Neuropsychological aspects of Tourette syndrome: a review

Factor Structure and Psychometric Properties of the Learning, Executive, and Attention Functioning (LEAF) Scale in Young Adults

The Learning, Executive, and Attention Functioning (LEAF) scale is a resource-friendly means of assessing executive functions (EFs) and related constructs (e.g., academic abilities) in children and adolescents that has been adapted for use with adults. However, no study in any population has investigated the factor structure of all LEAF EF items to determine whether items factor in a manner consistent with the originally proposed scale structure. Therefore, we examined LEAF scale responses of 546 young adults (Mage = 20.05, SD = 2.17). Upon removing academic items following a preliminary factor analysis, we performed principal axis factoring on the remaining 39 EF items. The final model accounted for 61.75% of the total variance in LEAF EF items and suggested that these items assess six moderately correlated EF constructs in young adults. We constructed six updated subscales to help researchers measure these EFs in young adults using the LEAF scale, each of which uniquely and differentially predicted measures of self-reported impulsivity, academic difficulties, and learning-related disorder history. Overall, the LEAF promises to be an accessible means of assessing a range of EF constructs in young adults, particularly when updated subscale structures based on factor analysis are used.

Basal ganglia contributions to social cognition: evidence from movement disorders

Introduction and method: Over the last few decades many studies have demonstrated that various populations with movement disorder exhibit a variety of difficulties with social cognition. This brief review paper summarises the major findings of social cognitive research conducted in various hypo- and hyper-kinetic movement disorders (Parkinson's disease, Huntington's disease and Tourette syndrome), with a focus on findings that may shed new light on the functions of the basal ganglia.Results: Task impairments include more predictable difficulties with embodied processes involving the motor system, such as problems with facial expressions and other non-verbal gestures. The cognitive and emotional changes associated with broader frontostriatal dysfunction may also explain some deficits, particularly difficulties with verbal tasks or perspective taking, with impacts varying according to the type of disorder and disease stage. Most intriguingly, transdiagnostic comparisons reveal patterns implying that the role of the basal ganglia in social cognition may be more important than previously recognised.Conclusions: Movement disorders show remarkable overlap in terms of atypical intention attribution across various tasks, as well as relationships between social cognition and behavioural or motivational symptoms (e.g., apathy; anhedonia; impulsivity). The possible mechanisms underlying these similarities are explored with a view to guiding future research.

Sleep and daytime functioning in children with tourette syndrome: A two-week case-control study with actigraphy and cognitive assessments

There is increasing recognition of the high prevalence of sleep issues in children with Tourette syndrome (TS), a condition characterised by motor and vocal tics. Overnight polysomnography (PSG) has been the primary mode of sleep assessment in the TS literature, despite the extensive use of actigraphy in other neurodevelopmental populations. As a result, there are existing research gaps surrounding day-to-day variability of sleep in TS and links to daytime functioning. This study adopts a naturalistic, intensive longitudinal design to examine sleep in children with TS while considering potential links to tic severity and daytime functioning. Participants were 34 children aged between 8 and 12 years (12 with TS, 22 neurotypical controls). Wrist actigraphs tracked sleep-wake cycles across two weeks and a battery of scales and cognitive assessments measured sleep disturbances and daytime functioning. Mixed models using N = 476 nights of actigraphy data found that relative to controls, children with TS had significantly increased time in bed, increased sleep onset latency, reduced sleep efficiency, lower subjective sleep quality, but comparable actual sleep time. Higher self-report tic severity at bedtime did not predict increased sleep onset latency. In the sleep disturbance scale, 83.33 % of children with TS met the clinical cut-off for a sleep disorder. Parent-report emotional, behavioural, and executive difficulties were greater in the TS group relative to controls, but performance on cognitive tasks was comparable between groups. Together, findings highlight sleep disturbances as an important clinical factor to consider in the management of TS, though further research is required to substantiate findings in larger-scale studies. This study demonstrates the feasibility of assessing sleep via actigraphy in children with TS, supporting more widespread use in the future.

The microstructural change of the brain and its clinical severity association in pediatric Tourette syndrome patients

BACKGROUND

Gilles de la Tourette syndrome (GTS) is a prevalent pediatric neurological disorder. Most studies point to abnormalities in the cortico-striato-thalamocortical (CSTC) circuits. Neuroimaging studies have shown GTS's extensive impact on the entire brain. However, due to participant variability and potential drug and comorbidity impact, the results are inconsistent. To mitigate the potential impact of participant heterogeneity, we excluded individuals with comorbidities or those currently undergoing medication treatments. Based on the hypothesis of abnormality within the CSTC circuit, we investigated microstructural changes in white matter using diffusion spectrum imaging (DSI). This study offers the first examination of microstructural changes in treatment-naïve pediatric patients with pure GTS using diffusion spectrum imaging.

METHODS

This single-center prospective study involved 30 patients and 30 age- and gender-matched healthy volunteers who underwent sagittal T1-weighted MRI and DSI. We analyzed generalized fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity.

RESULTS

No significant differences were observed in mean diffusivity and axial diffusivity values between the two groups. However, the patient group exhibited significantly higher generalized fractional anisotropy values in the right frontostriatal tract of the dorsolateral prefrontal cortex, the right frontostriatal tract of the precentral gyrus, and bilateral thalamic radiation of the dorsolateral prefrontal cortex. Additionally, the generalized fractional anisotropy value of the right frontostriatal tract of the precentral gyrus is inversely correlated with the total tic severity scores at the most severe condition.

