney U test and t-tests were used to assess differences in questionnaire score distribution between sexes.

RESULTS

Females had more severe motor tics (12.55 vs 10.81, p=0.01) and higher global severity scores (38.79 vs 32.66, p=0.03) on the Yale Global Tic Severity Scale. Females were less likely to be diagnosed with ADHD (odds ratio=0.48, 95% confidence interval=0.26-0.89). No significant sex difference was observed in diagnosis rates or symptom severity scores for anxiety or OCD. Females had significantly higher scores than males on the Children's Depression Inventory, Second Edition.

INTERPRETATION

The higher level of motor tic severity and global severity in females further supports the differential natural history of tic disorders in females. Females with tic disorders may be underdiagnosed for ADHD.

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.

Gut Barrier Dysfunction and Type 2 Immunity: Implications for Compulsive Behavior

To date, much of the focus of gut-brain axis research has been on gut microbiota regulation of anxiety and stress-related behaviors. Much less attention has been directed to potential connections between gut microbiota and compulsive behavior. Here, we discuss a potential link between gut barrier dysfunction and compulsive behavior that is mediated through "type 2" rather than "type 1" inflammation. We examine connections between compulsive behavior and type 2 inflammation in Tourette syndrome, obsessive-compulsive disorder, autism, addiction, and post-traumatic stress disorder. Next, we discuss potential connections between gut barrier dysfunction, type 2 inflammation, and compulsive behavior. We posit a potential mechanism whereby gut barrier dysfunction-associated type 2 inflammation may drive compulsive behavior through histamine regulation of dopamine neurotransmission. Finally, we discuss the possibility of exploiting the greater accessibility of the gut relative to the brain in identifying targets to treat compulsive behavior disorders.

Non-invasive brain stimulation as therapy: systematic review and recommendations with a focus on the treatment of Tourette syndrome

Tourette syndrome (TS) is a neurodevelopmental condition characterised by tics, which are stereotyped movements and/or vocalisations. Tics often cause difficulties in daily life and many with TS express a desire to reduce and/or gain control over them. No singular effective treatment exists for TS, and while pharmacological and behavioural interventions can be effective, the results are variable, and issues relating to access, availability and side effects can be barriers to treatment. Consequently, over the past decade, there has been increasing interest into the potential benefits of non-invasive brain stimulation (NIBS) approaches. This systematic review highlights work exploring NIBS as a potential treatment for TS. On balance, the results tentatively suggest that multiple sessions of stimulation applied over the supplementary motor area (SMA) may help to reduce tics. However, a number of methodological and theoretical issues limit the strength of this conclusion, with the most problematic being the lack of large-scale sham-controlled studies. In this review, methodological and theoretical issues are discussed, unanswered questions highlighted and suggestions for future work put forward.

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.

Fidelity of Delivery and Contextual Factors Influencing Children's Level of Engagement: Process Evaluation of the Online Remote Behavioral Intervention for Tics Trial

Background

The Online Remote Behavioral Intervention for Tics (ORBIT) study was a multicenter randomized controlled trial of a complex intervention that consisted of a web-based behavioral intervention for children and young people with tic disorders. In the first part of a two-stage process evaluation, we conducted a mixed methods study exploring the reach, dose, and fidelity of the intervention and contextual factors influencing engagement.

Objective

This study aims to explore the fidelity of delivery and contextual factors underpinning the ORBIT trial.

Methods

Baseline study data and intervention usage metrics from participants in the intervention arm were used as quantitative implementation data (N=112). The experiences of being in the intervention were explored through semistructured interviews with children (n=20) and parent participants (n=20), therapists (n=4), and referring clinicians (n=6). A principal component analysis was used to create a comprehensive, composite measure of children and young people’s engagement with the intervention. Engagement factor scores reflected relative uptake as assessed by a range of usage indices, including chapters accessed, number of pages visited, and number of log-ins. The engagement factor score was used as the dependent variable in a multiple linear regression analysis with various contextual variables as independent variables to assess if there were any significant predictors of engagement.

