Tourette Research Articles

Thalamic deep brain stimulation for tourette syndrome increases cortical beta activity

BackgroundDeep brain stimulation (DBS) of the thalamus can effectively reduce tics in severely affected patients with Tourette syndrome (TS). Its effect on cortical oscillatory activity is currently unknown. ObjectiveWe assessed whether DBS modulates beta activity at fronto-central electrodes. We explored concurrent EEG sources and probabilistic stimulation maps. MethodsResting state EEG of TS patients treated with thalamic DBS was recorded in repeated DBS-on and DBS-off states. A mixed linear model was employed for statistical evaluation. EEG sources were estimated with eLORETA. Thalamic probabilistic stimulation maps were obtained by assigning beta power difference scores (DBS-on minus DBS-off) to stimulation sites. ResultsWe observed increased beta power in DBS-on compared to DBS-off states. Modulation of cortical beta activity was localized to the midcingulate cortex. Beta modulation was more pronounced when stimulating the thalamus posteriorly, peaking in the ventral posterior nucleus. ConclusionThalamic DBS in TS patients modulates beta frequency oscillations presumably important for sensorimotor function and relevant to TS pathophysiology.

The Association of Quality of Life with Psychosocial Factors in Adolescents with Tourette Syndrome.

Individuals with Tourette syndrome (TS) have poorer quality of life (QoL) than their peers, yet factors contributing to poor QoL in this population remain unclear. Research to date has predominantly focused on the impact of tics and psychiatric symptoms on QoL in TS samples. The aim of this cross-sectional, multi-informant study was to identify psychosocial variables that may impact adolescent QoL in TS. Thirty-eight adolescents aged 13 to 17 with TS and 28 age-matched controls participated with a caregiver. No group differences were found on QoL, although the TS group reported reduced QoL compared to population normative data. In the TS group, reduced QoL was associated with lower self-esteem, poorer family functioning, higher stress, and greater depression and anxiety; QoL was unrelated to tic severity. In regression analyses, after adjusting for covariates, family functioning was the strongest predictor of QoL. These results emphasize the need to further explore the influence of psychosocial factors, particularly family functioning, on QoL in adolescents with TS.

Tourette Syndrome and Tic Disorders.

Tourette Syndrome and Tic Disorders.

Neurotransmitter regulation as common pathways between sleep phenotypes, restless leg syndrome and Tourette syndrome

Neurotransmitter regulation as common pathways between sleep phenotypes, restless leg syndrome and Tourette syndrome

Perspectives from Adults with Tourette Syndrome on Research Priorities and Registry Development: A Focus Group Study.

Adults with Tourette syndrome (TS) have worse mental health, physical health, and quality of life than the general population. The factors contributing to negative outcomes across multiple health domains in adults with TS remain uncertain, in part due to a lack of longitudinal studies in this population. In attempt to address these knowledge gaps, our center has initiated development of a regional registry for adults with TS. During the goal-setting and design phase of registry development, we conducted focus groups with adults with TS to identify research issues of greatest importance to this population and to obtain feedback on design and implementation of an adult TS registry. Participants were recruited from a tertiary care adult TS clinic and from institutional research registries. Focus groups were conducted online and were moderated by a qualitative research expert. Qualitative data analysis was performed using an iterative inductive/deductive approach. Across four focus groups, adult TS participants (n=22) expressed a variety of research priorities, including developing more effective treatments for tics, identifying risk factors for tic persistence into adulthood, clarifying the interaction between TS symptoms and women's health, clarifying the relationships between TS and other mental and physical health disorders, and addressing day-to-day living issues. Focus group participants were generally enthusiastic about creation of an adult TS registry. They indicated that adults with TS are more likely to engage with a registry that logistically accommodates participants (eg, by offering a wide range of visit times, by providing telehealth options) and that fosters bidirectional interaction (eg, by disseminating results regularly, by involving participants in registry design and implementation, by notifying participants of support resources). Focus group input clarifies the research priorities of adults with TS and will inform the ongoing development of an adult TS registry.

