Functional Tic-Like Behaviors: A Common Comorbidity in Patients with Tourette Syndrome.

BACKGROUND: Comorbid functional tic-like behaviors (FTB) have been described only rarely in patients with Tourette syndrome (TS). OBJECTIVES: We present the first large sample of patients suffering from TS and FTB to raise awareness of this clinical presentation and to guide how to differentiate one from the other. METHODS: We analyzed clinical data of 71 patients (n = 27 [38.0%] female, mean age: 21.5, range: 11-55) with TS + FTB. RESULTS: In the majority of patients, FTB started abruptly on average 15 years after tic onset with "treatment-resistant" complex movements and ("coprophenomena-like") vocalizations preceded by timely related psychological stressors. Psychological evaluation revealed evidence for internal conflicts (79%), emotional dysregulation (56%), and maintaining factors (70%). About one third of patients had a positive history for further medically unexplained symptoms. Compared to a large TS sample (n = 1032), patients with TS + FTB were more likely to be female, and presented significantly more common with "coprophenomena-like" symptoms, atypical influential factors, atypical descriptions of premonitory sensations, and higher rates of comorbid obsessive-compulsive disorder and "self-injurious" behavior. CONCLUSIONS: Based on our data it can be assumed that FTB is a common comorbidity in TS, similar to functional overlay in other movement disorders and epilepsy. Before classifying a patient as suffering from treatment-resistant TS, FTB should be ruled out.

Developmental stuttering, physical concomitants associated with stuttering, and Tourette syndrome: A scoping review.

BACKGROUND AND PURPOSE: Developmental stuttering and Tourette syndrome (TS) are common neurodevelopmental disorders. Although disfluencies may co-occur in TS, their type and frequency do not always represent pure stuttering. Conversely, core symptoms of stuttering may be accompanied by physical concomitants (PCs) that can be confused for tics. This scoping review aimed to explore the similarities and differences between stuttering and tics in terms of epidemiology, comorbidities, phenomenology, evolution, physiopathology, and treatment. We also described the nature of PCs in stuttering and disfluencies in TS. METHODS: A literature search on Medline, Embase and PsycInfo was executed in March 2022. From 426 studies screened, 122 were included in the review (a majority being narrative reviews and case reports). RESULTS: TS and stuttering have several epidemiological, phenomenological, comorbidity, and management similarities suggesting shared risk factors and physiopathology (involving the basal ganglia and their connections with speech and motor control cortical regions). PCs in stuttering commonly involve the face (eyelids, jaw/mouth/lip movements) and sometimes the head, trunk and limbs. PCs can be present from early stages of stuttering and vary over time and within individuals. The function of PCs is unknown. Some individuals with TS have a distinct disfluency pattern, composed of a majority of typical disfluencies (mostly between-word disfluencies), and a mix of cluttering-like behaviors, complex phonic tics (e.g. speech-blocking tics, echolalia, palilalia), and rarely, atypical disfluencies. CONCLUSION: Future investigations are warranted to better understand the complex relationships between tics and stuttering and address the management of disfluencies in TS and PCs in stuttering.

Functional tics: Expanding the phenotypes of functional movement disorders?

BACKGROUND AND PURPOSE: Until the outbreak reported during the COVID-19 pandemic, functional tics were considered to be a relatively rare clinical phenotype, as opposed to other functional movement disorders such as functional tremor and dystonia. To better characterize this phenotype, we compared the demographic and clinical characteristics of patients who developed functional tics during the pandemic and those of patients with other functional movement disorders. METHODS: Data from 110 patients were collected at the same neuropsychiatry centre: 66 consecutive patients who developed functional tics without other functional motor symptoms or neurodevelopmental tics and 44 patients with a mix of functional dystonia, tremor, gait, and myoclonus. RESULTS: Both groups were characterized by female sex preponderance (70%-80%) and (sub)acute onset of functional symptoms (~80%). However, patients with functional tics had a significantly earlier age at onset of functional symptoms (21 vs. 39 years). Exposure to relevant social media content was reported by almost half of the patients with functional tics, but by none of the patients with other functional movement disorders. Comorbidity profiles were similar, with relatively high rates of anxiety/affective symptoms and other functional neurological symptoms (nonepileptic attacks). CONCLUSIONS: Patients who developed functional tics during the pandemic represent a phenotypic variant of the wider group of patients with functional movement disorders, associated with younger age at onset and influenced by pandemic-related factors, including increased exposure to specific social media content. Diagnostic protocols and treatment interventions should be tailored to address the specific features of this newly defined phenotype.