CONCLUSION

Treatment-naïve pediatric GTS patients demonstrated increased connectivity within the CSTC circuit as per diffusion spectrum imaging, indicating possible CSTC circuit dysregulation. This finding could also suggest a compensatory change. It thus underscores the necessity of further investigation into the fundamental pathological changes in GTS. Nevertheless, the observed altered connectivity in GTS patients might serve as a potential target for therapeutic intervention.

The shared genetic risk factors between Tourette syndrome and obsessive-compulsive disorder

Tourette syndrome (TS) and obsessive-compulsive disorder (OCD) are two neuropsychiatric disorders that frequently co-occur. Previous evidence suggests a shared genetic diathesis underlying the comorbidity of TS and OCD. This review aims to comprehensively summarize the current literature on the genetic factors linked with TS and its comorbidities, with a focus on OCD. Family studies, linkage analysis, cytogenetic studies, and genome-wide association studies (GWAS) have played a pivotal role in identifying common and rare genetic variants connected with TS and OCD. Although the genetic framework of TS and OCD is complex and multifactorial, several susceptibility loci and candidate genes have been identified that might play a crucial role in the pathogenesis of both disorders. Additionally, post-infectious environmental elements have also been proposed to contribute to the development of TS-OCD, although the dynamics between genetic and environmental factors is not yet fully understood. International collaborations and studies with well-defined phenotypes will be crucial in the future to further elucidate the genetic basis of TS and OCD and to develop targeted therapeutic strategies for individuals suffering from these debilitating conditions.

Group comprehensive behavioral intervention for tics contribution to broader cognitive and emotion regulation in children

There is increasing evidence for the effectiveness of behavioral techniques in managing tics in youth with Tourette syndrome and tics disorders (TDs). One such intervention is Comprehensive Behavioral Intervention for Tics (CBIT), which focuses on reducing tic severity by training control and regulation. In view of the regulation deficits characteristic to TDs, in the current study, we aimed to explore the contribution of CBIT beyond tic control, to a wider expression of regulation abilities-cognitive inhibition and emotion regulation. A total of 55 participants with TDs, aged 8-15, who were randomly assigned to group-CBIT or group-Educational Intervention for Tics, were compared on cognitive inhibition tests and use of emotion-regulation strategies, pre- and post-intervention. Whereas on none of the scales a significant interaction effect was found reflecting superiority of CBIT over EIT, repeated measures ANOVA revealed a significant time effect, with post hoc analyses indicating that cognitive inhibition and cognitive reappraisal significantly increased following CBIT intervention only. Within the group-CBIT, the increase in cognitive reappraisal was associated with higher intellectual ability. These findings may lead to a broader understanding of CBIT contribution to more than tic control, but rather to better cognitive and emotional regulation abilities.

Capturing Subtle Neurocognitive Differences in Children with and without Tourette Syndrome through a Fine-Grained Analysis of Design Fluency Profiles

BACKGROUND

Tourette syndrome (TS) can be accompanied by neurocognitive impairment. Only a few studies have focused on executive function assessment in TS using design fluency, providing preliminary results. This study aimed to characterize the detailed design fluency profile of children with TS compared with neurotypical children, while addressing the central concern of frequent comorbidities in studies on TS by considering tic severity and attention-deficit/hyperactivity disorder (ADHD) symptoms and diagnosis.

METHODS

Sixty-one children aged between 6 and 15 years participated and were divided into a TS group (n = 28 (with ADHD n = 15)) and a control group (n = 33). Our objective was addressed by examining a wide range of measures of the Five-Point-Test, presumably sensitive to frontostriatal dysfunction. The total number of designs, repetitions, repetition ratio, unique designs, and numerical, spatial, and total strategies were examined for the total duration of the test (global measures) and at five equal time intervals (process measures).

RESULTS

The TS group produced significantly fewer numerical strategies. Groups did not differ in other global or process measures. ADHD did not affect performance.

CONCLUSIONS

Children with TS do not inherently show general executive dysfunction but may present with subtle neurocognitive characteristics here revealed by comprehensive design fluency profiles.

Electrophysiological signatures of inhibitory control in children with Tourette syndrome and attention-deficit/hyperactivity disorder

Tourette syndrome (TS) and attention-deficit/hyperactivity disorder (ADHD) frequently co-occur, especially in children. Reduced inhibitory control abilities have been suggested as a shared phenotype across both conditions but its neural underpinnings remain unclear. Here, we tested the behavioral and electrophysiological correlates of inhibitory control in children with TS, ADHD, TS+ADHD, and typically developing controls (TDC). One hundred and thirty-eight children, aged 7-14 years, performed a Go/NoGo task during dense-array EEG recording. The sample included four groups: children with TS only (n = 47), TS+ADHD (n = 32), ADHD only (n = 22), and matched TDC (n = 35). Brain activity was assessed with the means of frontal midline theta oscillations, as well as the N200 and P300 components of the event-related potentials. Our analyses revealed that both groups with TS did not differ from other groups in terms of behavioral performance, frontal midline theta oscillations, and event-related potentials. Children with ADHD-only had worse Go/NoGo task performance, decreased NoGo frontal midline theta power, and delayed N200 and P300 latencies, compared to typically developing controls. In the current study, we found that children with TS or TS+ADHD do not show differences in EEG during a Go/NoGo task compared to typically developing children. Our findings however suggest that children with ADHD-only have a distinct electrophysiological profile during the Go/NoGo task as indexed by reduced frontal midline theta power and delayed N200 and P300 latencies.

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.