Temperament Traits in Pediatric Obsessive-Compulsive Disorder in Relation to Tourette Syndrome and Attention-Deficit Hyperactivity Disorder

Introduction: Pediatric obsessive-compulsive disorder (OCD), attention-deficit hyperactivity disorder (ADHD), and Tourette syndrome (TS) are often concurrent. This study explores the temperament profile of complex OCD phenotypes. Methods: A clinical registry recorded demographic data, psychiatric diagnoses, and temperament traits, including novelty seeking (exploratory behaviors), harm avoidance (fear of uncertainty), reward dependence (sentimentality), and persistence (perseverance). Temperament data were accrued from the Junior Temperament and Character Inventory (JTCI). Participants were divided into (1) OCD only; (2) OCD+ADHD or TS; and (3) OCD+ADHD+TS to compare temperament. Results: Participants include 126 youths with OCD (61.9% male, 88.9% white) between the ages 6 and 18 years (12.7 ± 3.1). Among the three groups, the complex neurodevelopmental disorder group OCD+ADHD+TS expresses the highest novelty seeking and lowest persistence. Harm avoidance is increased in all groups compared to reference controls, irrespective of concurrent ADHD or TS. For the OCD+ADHD+TS group, contamination and washing symptoms have higher novelty seeking (p < 0.01), while counting and ordering have lower novelty seeking (p < 0.05). Harm avoidance is increased with aggressive, somatic, and checking symptoms in OCD only (p < 0.01), while persistence is increased with repeating and counting symptoms in the comorbid groups (OCD+ADHD or TS, OCD+ADHD+TS). Discussion/Conclusion: The complex subtype, OCD+ADHD+TS, is associated with high novelty seeking and low persistence, while high harm avoidance is linked to pediatric OCD irrespective of ADHD or TS co-occurrence. In sum, pediatric OCD with ADHD and TS confers a unique temperament profile, further refining complex phenotypes of pediatric OCD for future research.

The use of deep brain stimulation in treatment-refractory Tourette syndrome - a literature review

The use of deep brain stimulation in treatment-refractory Tourette syndrome - a literature review

Theory of mind in neurodevelopmental disorders: beyond autistic spectrum disorder

IntroductionTheory of mind (ToM) is the human ability to perceive, interpret, and attribute the mental states of other people, and the alteration of this cognitive function is a core symptom of autistic spectrum disorder (ASD). In such other neurodevelopmental disorders as childhood-onset obsessive-compulsive disorder (OCD) and Tourette syndrome (TS) that can present with cognitive dysfunctions, ToM has been less extensively studied, especially in the young population. The aim of the study was to compare advanced ToM between groups of young people diagnosed with OCD, TS, or ASD and a control group. MethodsClinical interviews were conducted with male patients aged between 11 and 17 years with a main diagnosis of OCD (n = 19), TS (n = 14), or ASD (n = 18), and a control group (n = 20). We administered instruments for estimating intelligence quotient and severity of psychiatric symptoms, and tasks to evaluate ToM (the "Stories from everyday life" task and the "Reading the mind in the eyes” test). ResultsYoung people with TS and with ASD present similar difficulties in solving advanced ToM tasks, whereas patients with childhood-onset OCD present similar results to controls. ConclusionsToM is altered in other neurodevelopmental disorders beyond ASD, such as TS.

The Effect of Nabiximols on Driving Ability in Adults with Chronic Tic Disorders: Results of a Substudy Analysis of the Double-Blind, Randomized, Placebo-Controlled CANNA-TICS Trial.

Background: The multicenter, randomized, double-blind, parallel-group, phase IIIb CANNA-TICS (CANNAbinoids in the treatment of TICS) trial showed clear trends for improvement of tics, depression, and quality of life with nabiximols versus placebo in adult patients with Gilles de la Tourette syndrome and other chronic tic disorders. Although in general nabiximols was well tolerated, it is unclear whether treatment using this cannabis extract influences driving skills in patients with chronic tic disorders. Methods: Here we report results of the "Fitness to Drive" substudy of the CANNA-TICS trial. The key endpoint was fitness to drive as a binary criterion with a computerized assessment at baseline and after 9 weeks of stable treatment (week 13) with nabiximols or placebo. A patient was considered unfit to drive according to the German Federal Highway Research Institute guidelines. Results: In the substudy, a total of 64 patients (76.6% men, mean±standard deviation of age: 36.8±13.9) were recruited at two study sites. The number of patients who were fit to drive increased from 24 (55.8%) at baseline to 28 (71.8%) at week 13 among 43 patients treated with nabiximols, and decreased from 14 (66.7%) to 10 (52.6%) among 21 patients who received placebo. The risk difference (nabiximols - placebo) was 0.17 (95% confidence interval=-0.08 to 0.43) in favor of nabiximols. Specifically, only 2 of 24 (8.3%) patients in the nabiximols, but 4 of 14 (28.6%) patients in the placebo group changed for the worse from fit (at baseline) to unfit (at week 13) to drive, whereas 8 of 19 (42.1%) patients in the nabiximols, and only 2 of 7 (28.6%) patients in the placebo group improved from unfit to fit. Conclusion: Treatment with nabiximols does not impair skills relevant to driving in those patients with tic disorders who were fit to drive at baseline and even improved fitness to drive in a subset of patients who were unfit to drive before start of treatment. EudraCT number: 2016-000564-42.