Neurodevelopmental versus functional tics: A controlled study.

BACKGROUND: An unprecedented increase in newly developed functional tics, mainly in young females, has been reported during the COVID-19 pandemic. We set out to complement existing case series with the largest controlled study to date on the clinical phenomenology of functional tics versus neurodevelopmental tics. METHODS: Data from 166 patients were collected at a specialist clinic for tic disorders during a three-year period overlapping with the COVID-19 pandemic (2020-2023). We compared the clinical features of patients who developed functional tics during the COVID-19 pandemic (N = 83) to patients with Tourette syndrome matched for age and gender (N = 83). RESULTS: Female adolescents and young adults accounted for 86% of the clinical sample of patients with functional tics, who were less likely to report a family history of tic disorders than their matched controls with Tourette syndrome. Co-morbidity profiles were significantly different: anxiety and other functional neurological disorders were more strongly associated with functional tics, whereas attention-deficit and hyperactivity disorder and tic-related obsessive-compulsive behaviors co-occurred more frequently with neurodevelopmental tics. Overall, absence of tic-related obsessive-compulsive behaviors (t = 8.096; p < 0.001) and absence of a family history of tics (t = 5.111; p < 0.001) were the strongest predictors of the diagnosis of functional tics. Compared to neurodevelopmental tics, functional tics were more likely to present acutely/subacutely at a later age (21 versus 7 years), without a clear rostro-caudal progression. Coprophenomena, self-injurious behaviors, and complex clinical manifestations such as blocking tics, throwing tics, and tic attacks, were all over-represented in the functional group. CONCLUSIONS: Our findings provide robust confirmation of both patient-related variables and tic characteristics contributing to the differential diagnosis between functional tics developed during the pandemic and neurodevelopmental tics reported by patients with Tourette syndrome.

Symptoms compatible with long COVID in an Italian pediatric cohort of Tourette patients with and without SARS­CoV­2 infection: a short-term follow-up assessment.

BACKGROUND: Tourette Syndrome (TS) is a childhood-onset neurodevelopmental disorder with a worldwide prevalence of about 0.3-1% of the population. During the pandemic caused by SARS-CoV-2 infection, the impact on the mental health of children and adolescents was very important. The persistence of symptoms in the post-acute phase of the disease has been termed Long COVID. The neuropsychiatric symptoms seem to be the most common impairment in children and adolescents with long COVID. OBJECTIVES: Considering the impact of pandemic on mental health, in this study we analyzed the long-term effects of SARS-CoV-2 infection in children and adolescents affected by TS. METHODS: We conducted an online questionnaire covering socio-demographic and clinical data among 158 patients affected by TS or chronic tic disorders (CTD), of which 78 participants reported a positive SARS-CoV-2 infection. Data were collected to investigate tic severity and both the comorbidities, as well as lockdown-related changes to daily life activities and, in case of infection of SARS-CoV-2, possible symptoms of acute infection and long COVID. Markers of systemic inflammation including C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), ferritin, iron, electrolytes, white blood cell counts, platelet cell counts levels, markers of liver, kidney and thyroid function were analyzed. First, all patients were screened with the Schedule for affective disorders and Schizophrenia for School age children-present and lifetime (Kiddie-SADS-PL) to rule out primary psychiatric disorders considered as criteria of exclusion. Then, all patients were clinically assessed at baseline (T0), and after three months (T1) through the administration of Yale Global Tic Severity Rating Scale (YGTSS), Multidimensional Anxiety Scale for Children (MASC), Child Depression Inventory (CDI) and Child Behavior Checklist (CBCL). RESULTS: Among the cohort of TS patients that contracted SARS-CoV-2 infection, 84.6% (n = 66) experienced any acute symptoms, and long COVID symptoms occurred in 38.5% (n = 30). A worsening of clinical symptoms of tics and eventually associated comorbidities occurred in 34.6% (n = 27) of TS patients that contracted SARS-CoV-2 infection. TS patients with or without SARS-CoV-2 infection showed an increase in the severity of tics and also behavioral, depressive and anxious symptoms. Instead, this increase was more evident in patients who contracted the infection than in patients who did not contract it. CONCLUSIONS: SARS-CoV-2 infection may have a role in the increase of tics and associated comorbidities in TS patients. Despite of these preliminary results, further investigations are necessary to improve knowledge about the acute and long-term impact of SARS-CoV-2 in TS patients.