Neuropsychiatric Aspects of Impulse Control Disorders

Impulse control disorders (ICDs) are neuropsychiatric conditions characterized by the repeated inability to resist an impulse, drive, or temptation to perform an act that is harmful to the person or others. Although classification approaches to ICDs vary both diachronically and synchronically, this group of conditions encompasses a wide range of syndromes, including pathologic gambling, kleptomania, trichotillomania, excoriation (skin picking) disorder, intermittent explosive disorder, pyromania, oppositional defiant, conduct, and antisocial personality disorders. ICDs can play a significant role as comorbidities in both neurodevelopmental (eg, attention-deficit/hyperactivity disorder, Tourette syndrome) and neurodegenerative (eg, Parkinson disease) disorders.

Executive function in children with Tourette syndrome and attention-deficit/hyperactivity disorder: Cross-disorder or unique impairments?

Findings of executive functioning deficits in Tourette syndrome (TS) have so far been inconsistent, possibly due to methodological challenges of previous studies, such as the use of small sample sizes and not accounting for comorbid attention-deficit/hyperactivity disorder (ADHD), obsessive-compulsive disorder (OCD), or medication use. We aimed to address these issues by examining several areas of executive functioning (response inhibition, attentional flexibility, cognitive control, and working memory) and psychomotor speed in 174 8-to-12-year-old children with TS [n = 34 without (TS-ADHD) and n = 26 with comorbid ADHD (TS+ADHD)], ADHD without tics (ADHD-TS; n = 54), and healthy controls (n = 60). We compared executive functioning measures and psychomotor speed between these groups and related these to ADHD severity across the whole sample, and tic severity across the TS groups. Children with TS+ADHD, but not TS-ADHD, made more errors on the cognitive control task than healthy children, while TS-ADHD had a slower psychomotor speed compared to healthy controls. The ADHD group showed impairment in cognitive control and working memory versus healthy controls. Moreover, higher ADHD severity was associated with poorer cognitive control and working memory across all groups; there was no relation between any of the executive functioning measures and tic severity. OCD severity or medication use did not influence our results. In conclusion, we found little evidence for executive function impairments inherent to TS. Executive function problems appear to manifest predominantly in relation to ADHD symptomatology, with both cross-disorder and unique features of neuropsychological functioning when cross-comparing TS and ADHD.

Frequency-Specific Regional Homogeneity Alterations in Tourette Syndrome

Tourette syndrome (TS) is a developmental neuropsychiatric disorder with onset during childhood. Because of its complex spectrum of phenotypes, the underlying pathophysiology of TS is still unclear. Resting-state functional magnetic resonance imaging demonstrated aberrant spontaneous neural synchronization in conventional frequency band (0.01-0.08 Hz) in TS. No published studies have reported abnormalities of local synchronization across different frequency bands. We estimated the alterations of local synchronization across five bands ranging from 0 to 0.25 Hz. Seventy-nine children with TS and 63 age-, sex-, and handedness-matched healthy children were recruited. Frequency-specific regional homogeneity (ReHo) and independent component analysis were used to identify functional alterations between TS and healthy children. TS patients showed significantly increased ReHo in the left precentral gyrus and decreased ReHo in the right operculum. Abnormal ReHo alterations of the superior frontal gyrus, superior parietal gyrus, anterior cingulate gyrus, putamen, superior temporal gyrus, and operculum were observed in different frequency bands. TS patients showed increased connectivity of the right superior frontal gyrus within the left executive control network. In addition, a significantly negative correlation was found between Yale Global Tic Severity Scale (YGTSS) vocal score and ReHo values of the right operculum in the highest frequency bands (0.198-0.25 Hz), while a significant positive correlation was found between YGTSS motor score and altered connectivity of the right superior frontal gyrus. The present study revealed frequency-specific abnormal alterations of ReHo in the whole brain and altered connectivity within the executive control network of TS children. Its neural importance and clinical practicability require further investigation.

Neurophysiological correlate of emotional regulation in cognitive and motor deficits in Tourette's syndrome

Objectives: The present study investigated the role of different emotions in the expression of cognitive and motor control abilities of children having Tourette's syndrome (TS) compared to healthy controls.Methods: The electroencephalography activity of 33 children (mean age in final sample: TS (n = 10) = 10.5 ± 2.3; control (n = 10) = 10.1 ± 2.9) was recorded during a visual task consisting of four emotional face cues (anger, happiness, neutral and sadness) followed by a target in congruent or incongruent position with emotional cue. The participants were asked to indicate the target location.Results: The TS patients showed a shorter latency of the P1 and N170 only for anger cues compared to controls. In addition, sLORETA results showed an increased activation in the left occipital area and a decreased activation in the left amygdala, temporal and cingulate for anger cues in TS patients. Coherently, TS patients showed a lower accuracy of response only with anger cue and severity of tics resulted correlated with the event-related potentials data and behavioural responses linked to anger cue.Conclusions: These results suggest that children with TS process emotions (in particular the anger) differently from the controls, and that its regulation seems to have an important role in the cognitive and motor deficits in TS.