Results

The intervention was implemented with high fidelity, and participants deemed the intervention acceptable and satisfactory. The engagement was high, with child participants completing an average of 7.5 of 10 (SD 2.7) chapters, and 88.4% (99/112) of participants completed the minimum of the first four chapters—the predefined threshold effective dose. Compared with the total population of children with tic disorders, participants in the sample tended to have more educated parents and lived in more economically advantaged areas; however, socioeconomic factors were not related to engagement factor scores. Factors associated with higher engagement factor scores included participants enrolled at the London site versus the Nottingham site (P=.01), self-referred versus clinic referred (P=.04), higher parental engagement as evidenced by the number of parental chapters completed (n=111; ρ=0.73; P<.001), and more therapist time for parents (n=111; ρ=0.46; P<.001). A multiple linear regression indicated that parents’ chapter completion (β=.69; t₁₁₀=10.18; P<.001) and therapist time for parents (β=.19; t₁₁₀=2.95; P=.004) were the only significant independent predictors of child engagement factor scores.

Conclusions

Overall, the intervention had high fidelity of delivery and was evaluated positively by participants, although reach may have been constrained by the nature of the randomized controlled trial. Parental engagement and therapist time for parents were strong predictors of intervention implementation, which has important implications for designing and implementing digital therapeutic interventions in child and adolescent mental health services.

International Registered Report Identifier (IRRID)

RR2-10.1186/s13063-019-3974-3

Phakic intraocular lens implantation in a case of Tourette syndrome exacerbated by wearing glasses and contact lenses

A 25-year-old longsighted woman presented with a history of spectacle and contact lens induced exacerbation of Tourette syndrome symptoms. Preoperatively, she had very poor unaided vision (6/60), achieving good (6/9) vision in both eyes with spectacle correction. The patient underwent bilateral simultaneous implantation of phakic implantable collamer lens (ICL) implants (STAAR, USA) which sit in front of the natural lens. Postoperatively, her uncorrected visual acuity was markedly improved as were her manifestations of Tourette syndrome. She achieved her full potential of unaided vision (6/9). This is the first documented case of Tourette syndrome triggered by glasses and contact lenses in which bilateral phakic toric lens implants were effective in improving vision and controlling motor symptoms. Phakic toric ICL implantation is a reversible technique for the correction of visually significant ametropia in selected patients and has improved this patient's quality of life.

Management of Parkinson's disease and other movement disorders in women of childbearing age: Part 2

INTRODUCTION

Many diseases associated with hyperkinetic movement disorders manifest in women of childbearing age. It is important to understand the risks of these diseases during pregnancy, and the potential risks of treatment for the fetus.

OBJECTIVES

This study aims to define the clinical characteristics and the factors affecting the lives of women of childbearing age with dystonia, chorea, Tourette syndrome, tremor, and restless legs syndrome, and to establish guidelines for management of pregnancy and breastfeeding in these patients.

RESULTS

This consensus document was developed through an exhaustive literature search and a discussion of the content by a group of movement disorder experts from the Spanish Society of Neurology.

CONCLUSIONS

We must evaluate the risks and benefits of treatment in all women with hyperkinetic movement disorders, whether pre-existing or with onset during pregnancy, and aim to reduce effective doses as much as possible or to administer drugs only when necessary. In hereditary diseases, families should be offered genetic counselling. It is important to recognise movement disorders triggered during pregnancy, such as certain types of chorea and restless legs syndrome.

The cognitive neuropsychiatry of Tourette syndrome

Introduction: Converging evidence from both clinical and experimental studies has shown that Tourette syndrome (TS) is not a unitary condition, but a cluster of multiple phenotypes, which encompass both tics and specific behavioural and cognitive symptoms (mainly attention-deficit and hyperactivity disorder and obsessive-compulsive disorder). Methods: We conducted a narrative review of the recent literature on the cognitive neuropsychiatry of TS. Results: Although clinical research has shown that TS is not associated with cognitive deficits per se, the findings of recent studies have suggested the presence of subtle alterations in specific cognitive functions. A promising line of research on imitative behaviour could provide a common background for the alterations in executive control and social cognition observed in TS. Two different (but not mutually exclusive) neurocognitive theories have recently suggested that TS could originate from altered perception-action binding and social decision-making dysfunction, respectively. Conclusions: Since the presence of behavioural comorbidities influences individualised treatment approaches, it is likely that a more precise characterisation of TS phenotypes, including cognitive aspects, will result in improved levels of care for patients with tic disorders.