Altered dynamic functional and effective connectivity in drug-naive children with Tourette syndrome.

Tourette syndrome (TS) is a developmental neuropsychiatric disorder characterized by repetitive, stereotyped, involuntary tics, the neurological basis of which remains unclear. Although traditional resting-state MRI (rfMRI) studies have identified abnormal static functional connectivity (FC) in patients with TS, dynamic FC (dFC) remains relatively unexplored. The rfMRI data of 54 children with TS and 46 typically developing children (TDC) were analyzed using group independent component analysis to obtain independent components (ICs), and a sliding-window approach to generate dFC matrices. All dFC matrices were clustered into two reoccurring states, the state transition metrics were obtained. We conducted Granger causality and nodal topological analyses to further investigate the brain regions that may play the most important roles in driving whole-brain switching between different states. We found that children with TS spent more time in state 2 (PFDR < 0.001), a state characterized by strong connectivity between ICs, and switched more quickly between states (PFDR = 0.025) than TDC. The default mode network (DMN) may play an important role in abnormal state transitions because the FC that changed the most between the two states was between the DMN and other networks. Additionally, the DMN had increased degree centrality, efficiency and altered causal influence on other networks. Certain alterations related to executive function (r = -0.309, P < 0.05) and tic symptom ratings (r = 0.282; 0.413, P < 0.05) may represent important aspects of the pathophysiology of TS. These findings facilitate our understanding of the neural basis for the clinical presentation of TS.

Relationship between transcranial magnetic stimulation markers of motor control and clinical recovery in obsessive compulsive disorder/Gilles de la Tourette syndrome: a proof of concept case study.

Obsessive compulsive disorder (OCD) and Gilles de la Tourette syndrome (GTS) are neurodevelopmental disorders characterized by difficulties in controlling intrusive thoughts (obsessions) and undesired actions (tics), respectively. Both conditions have been associated with abnormal inhibition but a tangible deficit of inhibitory control abilities is controversial in GTS. Here, we examined a 25 years-old male patient with severe OCD symptoms and a mild form of GTS, where impairments in motor control were central. Transcranial magnetic stimulation (TMS) was applied over the primary motor cortex (M1) to elicit motor-evoked potentials (MEPs) during four experimental sessions, allowing us to assess the excitability of motor intracortical circuitry at rest as well as the degree of MEP suppression during action preparation, a phenomenon thought to regulate movement initiation. When tested for the first time, the patient presented a decent level of MEP suppression during action preparation, but he exhibited a lack of intracortical inhibition at rest, as evidenced by reduced short-interval intracortical inhibition (SICI) and long-interval intracortical inhibition (LICI). Interestingly, the patient's symptomatology drastically improved over the course of the sessions (reduced obsessions and tics), coinciding with feedback given on his good motor control abilities. These changes were reflected in the TMS measurements, with a significant strengthening of intracortical inhibition (SICI and LICI more pronounced than previously) and a more selective tuning of MEPs during action preparation; MEPs became even more suppressed, or selectively facilitated depending on the behavioral condition in which they we probed. This study highlights the importance of better understanding motor inhibitory mechanisms in neurodevelopmental disorders and suggests a biofeedback approach as a potential novel treatment.