Social communication deficits and restricted repetitive behavior symptoms in Tourette syndrome

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

Psychosocial Profile in Portuguese Adolescents with Chronic Disease Attending an Outpatient Department in a Hospital Setting

Living with a chronic disease (CD) in adolescence involves new multifaceted challenges. This study aims to conduct a psychosocial characterization of a group of adolescents with chronic diseases in a hospital setting and to compare such dimensions for the total group and for different diseases. A cross-sectional study included 135 adolescents with chronic diseases (51.9% boys; 48.1% girls), having an average age of 14±1.5 years (SD=1.5) and attending a paediatric outpatient department in a hospital setting. Statistically significant differences were found among the different chronic diseases for the variables self-regulation (adolescents with diabetes had significantly higher competencies) and multiple psychosomatic symptoms (adolescents with neurologic diseases reported significantly more complaints). Boys presented both better health-related quality of life and psychosomatic health when compared to girls. No statistically significant differences were observed for health-related quality of life, psychosomatic health, resilience, and social support. These findings bring important suggestions especially while planning interventions, which must take into account the promotion of a healthy psychosocial development, through an inclusive perspective (covering different chronic diseases), that take into consideration specific and gendered approaches. Such suggestions might help healthcare professionals to better plan interventions in order to increase their effectiveness.

Tourette syndrome research highlights from 2017

This is the fourth yearly article in the Tourette Syndrome Research Highlights series, summarizing research from 2017 relevant to Tourette syndrome and other tic disorders. The authors briefly summarize reports they consider most important or interesting. The  highlights from 2018 article is being drafted on the Authorea online authoring platform, and readers are encouraged to add references or give feedback on our selections using the comments feature on that page. After the calendar year ends, the article is submitted as the annual update for the Tics collection on F1000Research.

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

BACKGROUND

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

AIMS

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

METHODS

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

RESULTS

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

CONCLUSION

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

Functional Alignment with Anatomical Networks is Associated with Cognitive Flexibility

Cognitive flexibility describes the human ability to switch between modes of mental function to achieve goals. Mental switching is accompanied by transient changes in brain activity, which must occur atop an anatomical architecture that bridges disparate cortical and subcortical regions by underlying white matter tracts. However, an integrated perspective regarding how white matter networks might constrain brain dynamics during cognitive processes requiring flexibility has remained elusive. To address this challenge, we applied emerging tools from graph signal processing to examine whether BOLD signals measured at each point in time correspond to complex underlying anatomical networks in 28 individuals performing a perceptual task that probed cognitive flexibility. We found that the alignment between functional signals and the architecture of the underlying white matter network was associated with greater cognitive flexibility across subjects. By computing a concise measure using multi-modal neuroimaging data, we uncovered an integrated structure-function correlate of human behavior.

A Review of the Neuropsychological Dimensions of Tourette Syndrome

Neurocognitive functioning in Tourette syndrome (TS) has been the subject of intensive research in the past 30 years. A variety of impairments, presumably related to frontal and frontostriatal dysfunctions, have been observed. These impairments were found in various domains, such as attention, memory, executive functions, language, motor and visuomotor functions, among others. In line with contemporary research, other neurocognitive domains have recently been explored in TS, bringing evidence of altered social reasoning, for instance. Therefore, the aims of this review are to give an overview of the neuropsychological dimensions of TS, to report how neuropsychological functions evolve from childhood to adulthood, and to explain how various confounding factors can affect TS patients' performance in neuropsychological tasks. Finally, an important contribution of this review is to show how recent research has confirmed or changed our beliefs about neuropsychological functioning in TS.

Cognitive flexibility and its electrophysiological correlates in Gilles de la Tourette syndrome

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Gilles de la Tourette syndrome (GTS) may involve cognitive inflexibility.

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A meta-analysis reveals GTS-related deficits on the Wisconsin Card Sorting Test.

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Card-sorting deficits are larger in children than in adults with GTS.

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Adults with GTS show electrophysiological signs of enhanced cognitive control.

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This change may underlie the normalization of cognitive flexibility in adult GTS.

Motor symptoms in Gilles de la Tourette syndrome (GTS) have been related to changes in frontostriatal brain networks. These changes may also give rise to alterations in cognitive flexibility. However, conclusive evidence for altered cognitive flexibility in patients with GTS is still lacking. Here, we meta-analyzed data from 20 neuropsychological studies that investigated cognitive flexibility in GTS using the Wisconsin Card Sorting Test (WCST). Results revealed medium-sized GTS-related performance deficits, which were significantly modulated by age: Whilst being substantial in children and adolescents with GTS, WCST deficits seem to dissolve in adult patients with GTS. This age-related normalization of WCST performance might result from the compensatory recruitment of cognitive control in adult patients with GTS. We addressed this possibility by examining neural correlates of proactive and reactive cognitive control in an event-related potential (ERP) study. We analyzed cue- and target-locked ERPs from 23 adult patients with GTS and 26 matched controls who completed a computerized version of the WCST. Compared to controls, patients with GTS showed a marked increase in parietal cue-locked P3 activity, indicating enhanced proactive cognitive control. We conclude that the additional recruitment of proactive cognitive control might ensure flexible cognitive functioning in adult patients with GTS.

Set-Shifting Deficits: A Possible Neurocognitive Endophenotype for Tourette Syndrome Without ADHD

OBJECTIVE

Tourette syndrome (TS) can be associated with cognitive dysfunction. We assessed a range of cognitive abilities in adults with TS without comorbid disorders.

METHOD

Participants completed tests of sustained attention, verbal and non-verbal reasoning, comprehension, verbal fluency, working memory, inhibition, and set-shifting. We compared patients' task performance with that of healthy controls, and evaluated relationships between cognitive abilities and symptoms of obsessive-compulsive disorder (OCD), ADHD, impulse control problems, and mood disorders.

RESULTS

Patients with TS exhibited impairments on four measures assessing response inhibition, fine motor control, set-shifting, and sustained attention. The Wisconsin Card Sorting Test (WCST) discriminated best between patients and controls. Patients' deficits were not correlated with tic severity or symptoms related to OCD, ADHD, or mood disorders.