Heterogeneity and Polygenicity in Psychiatric Disorders: A Genome-Wide Perspective

Genome-wide association studies (GWAS) have been performed for many psychiatric disorders and revealed a complex polygenic architecture linking mental and physical health phenotypes. Psychiatric diagnoses are often heterogeneous, and several layers of trait heterogeneity may contribute to detection of genetic risks per disorder or across multiple disorders. In this review, we discuss these heterogeneities and their consequences on the discovery of risk loci using large-scale genetic data. We primarily highlight the ways in which sex and diagnostic complexity contribute to risk locus discovery in schizophrenia, bipolar disorder, attention deficit hyperactivity disorder, autism spectrum disorder, posttraumatic stress disorder, major depressive disorder, obsessive-compulsive disorder, Tourette’s syndrome and chronic tic disorder, anxiety disorders, suicidality, feeding and eating disorders, and substance use disorders. Genetic data also have facilitated discovery of clinically relevant subphenotypes also described here. Collectively, GWAS of psychiatric disorders revealed that the understanding of heterogeneity, polygenicity, and pleiotropy is critical to translate genetic findings into treatment strategies.

Sex and psychiatric comorbidity correlates of the premonitory urge for tic scale in youth with persistent tic disorders

The premonitory urge for tics scale (PUTS) is a common self-report measure of premonitory sensations preceding tics. The present study aimed to examine the internal consistency and concurrent validity of the PUTS by sex and psychiatric comorbidity status; and explored interactions between sex and psychiatric comorbidity in predicting premonitory urge and tic symptom severity. Seventy-four youth and young adults with persistent tic disorders completed the PUTS, while their parents completed the parent tic questionnaire (PTQ) and a demographic measure. Independent samples t-tests revealed no significant sex differences in PUTS items or total score. The PUTS total score also did not significantly differ between participants with and without attention-deficit hyperactivity disorder (ADHD) and/or obsessive-compulsive disorder (OCD) comorbidity. Internal consistency did not significantly differ between females (α = 0.85) and males (α = 0.75), and those with comorbid ADHD and/or OCD (α = 0.83) relative to those without (α = 0.69). With respect to concurrent validity, the PUTS total was significantly correlated with PTQ tic frequency, intensity, number, and severity for males but not for females. Among those with ADHD and/or OCD, the PUTS total score was correlated significantly and strongly with tic number and moderately with tic intensity. Interactions between sex and psychiatric comorbidity performed using 2 × 2 analysis of variance did not significantly predict the PUTS total or PTQ subscale scores. Findings suggest sex and comorbidity status may influence premonitory urge expression. Results have implications for understanding and measurement of the premonitory urge.

Atypical Functional Connectivity in Tourette Syndrome Differs Between Children and Adults

BACKGROUND

Tourette syndrome (TS) is a neuropsychiatric disorder with symptomatology that typically changes over development. Whether and how brain function in TS also differs across development has been largely understudied. Here, we used functional connectivity magnetic resonance imaging to examine whole-brain functional networks in children and adults with TS.

METHODS

Multivariate classification methods were used to find patterns among functional connections that distinguish individuals with TS from control subjects separately for children and adults (N = 202). We tested whether the patterns of connections that classify diagnosis in one age group (e.g., children) could classify diagnosis in another age group (e.g., adults). We also tested whether the developmental trajectory of these connections was altered in TS.

RESULTS

Diagnostic classification was successful in children and adults separately but expressly did not generalize across age groups, suggesting that the patterns of functional connections that best distinguished individuals with TS from control subjects were age specific. Developmental patterns among these functional connections used for diagnostic classification deviated from typical development. Brain networks in childhood TS appeared "older" and brain networks in adulthood TS appeared "younger" in comparison with typically developing individuals.