New-onset functional tics during the COVID-19 pandemic: Clinical characteristics of 105 cases from a single centre.

BACKGROUND AND PURPOSE: The COVID-19 pandemic has been associated amongst other things with a sharp increase in adolescents and young adults presenting acutely with functional tics. Initial reports have suggested clinically relevant differences between functional tics and neurodevelopmental tics seen in primary tic disorders such as Tourette syndrome. We aimed to provide confirmatory findings from the largest single-centre cohort to date. METHODS: In the present study we present data from 105 consecutive patients who developed functional tics during a 3-year period overlapping with the COVID-19 pandemic (April 2020-March 2023). All patients underwent a comprehensive neuropsychiatric assessment at a single specialist centre for tic disorders. RESULTS: Female adolescents and young adults accounted for 69% of our sample. Functional tics had an acute/subacute onset in most cases (75% with a peak of severity within 1 month). We found a disproportionately high frequency of complex movements (81%) and vocalizations (75%). A subset of patients (23%) had a pre-existing primary tic disorder (Tourette syndrome with functional overlay). The most common psychiatric co-morbidities were anxiety (70%) and affective disorders (40%). Moreover, 41% of patients had at least one functional neurological disorder in addition to functional tics. Exposure to tic-related social media content was reported by half of the patients. CONCLUSIONS: Our findings confirm substantial clinical differences between functional tics developed during the pandemic and neurodevelopmental tics. Both patient- and tic-related red flags support the differential diagnostic process and inform ongoing monitoring in the post-pandemic era.

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.

Sociodemographic and clinical characteristics of children with tic disorders and behavioral problems: A real-world study and development of a prediction model.

BACKGROUND: Tic disorders (TD) are complex neuropsychiatric disorders frequently associated with a variety of comorbid problems, whose negative effects may exceed those of the tics themselves. In this study, we aimed to explore the sociodemographic and clinical characteristics of children with TD and behavioral problems, and develop a prediction model of behavioral problems based on the predictors under real-world conditions. METHODS: A hospital-based cross-sectional study was conducted on children with TD. Behavioral problems were surveyed using the Achenbach Child Behavior Checklist (CBCL). Sociodemographic information was collected from face-to-face interviews using an electronic questionnaire administered during the initial ambulatory visit. Clinical data were collected from medical records, and quality control was performed. The sociodemographic and clinical characteristics of patients with and without behavioral problems were statistically compared, and a nomogram prediction model was developed based on multivariate logistic regression analysis. The discriminatory ability and clinical utility of the nomogram were assessed by concordance index (C-index), receiver operating characteristic (ROC) curve, decision curve analysis (DCA) and clinical impact curve (CIC). RESULTS: A total of 343 TD cases were included in the final analysis, of which 30.32% had behavioral problems. The prediction model showed age 12-16 years, abnormal birth history, parenting pattern of indulgence, parent/close relatives with psychiatric disorders, chronic motor or vocal tic disorder (CTD)/Tourette syndrome (TS) and moderate/severe tic severity were associated with behavioral problems in children with TD. The C-index of the prediction model (nomogram) was 0.763 (95% confidence interval, 0.710 ~ 0.816). The nomogram was feasible for making beneficial clinical decisions, according to the satisfactory results of the DCA and CIC. CONCLUSIONS: A nomogram prediction model for comorbid behavioral problems in children with TD was established. The prediction model demonstrated a good discriminative ability and predictive performance for beneficial clinical decisions. This model further provides a comprehensive understanding of associated sociodemographic and clinical characteristics by visual graphs and allows clinicians to rapidly identify patients with a higher risk of behavioral problems and tailor necessary interventions to improve clinical outcomes.

An approach for prevention planning based on the prevalence and comorbidity of neurodevelopmental disorders in 6-year-old children receiving primary care consultations on the island of Menorca.