CONCLUSION

Deficits on the WCST could constitute a neurocognitive endophenotype for TS, reflecting dysfunction within neural networks involving basal ganglia, pre-supplementary motor area, and inferior prefrontal regions.

P300 Source Localization Contrasts in Body-Focused Repetitive Behaviors and Tic Disorders

Tic disorders (TD) and body-focused repetitive behaviors (BFRB) have similar phenotypes that can be challenging to distinguish in clinical settings. Both disorders show high rates of comorbid psychiatric conditions, dysfunctional basal ganglia activity, atypical cortical functioning in the prefrontal and motor cortical regions, and cognitive deficits. Clinicians frequently confound the two disorders and it is important to find reliable objective methods to discriminate TD and BFRB. Neuropsychological tests and event-related potential (ERP) studies have yielded inconsistent results regarding a possible context updating deficit in TD and BFRB patients. However, most previous studies did not control for the presence of comorbid psychiatric condition and medication status, which might have confounded the findings reported to date. Hence, we aimed to investigate the psychophysiology of working memory using ERP in carefully screened TD and BFRB patients excluding those with psychiatric comorbidity and those taking psychoactive medication. The current study compared 12 TD patients, 12 BRFB patients, and 15 healthy control participants using a motor oddball task (button press). The P300 component was analyzed as an index of working memory functioning. Results showed that BFRB patients had decreased P300 oddball effect amplitudes over the right hemisphere compared to the TD and control groups. Clinical groups presented different scalp distributions compared to controls, which could represent a potential endophenotype candidate of BFRB and TD.

The puzzling question of inhibitory control in Tourette syndrome: A meta-analysis

Tourette syndrome (TS) is a neuropsychiatric disorder involving motor and phonic tics. Inhibitory control is a key issue in TS, and many disruptive or impulsive behaviors might arise from inhibitory deficits. However, conflicting findings regarding TS patients' inhibitory performance in neuropsychological tasks have been reported throughout the literature. Therefore, this meta-analysis aimed to evaluate inhibitory control through neuropsychological tasks, and to analyze the factors modulating inhibitory deficits. To this end, a literature search was performed through MEDLINE and PsycINFO, to retrieve studies including neuropsychological tasks that assessed inhibitory control in TS patients. Of the 4020 studies identified, 61 were included in the meta-analysis, for a total of 1717 TS patients. Our analyses revealed a small to medium effect in favor of inhibitory deficits in TS patients. This effect was larger in TS+ADHD patients, but pure TS patients also showed some inhibitory deficits. Therefore, deficits in inhibitory control seem to be an inherent component of TS, and are exacerbated when ADHD is concomitant.

Dysfunctions of the basal ganglia-cerebellar-thalamo-cortical system produce motor tics in Tourette syndrome

Motor tics are a cardinal feature of Tourette syndrome and are traditionally associated with an excess of striatal dopamine in the basal ganglia. Recent evidence increasingly supports a more articulated view where cerebellum and cortex, working closely in concert with basal ganglia, are also involved in tic production. Building on such evidence, this article proposes a computational model of the basal ganglia-cerebellar-thalamo-cortical system to study how motor tics are generated in Tourette syndrome. In particular, the model: (i) reproduces the main results of recent experiments about the involvement of the basal ganglia-cerebellar-thalamo-cortical system in tic generation; (ii) suggests an explanation of the system-level mechanisms underlying motor tic production: in this respect, the model predicts that the interplay between dopaminergic signal and cortical activity contributes to triggering the tic event and that the recently discovered basal ganglia-cerebellar anatomical pathway may support the involvement of the cerebellum in tic production; (iii) furnishes predictions on the amount of tics generated when striatal dopamine increases and when the cortex is externally stimulated. These predictions could be important in identifying new brain target areas for future therapies. Finally, the model represents the first computational attempt to study the role of the recently discovered basal ganglia-cerebellar anatomical links. Studying this non-cortex-mediated basal ganglia-cerebellar interaction could radically change our perspective about how these areas interact with each other and with the cortex. Overall, the model also shows the utility of casting Tourette syndrome within a system-level perspective rather than viewing it as related to the dysfunction of a single brain area.

Tourette syndrome is a neuropsychiatric disorder characterized by vocal and motor tics. Tics represent a cardinal symptom traditionally associated with a dysfunction of the basal ganglia leading to an excess of the dopamine neurotransmitter. This view gives a restricted clinical picture and limits therapeutic approaches because it ignores the influence of altered interactions between the basal ganglia and other brain areas. In this respect, recent evidence supports a more articulated framework where cerebellum and cortex are also involved in tic production. Building on these data, we propose a computational model of the basal ganglia-cerebellar-thalamo-cortical network to investigate the specific mechanisms underlying motor tic production. The model reproduces the results of recent experiments and suggests an explanation of the system-level processes underlying tic production. Moreover, it furnishes predictions related to the amount of tics generated when there are dysfunctions in the basal ganglia-cerebellar-thalamo-cortical circuits. These predictions could be important in identifying new brain target areas for future therapies based on a system-level view of Tourette syndrome.

Dissociable Response Inhibition in Children With Tourette's Syndrome Compared With Children With ADHD

OBJECTIVE

This study investigates whether performance in a verbal response task (Color-Word Interference Test [CWIT]) and a motor response task (Conners' Continuous Performance Test [CCPT]) discriminates children with Tourette's Syndrome (TS), ADHD, and typically developing children (TDC).

METHOD

Nineteen children with TS, 79 with ADHD, and 50 with TDC participated (8-17 years).