CONCLUSIONS

Our results demonstrate that brain networks are differentially altered in children and adults with TS. The observed developmental trajectory of affected connections is consistent with theories of accelerated and/or delayed maturation, but may also involve anomalous developmental pathways. These findings further our understanding of neurodevelopmental trajectories in TS and carry implications for future applications aimed at predicting the clinical course of TS in individuals over development.

Sleep difficulties in children with Tourette syndrome and chronic tic disorders: a systematic review of characteristics and associated factors

Sleep difficulties are common in children and young people with Tourette syndrome and chronic tic disorders (TS/CTD). However, it is unclear whether sleep problems can be considered typical of the TS/CTD phenotype or whether they reflect concomitant factors such as individual patient characteristics (e.g. medication use), underlying neurodevelopmental disorders and/or co-occurring psychiatric symptoms. To help address this question, this review systematically explored types and frequency of sleep problems in children and young people with TS/CTD, while also examining the heterogeneity and methodological quality of studies. Psycinfo, Ovid Medline, Embase, and Web of Science databases were searched using a range of terms relating to tics, sleep and co-occurring psychopathology. Studies were considered that included a sample of children with TS/CTD (n &gt; 5) for whom sleep difficulties were measured. Eighteen studies met criteria for inclusion in the review. Findings supported the high prevalence of sleep difficulties in children with TS/CTD, though estimates of sleep difficulties ranged from 9.7% to 80.4%. Twelve studies reported on other factors affecting sleep in this patient group including tic severity, comorbid psychopathological or neurodevelopmental disorders and medication use. Studies varied in terms of methodology, sample characteristics and research quality, but most concluded that children with TS/CTD experienced high levels of sleep difficulties with children with co-occurring anxiety most at risk. The current review highlights the need for further empirical investigation of sleep in children with TS/CTS, with a view to informing understanding and clinical management.

Meta-analysis: Adulthood prevalence of Tourette syndrome

BACKGROUND

Tourette syndrome (TS) is estimated to have a prevalence of 0.30-0.77% in school aged children. Longitudinal studies suggest that roughly half-to-two-thirds of children with TS experience a substantial improvement in tic symptoms during adolescence. By contrast, few studies have examined adulthood prevalence of TS. Accurate prevalence estimates across the lifespan are needed to support regulatory and public health decisions.

METHODS

We searched PubMED and EMBASE for studies that examined the prevalence of TS in adults. We conducted a random-effects meta-analysis of logit event rates to estimate prevalence of TS across studies. Too few studies are available to conduct moderator analysis or examine publication bias. We also examined the risk ratio of TS prevalence in adults for males compared to females.

RESULTS

Three studies involving 2,356,485 participants were included. There were significant differences in TS adulthood prevalence estimates between studies ranging from 49 to 657 cases of TS per million adults. Overall prevalence of TS in adulthood was estimated to be 118 cases of TS per million adults (95%CI: 19-751 cases per million adults). There was a large amount of heterogeneity between studies (I² = 99%) that was likely related to differences in their methods of identification of TS cases. By contrast, the male:female ratio of risk of adulthood TS was similar between studies with a Risk Ratio = 2.33 (95% CI: 1.72-3.16).

CONCLUSION

Estimates of adulthood prevalence of TS are sparse and likely highly affected by differences in method of case identification. Diagnosis and diagnostic estimates of TS could be aided by including a requirement for impairment as well as potential remission criteria similar to other psychiatric conditions.