Mapping Gilles de la Tourette syndrome through the distress and relief associated with tic-related behaviors: an fMRI study

Personal distress associated with tic urges or inhibition and relief associated with tic production are defining features of the personal experience in Gilles de la Tourette syndrome (GTS). These affective phenomena have not been studied using fMRI, hindering our understanding of GTS pathophysiology and possible treatments. Here, we present a novel cross-sectional fMRI study designed to map tic-related phenomenology using distress and relief as predicting variables. We adopted a mental imagery approach and dissected the brain activity associated with different phases of tic behaviors, premonitory urges, and the ensuing tic execution or inhibition: these were compared with the mental simulation of “relaxed situations” and pre-determined stereotyped motor behaviors. We then explored whether the ensuing brain patterns correlated with the distress or relief perceived for the different phases of the tasks. Patients experienced a higher level of distress during the imagery of tic-triggering scenarios and no relief during tic inhibition. On the other hand, patients experienced significant relief during tic imagery. Distress during tic-triggering scenarios and relief during tic imagery were significantly correlated. The distress perceived during urges correlated with increased activation in cortical sensorimotor areas, suggesting a motor alarm. Conversely, relief during tic execution was positively associated with the activity of a subcortical network. The activity of the putamen was associated with both distress during urges and relief during tic execution. These findings highlight the importance of assessing the affective component of tic-related phenomenology. Subcortical structures may be causally involved in the affective component of tic pathophysiology, with the putamen playing a central role in both tic urge and generation. We believe that our results can be readily translated into clinical practice for the development of personalized treatment plans tailored to each patient’s unique needs.

Micropopulation mapping of the mouse parafascicular nucleus connections reveals diverse input-output motifs.

In primates, including humans, the centromedian/parafascicular (CM-Pf) complex is a key thalamic node of the basal ganglia system. Deep brain stimulation in CM-Pf has been applied for the treatment of motor disorders such as Parkinson's disease or Tourette syndrome. Rodents have become widely used models for the study of the cellular and genetic mechanisms of these and other motor disorders. However, the equivalence between the primate CM-Pf and the nucleus regarded as analogous in rodents (Parafascicular, Pf) remains unclear. Here, we analyzed the neurochemical architecture and carried out a brain-wide mapping of the input-output motifs in the mouse Pf at micropopulation level using anterograde and retrograde labeling methods. Specifically, we mapped and quantified the sources of cortical and subcortical input to different Pf subregions, and mapped and compared the distribution and terminal structure of their axons. We found that projections to Pf arise predominantly (>75%) from the cerebral cortex, with an unusually strong (>45%) Layer 5b component, which is, in part, contralateral. The intermediate layers of the superior colliculus are the main subcortical input source to Pf. On its output side, Pf neuron axons predominantly innervate the striatum. In a sparser fashion, they innervate other basal ganglia nuclei, including the subthalamic nucleus (STN), and the cerebral cortex. Differences are evident between the lateral and medial portions of Pf, both in chemoarchitecture and in connectivity. Lateral Pf axons innervate territories of the striatum, STN and cortex involved in the sensorimotor control of different parts of the contralateral hemibody. In contrast, the mediodorsal portion of Pf innervates oculomotor-limbic territories in the above three structures. Our data thus indicate that the mouse Pf consists of several neurochemically and connectively distinct domains whose global organization bears a marked similarity to that described in the primate CM-Pf complex.

The inflammatory injury of microglia involved in Tourette syndrome development

Tourette Syndrome (TS), a chronic neuroinflammatory disorder, is characterized by motor and vocal tics. Microglial inflammatory activity in TS is increased, while microglial-mediated clearance mechanisms are compromised. Our study aimed to investigate the effect of puerarin on microglial inflammation. Our study confirmed that 20 mg/mL of puerarin was the optimal intervention concentration by CCK8 analysis. Furthermore, we found that puerarin could inhibit proinflammatory factors and up-regulate anti-inflammatory factors at the protein and mRNA levels, thus playing a role in regulating microglial inflammation. This study provides a new strategy for regulating neuroinflammation in TS.