RESULTS

Children with TS committed significantly fewer errors in the verbal response task than those with ADHD. Moreover, children with TS but without ADHD performed better than TDC. Errors in motor task and speed of response did not distinguish between groups. A cautious tendency of response correlated positively with rates of tics in children with TS.

CONCLUSION

Children with TS were superior in inhibiting a prepotent verbal response; however, comorbidity with ADHD in those children negatively influenced performance. Results support the hypothesis that levels of inhibitory control distinguish children with TS, ADHD, and TDC.

Impact of co-morbid attention-deficit and hyperactivity disorder on cognitive function in male children with Tourette syndrome: A controlled study

Tourette syndrome (TS) and attention-deficit and hyperactivity disorder (ADHD) are co-morbid neurodevelopmental conditions affecting more commonly male patients. We set out to determine the impact of co-morbid ADHD on cognitive function in male children with TS by conducting a controlled study. Participants included four matched groups of unmedicated children (age range 6-15 years): TS (n=13), TS+ADHD (n=8), ADHD (n=39), healthy controls (n=66). Following clinical assessment, each participant completed a battery of tests from the Wechsler Intelligence Scale for Children-III, the Italian Battery for ADHD, the Tower of London test, the Corsi test, and the Digit Span test. All patient groups reported significantly lower scores than healthy controls across the neuropsychological tests involving executive functions. The TS+ADHD group was the most severely affected, followed by the ADHD group and the TS group, particularly in the tests assessing planning ability, inhibitory function, working memory and visual attention, but not auditory attention. Problems in executive functions are more common in patients with neurodevelopmental disorders than controls. Deficits in planning ability, inhibitory function, working memory and visual attention reported by children with TS appear to be more strongly related to the presence of co-morbid ADHD symptoms than core TS symptoms.

Single Case Study: Neuropsychological Functioning in a Patient Diagnosed with Intermittent Explosive Disorder Pre and Post Neurosurgery

Intermittent explosive disorder (IED) is characterized by a difficulty to resist the urge to carry out a recognized harmful behavior. The central symptom is aggressiveness, expressed in isolated episodes. Executive function impairments are habitually found in impulse control disorders. Neuropsychology of impulsivity is related to dysfunctions in the orbito-frontal cortex, dorsolateral cortex and anterior-cingulated regions, being consequently involved in cognitive mechanisms of inhibition. Lesions in those areas are common in IED. In the most severe cases of IED, surgical procedures are required for treatment. In this study, we examined JML; a patient suffering from a severe case of IED. He experienced frequent episodes of auto and heteroaggression and multiple psychiatric admissions, and thus stereotactic surgery was the recommended treatment. The procedure consisted of an electrode situated lateral to the lateral ventricle, targeting the projections between frontal and subcortical affected regions. We aimed to study the neuropsychological functioning of JML, before and after electrode implantation. Our results suggested that surgery in IED improves cognitive performance at some levels. JML significantly improved his cognitive flexibility, measured with WCST, and alternate attention assessed with CPT and TMT-B tests, after electrode implantation. Cognitive flexibility deficits may be also related to increased aggressiveness. Therefore, improvements at this level may involve a reduction of impulsivity and aggressive behavior.

Response Inhibition in Tic Disorders: Waiting to Respond Is Harder When ADHD Is Present

OBJECTIVE

Tic disorders such as Gilles-de-la-Tourette syndrome (TS) are associated with difficulties in withholding movements and sometimes inappropriate actions. The present study examined whether these disorders lead to a specific difficulty in withholding preprogrammed voluntary movements irrespective of decisions on whether or not to move.

METHOD

Children with TS with or without attention-deficit hyperactivity disorder (ADHD) and controls performed a fast-paced simple reaction time task involving responses to a target in a rapid letter stream (9 letters/s, average foreperiod 332 ms) with feedback on response speed.

RESULTS

The ADHD group showed more premature responses and more variable response time than other groups, whether the timing of the target was predictable or not.

CONCLUSION

The data indicate that in tic disorders, the presence of ADHD is associated with difficulties in waiting to initiate preprogrammed movements independently of response selection or response timing difficulties.

Cognitive Flexibility and Social Responsiveness in Children and Adolescents with Tourette Syndrome

This study examined cognitive flexibility and social responsiveness in children and adolescents with Tourette Syndrome (TS). Thirty one subjects with TS were compared to 32 age-matched healthy controls. Assessments included semi-structured interviews to assess psychopathology, parent-rated Social Responsiveness Scale (SRS) and a brief neuropsychological battery selected as measures of cognitive flexibility. Completion time for both Trail Making Tests (TMT-A and TMT-B) were significantly longer for TS group than controls, however the difference in perseverative errors on Wisconsin Card Sorting Test (WCST) was not significant. SRS total score was significantly higher in the TS group compared to controls, indicating greater impairment in social responsiveness. Group difference for TMTs and SRS failed to reach significance after controlling for co-occurring conditions. Clinicians might consider social impairment in the evaluation plan of children and adolescents with Tourette syndrome.