Sex: A Significant Risk Factor for Neurodevelopmental and Neurodegenerative Disorders

Males and females sometimes significantly differ in their propensity to develop neurological disorders. Females suffer more from mood disorders such as depression and anxiety, whereas males are more susceptible to deficits in the dopamine system including Parkinson's disease (PD), attention-deficit hyperactivity disorder (ADHD) and autism. Despite this, biological sex is rarely considered when making treatment decisions in neurological disorders. A better understanding of the molecular mechanism(s) underlying sex differences in the healthy and diseased brain will help to devise diagnostic and therapeutic strategies optimal for each sex. Thus, the aim of this review is to discuss the available evidence on sex differences in neuropsychiatric and neurodegenerative disorders regarding prevalence, progression, symptoms and response to therapy. We also discuss the sex-related factors such as gonadal sex hormones and sex chromosome genes and how these might help to explain some of the clinically observed sex differences in these disorders. In particular, we highlight the emerging role of the Y-chromosome gene, SRY, in the male brain and its potential role as a male-specific risk factor for disorders such as PD, autism, and ADHD in many individuals.

Sleep Sufficiency in Pediatric and Adolescent Tourette's Disorder: National Survey of Children's Health

OBJECTIVE

The present study compared sleep sufficiency in youth with current Tourette's disorder (TD), history of TD and matched case controls, and examined predictors of sufficient sleep using a large US population-based survey.

METHOD

Participants were 673 caregivers of youth aged 6 to 17 years (298 with current TD, 122 with a history of TD with no endorsement of current diagnosis, and 254 matched case controls) from the 2007 and 2011-2012 versions of the National Survey of Children's Health. History and current TD status, current comorbidity (attention deficit/hyperactivity disorder, anxiety, and depression) and psychiatric medication status were assessed by yes/no items. Current TD severity was dichotomized into mild or moderate/severe symptoms. Sleep was assessed by parent-reported number of sufficient nights their child slept in the past week.

RESULTS

Univariate analysis of variance yielded significant group differences in nights of sufficient sleep (F[2,369.70] = 71.53, p < .001), with controls having 1.5 more nights per week relative to both TD groups (p < .001). With respect to predictors of sufficient sleep, the analysis of covariance yielded a significant age × sex × TD severity interaction (F[1,15.84] = 4.28, p = .04) such that older adolescent males with mild TD had significantly fewer nights of sufficient sleep than children (p = .004) and early adolescents (p = .002; F[2,54.93] = 7.45, p = .001). Early adolescent females with moderate/severe TD had fewer nights of sufficient sleep relative to males (p = .008). Comorbidity type and psychiatric medication status did not significantly predict sleep.

CONCLUSION

Findings suggest that insufficient sleep in youth with TD persists independently of comorbidity or psychiatric medication status. Findings highlight the importance of clinical sleep monitoring in this population.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Tourette syndrome research highlights 2015

We present selected highlights from research that appeared during 2015 on Tourette syndrome and other tic disorders. Topics include phenomenology, comorbidities, developmental course, genetics, animal models, neuroimaging, electrophysiology, pharmacology, and treatment. We briefly summarize articles whose results we believe may lead to new treatments, additional research or modifications in current models of TS.

Inhibition, Disinhibition, and the Control of Action in Tourette Syndrome

Tourette syndrome (TS) is a neurological disorder characterized by vocal and motor tics. TS is associated with impairments in behavioral inhibition, dysfunctional signaling of the inhibitory neurotransmitter GABA, and alterations in the balance of excitatory and inhibitory influences within brain networks implicated in motor learning and the selection of actions. We review evidence that increased control over motor outputs, including the suppression of tics, may develop during adolescence in TS and be accompanied by compensatory, neuromodulatory, alterations in brain structure and function. In particular, we argue that increased control over motor outputs in TS is brought about by local increases in 'tonic' inhibition that lead to a reduction in the 'gain' of motor excitability.

Structural Connectivity in Gilles de la Tourette Syndrome

Investigators from Centre de Reference National Maladie Rare ‘Syndrome Gilles de la Tourette’ and Sorbonne University report white matter abnormalities in the pathways connecting the cerebral cortex, basal ganglia, and thalamus in a group of 49 adults with Tourette syndrome (TS).

Tourette Syndrome research highlights 2014

About 200 journal articles reported research on Tourette syndrome and other tic disorders in 2014. Here we briefly summarize a few of the reports that seemed most important or interesting, ranging from animal models to human studies. Readers can comment on our choices or provide their own favorites using the tools on the online article.