Causal relationships between atopic dermatitis and psychiatric disorders: a bidirectional two-sample Mendelian randomization study

BackgroundObservational studies have suggested the potential associations between atopic dermatitis (AD) and psychiatric disorders. However, the causal relationship between them remains uncertain. This study aimed to evaluate the potential bidirectional causal relationship between AD and psychiatric disorders, including autism spectrum disorder (ASD), major depressive disorder (MDD), attention deficit hyperactivity disorder (ADHD), bipolar disorder (BD), anorexia nervosa (AN), Tourette syndrome (TS), schizophrenia, and anxiety.MethodsBidirectional two-sample Mendelian randomization (MR) was employed to elucidate the causality between AD and psychiatric disorders, using summary statistics from the most comprehensive genome-wide association studies conducted on AD (Ncases = 60,653, Ncontrols = 804,329). Psychiatric disorders were derived from the Psychiatric Genomics Consortium and were independent of AD data sources. The MR analysis entailed the implementation of multiple methods, including the inverse variance weighted method, MR-Egger regression method, weighted median method, simple mode method, and weighted mode method.ResultsBidirectional two-sample MR analysis uncovered significant causal associations between AD and severe psychiatric disorders. Specifically, liability to AD was associated with increased risk of ADHD (OR = 1.116; 95% CI: [1.009, 1.234]; P = 0.033) and ASD (OR = 1.131; 95% CI: [1.023, 1.251]; P = 0.016). Additionally, evidence suggested that liability to ADHD (OR = 1.112; 95% CI: [1.094, 1.130]; P = 9.20e-40), liability to AN (OR = 1.1; 95% CI: [1.068, 1.134]; P = 4.45e-10) and liability to BD (OR = 1.067; 95% CI: [1.009, 1.128]; P = 0.023) were associated with an increased risk of AD. Only the causal association between AD and ASD was independent of the reverse effect bias. These causal associations were robust and not affected by biases of heterogeneity and horizontal pleiotropy.ConclusionsOur study emphasizes the significant causal association between AD and an increased risk of ASD, and also identifying BD and AN as risk factors for AD.

Parent-Report Sleep Disturbances and Everyday Executive Functioning Difficulties in Children with Tourette Syndrome

ABSTRACT There is an increasing need to identify and treat sleep disturbances in Tourette syndrome (TS), a neurodevelopmental condition characterized by tics. This study explored sleep, tics, and executive functioning in children with TS (n=136) and neurotypical controls (n=101) through parent-report scales and open-ended questions. 85% of children with TS scored in the clinical range for a sleep disorder. Higher tic severity predicted increased sleep disturbances and executive difficulties. Qualitative insights indicated a bidirectional link between sleep and tics, which warrants consideration in clinical settings. Further research is needed to explore causal links.

Gender Representation in Academic Publications of Tourette Syndrome Research: An Analysis of Authorship Trends.

Tourette syndrome, characterized by phonic and motor tics, is a neurodevelopmental disorder that significantly affects the quality of life of people with the condition. With over 1500 articles published in the last decade alone, this study aims to analyze the gender trends in publications related to Tourette syndrome from 2013 to 2022, examining the number of female authors as first authors and predicting future changes in female participation. The aim of this study is to analyze the gender trends of the first author in publications related to "Tourette Syndrome" from PubMed-indexed publications from January 2013 to December 2022. A bibliometric analysis was conducted by the search engine PubMed for articles pertaining to "Tourette Syndrome". NamSor app V.2 (Namsor™ Applied Onomastics, NamSor SAS, Versailles, France), an application programming interface (API), was used to identify the gender of the first publishing author. Statistical analysis and graphic models were produced using R software (R Foundation for Statistical Computing, Vienna, Austria), ARIMA (Autoregressive Integrated Moving Average) model, and DataWrapper (Datawrapper GmbH, Berlin Prenzlauer Berg, Germany). Based on the analysis of 1052 publications on Tourette Syndrome, it was found that 54.8% (n=576) of the first authors were females. A significant association was observed between gender ratios and country of publication. Statistical forecasting models suggest that female participation in Tourette research is expected to rise to approximately 60by the year 2027. Therefore, the study highlights the progress made in achieving gender parity in Tourette syndrome research, with female-led publications being on par with male-led publications. However, there is still a need to address the global gender gap and geographical disparities in research to work towards a more inclusive and diverse academic environment.

Exploring protocol development: Implementing systematic contextual memory to enhance real-time fMRI neurofeedback.