Neuropsychological investigations in obsessive-compulsive disorder: A systematic review of methodological challenges

The inconsistent nature of the neuropsychology literature pertaining to obsessive-compulsive disorder (OCD) has long been recognized. However, individual studies, systematic reviews, and recent meta-analytic reviews were unsuccessful in establishing a consensus regarding a disorder-specific neuropsychological profile. In an attempt to identify methodological factors that may contribute to the inconsistency that is characteristic of this body of research, a systematic review of methodological factors in studies comparing OCD patients and non-psychiatric controls on neuropsychological tests was conducted. This review covered 115 studies that included nearly 3500 patients. Results revealed a range of methodological weaknesses. Some of these weaknesses have been previously noted in the broader neuropsychological literature, while some are more specific to psychiatric disorders, and to OCD. These methodological shortcomings have the potential to hinder the identification of a specific neuropsychological profile associated with OCD as well as to obscure the association between neurocognitive dysfunctions and contemporary neurobiological models. Rectifying these weaknesses may facilitate replicability, and promote our ability to extract cogent, meaningful, and more unified inferences regarding the neuropsychology of OCD. To that end, we present a set of methodological recommendations to facilitate future neuropsychology research in psychiatric disorders in general, and in OCD in particular.

Are Motor Skills and Motor Inhibitions Impaired in Tourette Syndrome? A Review

Tourette syndrome (TS) is a neurodevelopmental motor disorder described as an inability to inhibit unwanted motor movements. This article reviews research on the execution and inhibition of voluntary motor movements in TS. Over last two decades, a number of studies have addressed the structural and functional deficits associated with this syndrome. Only a limited number of studies have assessed the motor skills in these patients but have failed to reach any conclusive outcome. In the domain of response inhibition also, studies have reported arguable impairments in these patients. It is suggested that these conflicting results can be attributed to co-occurring comorbid conditions, the constraints posed by variable age groups, lack of control measures, and lack of specificity of domains addressed. This review will describe a way in which future research can be directed to increase our knowledge of this otherwise complex spectrum of disorders.

Cognitive-behavioral therapy induces sensorimotor and specific electrocortical changes in chronic tic and Tourette's disorder

BACKGROUND

Tic disorders, such as the Gilles de la Tourette syndrome and persistent tic disorder, are neurodevelopmental movement disorders involving impaired motor control. Hence, patients show repetitive unwanted muscular contractions in one or more parts of the body. A cognitive-behavioral therapy, with a particular emphasis on the psychophysiology of tic expression and sensorimotor activation, can reduce the frequency and intensity of tics. However, its impact on motor activation and inhibition is not fully understood.

METHODS

To study the effects of a cognitive-behavioral therapy on electrocortical activation, we recorded the event-related potentials (ERP) and lateralized readiness potentials (LRP), before and after treatment, of 20 patients with tic disorders and 20 healthy control participants (matched on age, sex and intelligence), during a stimulus-response compatibility inhibition task. The cognitive-behavioral therapy included informational, awareness training, relaxation, muscle discrimination, cognitive restructuration and relapse prevention strategies.

RESULTS

Our results revealed that prior to treatment; tic patients had delayed stimulus-locked LRP onset latency, larger response-locked LRP peak amplitude, and a frontal overactivation during stimulus inhibition processing. Both stimulus-locked LRP onset latency and response-locked LRP peak amplitude normalized after the cognitive behavioral therapy completion. However, the frontal overactivation related to inhibition remained unchanged following therapy.

CONCLUSIONS

Our results showed that P300 and reaction times are sensitive to stimulus-response compatibility, but are not related to tic symptoms. Secondly, overactivity of the frontal LPC and impulsivity in TD patients were not affected by treatment. Finally, CBT had normalizing effects on the activation of the pre-motor and motor cortex in TD patients. These results imply specific modifications of motor processes following therapy, while inhibition processes remained unchanged. Given that LRPs are partially generated within the sensorimotor and supplementary motor area, the reported reduction in tic frequency and improvements of LRPs components suggest that CBT induced a physiological change in patients' motor area.

Timing recalibration in childhood Tourette syndrome associated with persistent pimozide treatment

In this study, we have tested the effects of the dopamine D2 receptor blocker pimozide on timing performance in patients with Tourette syndrome (TS). Nine children with TS were tested off-medication and following 3 months of daily treatment with pimozide. Subjects completed a time reproduction and a time production task using supra-second temporal intervals. We show that pimozide improves motor timing performance by reducing the patients' variability in reproducing the duration of visual stimuli. On the other hand, this medication has no effect on the reproduction accuracy and on both variability and accuracy of the performance on the time production task. Our results suggest that pimozide might have improved motor timing variability as a result of its beneficial side effect on endogenous dopamine levels (i.e., normalization).

Oculomotor executive function abnormalities with increased tic severity in Tourette syndrome

BACKGROUND

Reports conflict as to whether Tourette syndrome (TS) confers deficits in executive function. This study's aim was to evaluate executive function in youths with TS using oculomotor tasks while controlling for confounds of tic severity, age, medication, and severity of comorbid disorders.

METHOD

Four saccade tasks requiring the executive functions of response generation, response inhibition, and working memory (prosaccade, antisaccade, 0-back, and 1-back) were administered. Twenty youths with TS and low tic severity (TS-low), nineteen with TS and moderate tic severity (TS-moderate), and 29 typically developing control subjects (Controls) completed the oculomotor tasks.

RESULTS

There were small differences across groups in the prosaccade task. Controlling for any small sensorimotor differences, TS-moderate subjects had significantly higher error rates than Controls and TS-low subjects in the 0-back and 1-back tasks. In the 1-back task, these patients also took longer to respond than Controls or TS-low subjects.

CONCLUSIONS

In a highly controlled design, the findings demonstrate for the first time that increased tic severity in TS is associated with impaired response inhibition and impaired working memory and that these executive function deficits cannot be accounted for by differences in age, medication or comorbid symptom severity.