BACKGROUND: Few studies have estimated the real prevalence of neurodevelopmental disorders according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) in Spain and worldwide. However, there are disparate prevalence figures. We consider research in this field essential to improve early detection, secondary prevention, and health planning. METHODS: The Minikid ADHD and TICS-Mini International Neuropsychiatric Interview for Children and Adolescents, the Autism Spectrum Quotient (Children's version, AQ- Child) and a protocol of general medical questions were administered for screening purposes. The PROLEXIA battery for children aged from 4 to 6 years was used for direct assessments. Parents provided information on emotional, medical, and school aspects. The final population evaluated using these tools consisted of 291 6-year-old subjects. RESULTS: The overall risk of presenting with a neurodevelopmental disorder was 55.4%. A 23.4% risk of presenting with attention-deficit/hyperactivity disorder (ADHD) in any modality (inattentive, hyperactive-impulsive and combined), a 2.8% risk of developing autism spectrum disorder (ASD), a 30.6% risk of presenting with a learning disorder with reading difficulties, a 5.5% risk of tics and a 22.5% risk of language problems (incomprehensible language or minor language problems) were detected in the sample. The most common combination of disorders was learning and language difficulties, accounting for 6.9% of the sample. The second most frequent combination was the presence of learning and language difficulties and ADHD, accounting for 4.5% of the sample. CONCLUSIONS: The prevalence of risks detected in our sample seems to be consistent with national and international studies. A significant proportion of our sample had never been previously diagnosed (85%), so early detection programs are recommended.

Impact of Tourette Syndrome on Education.

BACKGROUND: Previous studies have shown that Tourette syndrome (TS) has an impact on academic achievements. The aim of this study was to investigate the association between the severity of tics and comorbidities and educational outcomes. METHODS: From 2005 to 2007, 395 participants were included in a large cohort (314 with TS and 81 controls) and the mean age was 12.60 ± 2.64 years. The cohort was re-examined after 4 to 8 years (median 5.6) where n = 276 participants (223 with TS and 53 controls) were included with a mean age of 18.52 ± 2.73 years. At both time points, severity of tics and the presence and severity of psychiatric comorbidity were assessed. Educational achievements were assessed through structured interviews. RESULTS: Children with TS had a lower passing rate at lower secondary and high school compared to healthy controls. More severe vocal tics were associated with fewer passing lower secondary school at a prospective level. At a cross-sectional level, more severe motor tics were associated with fewer passing high school. Tic severity only influenced children with TS without comorbidity. The severity of comorbidity was found to be associated with the educational level at a longitudinal view, but not cross-sectional. CONCLUSION: Overall, children with TS had a lower passing rate at lower secondary school and high school compared to healthy controls. We found that this difference was more likely driven by the severity of comorbidities than tic severity. It is important to be aware of academic achievement in children with TS in order to give them the right support and thereby optimize educational opportunities.

Polygenic and environmental determinants of tics in the Avon Longitudinal Study of Parents and Children.

Tourette syndrome (TS) is caused by multiple genetic and environmental factors. Yet, little is known about the interplay of these factors in the occurrence of tics. We investigated whether polygenic risk score (PRS) of TS and pregnancy-related factors together enhance the explained variance of tic occurrence in the Avon Longitudinal Study of Parents and Children (Ncases  = 612; Ncontrols  = 4,201; 50% male; mean age 13.8 years). We included a cumulative adverse pregnancy risk score, maternal anxiety and depression, and maternal smoking and alcohol use during pregnancy. We investigated possible joint effects of genetic and pregnancy-related risk factors using a multivariable approach, and explored mediation effects between the pregnancy-related risk factors in explaining tic presence. The PRS and the cumulative adverse pregnancy risk score, maternal anxiety, or maternal depression explained significantly more variance of tic presence compared to models including only the PRS. Furthermore, we found that the cumulative adverse pregnancy risk score mediated the association between several pregnancy-related factors (maternal anxiety, depression, and smoking) and tics. The combination of a PRS and pregnancy-related risk factors explained more variance of tics in a general population cohort compared to studying these factors in isolation.

Increased Number of Functional Tics Seen in Danish Adolescents during the COVID-19 Pandemic.