The goal of this study was to explore the development and implementation of a protocol for real-time fMRI neurofeedback (rtfMRI-nf) and to assess the potential for enhancing the selective brain activation using stimuli from Virtual Reality (VR). In this study we focused on two specific brain regions, supplementary motor area (SMA) and right inferior frontal gyrus (rIFG). Publications by other study groups have suggested impaired function in these specific brain regions in patients with the diagnoses Attention Deficit Hyperactivity Disorder (ADHD) and Tourette's Syndrome (TS). This study explored the development of a protocol to investigate if attention and contextual memory may be used to systematically strengthen the procedure of rtfMRI-nf. We used open-science software and platforms for rtfMRI-nf and for developing a simulated repetition of the rtfMRI-nf brain training in VR. We conducted seven exploratory tests in which we updated the protocol at each step. During rtfMRI-nf, MRI images are analyzed live while a person is undergoing an MRI scan, and the results are simultaneously shown to the person in the MRI-scanner. By focusing the analysis on specific regions of the brain, this procedure can be used to help the person strengthen conscious control of these regions. The VR simulation of the same experience involved a walk through the hospital toward the MRI scanner where the training sessions were conducted, as well as a subsequent simulated repetition of the MRI training. The VR simulation was a 2D projection of the experience.The seven exploratory tests involved 19 volunteers. Through this exploration, methods for aiming within the brain (e.g. masks/algorithms for coordinate-system control) and calculations for the analyses (e.g. calculations based on connectivity versus activity) were updated by the project team throughout the project. The final procedure involved three initial rounds of rtfMRI-nf for learning brain strategies. Then, the volunteers were provided with VR headsets and given instructions for one week of use. Afterward, a new session with three rounds of rtfMRI-nf was conducted. Through our exploration of the indirect effect parameters - brain region activity (directed oxygenated blood flow), connectivity (degree of correlated activity in different regions), and neurofeedback score - the volunteers tended to increase activity in the reinforced brain regions through our seven tests. Updates of procedures and analyses were always conducted between pilots, and never within. The VR simulated repetition was tested in pilot 7, but the role of the VR contribution in this setting is unclear due to underpowered testing. This proof-of-concept protocol implies how rtfMRI-nf may be used to selectively train two brain regions (SMA and rIFG). The method may likely be adapted to train any given region in the brain, but readers are advised to update and adapt the procedure to experimental needs.

Knockdown of the GABARAP ortholog Atg8a elicits deficits in learning and promotes obsessive behaviors in Drosophila melanogaster.

In humans, trafficking of the GABA(A) receptor by GABARAP can lead to obsessive behaviors and learning deficits often in seen in neurological disorders such as Tourette's Syndrome. We find that in Drosophila melanogaster , Atg8a , the ortholog of the human GABARAP gene, is necessary in the nervous system for learning and suppression of excessive grooming. These results suggest that knocking down Atg8a in neurons of Drosophila produces a phenotype similar to that seen in human patients, potentially allowing for use of an Atg8a knockdown background as a suitable invertebrate model for related neurological conditions.

Understanding copy number variations through their genes: a molecular view on 16p11.2 deletion and duplication syndromes.

Neurodevelopmental disorders (NDDs) include a broad spectrum of pathological conditions that affect >4% of children worldwide, share common features and present a variegated genetic origin. They include clinically defined diseases, such as autism spectrum disorders (ASD), attention-deficit/hyperactivity disorder (ADHD), motor disorders such as Tics and Tourette's syndromes, but also much more heterogeneous conditions like intellectual disability (ID) and epilepsy. Schizophrenia (SCZ) has also recently been proposed to belong to NDDs. Relatively common causes of NDDs are copy number variations (CNVs), characterised by the gain or the loss of a portion of a chromosome. In this review, we focus on deletions and duplications at the 16p11.2 chromosomal region, associated with NDDs, ID, ASD but also epilepsy and SCZ. Some of the core phenotypes presented by human carriers could be recapitulated in animal and cellular models, which also highlighted prominent neurophysiological and signalling alterations underpinning 16p11.2 CNVs-associated phenotypes. In this review, we also provide an overview of the genes within the 16p11.2 locus, including those with partially known or unknown function as well as non-coding RNAs. A particularly interesting interplay was observed between MVP and MAPK3 in modulating some of the pathological phenotypes associated with the 16p11.2 deletion. Elucidating their role in intracellular signalling and their functional links will be a key step to devise novel therapeutic strategies for 16p11.2 CNVs-related syndromes.