BACKGROUND: Global increase in functional tics in adolescents has been observed. Differentiating functional from classic tics is important since pathophysiology and treatment differ. We investigated possible triggers for development of functional tics and discuss the possible role of the coronavirus disease 2019 (COVID-19) pandemic and social media exposure in cases of functional tics seen during this period. Moreover, the treatment, and its efficacy is discussed. METHODS: Medical records of 28 Danish adolescents diagnosed with functional tics at the National Tourette Clinic, Department of Pediatrics, Herlev University Hospital, Denmark, from May 2020 to June 2021 have been retrospectively reviewed. Descriptive statistical analyses were used to analyze the data. MAIN FINDINGS: A total of 28 patients diagnosed with functional tics were included, 96.4% girls and 3.6% boys, mean age 14.4 years. Tic phenomenology differed from classic tics with more complex tics and no rostrocaudal progression. Note that 69.2% reported harmful tics. Also, 78.6% had trauma/precipitating event and 40% denounced lockdown related to the COVID-19 pandemic as trigger, both prior to onset of functional tics. Note that 60.7% reported psychiatric symptoms/diagnoses, 42.9% had a first-degree family member with psychiatric symptoms/diagnoses, and 96.4% were exposed to tics on social media prior to onset. Treatment consisted of psychoeducation, elements from cognitive behavioral therapy, and focus on psychiatric symptoms. All patients responded to the treatment. CONCLUSION: The vulnerability of the adolescents is characteristic. Treatment strategy has shown immediate positive effect. Consequences of the COVID-19 pandemic in combination with exposure to tics on social media could be part of the cause for the increase in number of functional tics.

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.

Antiseizure medication-induced obsessive-compulsive disorder and tic disorder: a pragmatic review.

INTRODUCTION: With a lifetime prevalence of 2.3%, obsessive compulsive disorder is a chronic, disabling condition that is associated with significant social and occupational impairment. Up to 30% of individuals with obsessive-compulsive disorder have a lifetime diagnosis of tic disorders. Antiseizure medication is increasingly used for a variety of physical and psychiatric illnesses. Clarification of the relationship between these symptoms/disorders and use of antiseizure medication is critically important for diagnostic and treatment purposes. AREAS COVERED: Studies on antiseizure-induced obsessive-compulsive disorder and tic disorders are reviewed. The literature search strategy identified 89 articles. Twenty-nine articles were included in the final results. Of these, 24 are case reports or case studies, 2 cross-sectional studies, 1 chart review, 1 population-based case-control study and 1 observational prospective study assessing lamotrigine, levetiracetam, topiramate, zonisamide, and carbamazepine. EXPERT OPINION: This study highlighted the temporal relationship of antiseizure medication use and onset of obsessive-compulsive symptoms and tics. Monitoring for medication-induced obsessive compulsions or tics should be undertaken when prescribing antiseizure medication for treatment of mood disorders or epilepsy. Further research identifying the causal relationship between antiseizure medication and de novo onset of obsessive-compulsive symptoms, obsessive-compulsive disorder and tic disorder is required.

A prospective clinical cohort-based study of the prevalence of OCD, obsessive compulsive and related disorders, and tics in families of patients with OCD.

BACKGROUND: The lifetime prevalence of obsessive - compulsive disorder (OCD) is currently estimated at 2 - 3% and the prevalence in first-degree family members is estimated to range between 10 and 11%. Separating OCD from other anxiety disorders and including it into the new "obsessive - compulsive and related disorders" (OCRDs) category has had a dramatic impact on the diagnosis, while also contributing to the better understanding of the genetics of these disorders. Indeed, grouping OCD with body dysmorphic disorder (BDD), and body-focused repetitive behaviors such as trichotillomania (hair pulling), onychophagia (nail biting), and excoriation (skin picking) into the same diagnostic family has resulted in a much greater lifetime prevalence (> 9%). These diagnostic changes necessitate an updated epidemiological study, thus motivating this investigation. METHODS: The study sample comprised of 457 patient's cases from an Israeli and an Australian OCD center. Interviews were completed as a part of the intake or during treatment in each of the centers. Prevalence of OCD, OCRDs, tics, and other psychiatric comorbidities in first- and second-degree relatives was assessed by interviewing the OCD patients. Interviews were conducted by at least two researchers (LC, OBA, JZ) and only family information on which the interviewers have reached consensus was considered. RESULTS: Initial analyses revealed an increase of OCD and OCRD prevalence in first- and second-degree family members as compared to the current literature due to reclassification of these disorders in DSM-5. CONCLUSION: The new category of OCRD has changed the landscape of epidemiological studies in OCD. Further and broader studies are needed in order to better understand the lifetime prevalence of OCRD in first- and second-degrees family member.

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

BACKGROUND AND OBJECTIVES: The goal of this work was to investigate the association between group A streptococcal (GAS) infections and tic incidence among unaffected children with a family history of chronic tic disorders (CTDs). METHODS: In a prospective cohort study, children with no history for tics who were 3 to 10 years of age with a first-degree relative with a CTD were recruited from the European Multicentre Tics in Children Study (EMTICS) across 16 European centers. Presence of GAS infection was assessed with throat swabs, serum anti-streptolysin O titers, and anti-DNAse titers blinded to clinical status. GAS exposure was defined with 4 different definitions based on these parameters. Cox regression analyses with time-varying GAS exposure were conducted to examine the association of onset of tics and GAS exposure during follow-up. Sensitivity analyses were conducted with Cox regression and logistic regression analyses. RESULTS: A total of 259 children were recruited; 1 child was found to have tic onset before study entry and therefore was excluded. Sixty-one children (23.6%) developed tics over an average follow-up period of 1 (SD 0.7) year. There was a strong association of sex and onset of tics, with girls having an ≈60% lower risk of developing tics compared to boys (hazard ratio [HR] 0.4, 95% confidence interval [CI] 0.2-0.7). However, there was no statistical evidence to suggest an association of any of the 4 GAS exposure definitions with tic onset (GAS exposure definition 1: HR 0.310, 95% CI 0.037-2.590; definition 2: HR 0.561, 95% CI 0.219-1.436; definition 3: HR 0.853, 95% CI 0.466-1.561; definition 4: HR 0.725, 95% CI 0.384-1.370). DISCUSSION: These results do not suggest an association between GAS exposure and development of tics. CLASSIFICATION OF EVIDENCE: This study provides Class I evidence that group A streptococcal exposure does not associate with the development of tics in children with first-degree relatives with chronic tic disorder.

[Significantly increased incidence of functional tics among children and adolescents].

During 2020, an increase of functional tics in children and adolescents has been observed. In this review, we present phenotypes, differential diagnosis and treatment for functional tics. We discuss potential contributing causes, like the COVID-19 pandemic and the focus on tics on social media. Functional tics are more complex than tics seen in Tourette syndrome and develop more suddenly in relation to stressors mainly in teenage girls. Psychosocial issues and comorbidities must be addressed and treated by a multidisciplinary team through psychoeducation and if necessary, cognitive-behavioural therapy.

Multivariate Classification of Brain Blood-Oxygen Signal Complexity for the Diagnosis of Children with Tourette Syndrome.

Tourette syndrome (TS) is a childhood-onset neuropsychiatric disorder characterized by the presence of multiple motor and vocal tics. Because of its varied clinical expressions and lack of reliable diagnostic biomarker, present TS diagnosis still depends on qualitative descriptions of symptoms. Our study aimed to investigate whether the complexity of resting state brain activity can serve as a potential biomarker for TS diagnosis, since it has been used successfully in various neuropsychiatric disorders, including two common TS comorbidities: attention-deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD). In the current study, we used both univariate analysis and multivariate searchlight analysis with both linear and non-linear classification methods to explore the group differences in the complexity of resting state brain blood oxygen level-dependent (BOLD) signals between 25 TS boys without comorbidity and 25 sex, age and educational years matched healthy controls (HCs). We also investigated the relation between symptom severity in TS patients (YGTSS scores) and complexity indices derived from different analysis methods. We found: i) univariate analysis revealed reduced complexity in TS patients in the left cerebellum, left superior frontal gyrus, and left medial frontal gyrus; ii) multivariate analysis with non-linear classification method achieved the highest performance (accuracy: 0.94, sensitivity: 0.96, specificity: 0.92, AUC: 0.95) in bilateral supplementary motor areas; iii) significant correlations were found between complexity index derived from multivariate analysis with non-linear classification method and Tic severity (YGTSS scores) in the left cerebellum (r = 0.523, with YGTSS phonic) and in the right supplementary motor area (r = 0.767, with YGTSS motor). Taken together, these results suggested that complexity of resting state BOLD activity is a highly effective index for differentiating TS patients from normal controls. It has a good potential to be a quantitative biomarker for TS diagnosis.