Neurofeedback and its possible relevance for the treatment of Tourette syndrome

Neurofeedback is an increasingly recognized therapeutic option in various neuropsychiatric disorders to treat dysfunctions in cognitive control as well as disorder-specific symptoms. In this review we propose that neurofeedback may also reflect a valuable therapeutic option to treat executive control functions in Gilles-de-la-Tourette syndrome (GTS). Deficits in executive control functions when ADHD symptoms appear in GTS likely reflect pathophysiological processes in cortico-thalamic-striatal circuits and may also underlie the motor symptoms in GTS. Such executive control deficits evident in comorbid GTS/ADHD depend on neurophysiological processes well-known to be modifiable by neurofeedback. However, so far efforts to use neurofeedback to treat cognitive dysfunctions are scarce. We outline why neurofeedback should be considered a promising treatment option, what forms of neurofeedback may prove to be most effective and how neurofeedback may be implemented in existing intervention strategies to treat comorbid GTS/ADHD and associated dysfunctions in cognitive control. As cognitive control deficits in GTS mostly appear in comorbid GTS/ADHD, neurofeedback may be most useful in this frequent combination of disorders.

The relation between attention and tic generation in Tourette syndrome

Objective: Many neuropsychiatric disorders involve abnormal attentional processing. Systematic investigations of how attention may affect tic frequency in Tourette syndrome are lacking. Method: Patients performed rhythmic finger movements, approximately once every 2 s. Each movement triggered a unique visual color stimulus. Patients were asked to monitor and remember their finger actions, the external colors caused by their actions, or their tics. Sixteen adult Tourette syndrome patients performed each task twice: once while inhibiting tics, and once without inhibiting tics. Results: During the “freely tic” condition, patients had significantly fewer tics when attending to finger movements, or to the ensuing colors, compared with when attending to their tics. Attention to fingers produced the fewest tics overall. During tic suppression, tic frequency was reduced to an equal level in all conditions. Conclusions: Focusing attention away from tics significantly reduces tic frequency. This attentional process may operate by regulating motor noise.

Counterfactual thinking in Tourette's syndrome: a study using three measures

Pathophysiological evidence suggests an involvement of frontostriatal circuits in Tourette syndrome (TS) and cognitive abnormalities have been detected in tasks sensitive to cognitive deficits associated with prefrontal damage (verbal fluency, planning, attention shifting, working memory, cognitive flexibility, and social reasoning). A disorder in counterfactual thinking (CFT), a behavioural executive process linked to the prefrontal cortex functioning, has not been investigated in TS. CFT refers to the generation of a mental simulation of alternatives to past factual events, actions, and outcomes. It is a pervasive cognitive feature in everyday life and it is closely related to decision-making, planning, problem-solving, and experience-driven learning—cognitive processes that involve wide neuronal networks in which prefrontal lobes play a fundamental role. Clinical observations in patients with focal prefrontal lobe damage or with neurological and psychiatric diseases related to frontal lobe dysfunction (e.g., Parkinson's disease, Huntington's disease, and schizophrenia) show counterfactual thinking impairments. In this work, we evaluate the performance of CFT in a group of patients with Tourette's syndrome compared with a group of healthy participants. Overall results showed no statistical differences in counterfactual thinking between TS patients and controls in the three counterfactual measures proposed. The possible explanations of this unexpected result are discussed below.

Dimensions and disorder specificity of impulsivity in pathological gambling

Impulsivity is a core characteristic of pathological gambling (PG), even though the underlying structure and disorder specificity is unclear. This study aimed to explore different dimensions of impulsivity in a clinical sample including PG. Furthermore, we aimed to test which alterations of the impulsivity-related dimensions are disorder specific for PG. Participants were individuals diagnosed with PG (n=51) and two groups also characterized by various impulsive behaviors: an alcohol dependence (AD; n=45) and a Gilles de la Tourette syndrome (GTS; n=49) group. A healthy control (HC; n=53) group was recruited as comparison group. A comprehensive assessment was used including impulsivity-related and antipodal parameters of the Stop Signal Task, Stroop Task, Tower of London Task, Card Playing Task, Iowa Gambling Task and the Barratt Impulsiveness Scale-11. Principal axis factor analysis revealed four impulsivity-related dimensions that were labeled 'self-reported impulsivity', 'prepotent response impulsivity', 'choice impulsivity' and 'motor impulsivity'. The PG group scored significantly higher on all four dimensions compared to the HC group. In contrast, the PG group did not differ on any of the dimensions from the AD or the GTS group, except for 'choice impulsivity' where the PG group exhibited higher factor scores compared to the GTS group. Altogether, PG is associated with generally heightened impulsivity profiles compared to a HC group, which may be further used for intervention strategies. However, heightened scores in the impulsivity dimensions are not disorder specific for PG. Further research on shared or different underlying mechanisms of these overlapping impulsivity impairments is necessary.

[Development of the Subjective Urge Scale and its usefulness in people with tic disorders]

The impulsivity of people with tic disorder has been a recent focus of attention. This study aimed to investigate this phenomenon in people with and without tics in a non-clinical setting, focusing on the subjective urge experienced prior to impulsive behavior. In Study 1, we created a scale to measure the strength of subjective urges. This scale, which was found to comprise three subscales, had high internal consistency and high generalizability. In Study 2, using the scale developed in Study 1, we showed that people with tics felt stronger subjective urges than people without tics. This suggests that the relation between tics and impulsivity exists not only among people in clinical settings but also in non-clinical settings. Also, subjective urges significantly affect the severity of depression and this elfect was pronounced in people with tics in this study. Thus. we should consider the presence or absence of tics when we discuss impulsivity, in particular the effect of subjective urges on depression.

Pediatric Tourette syndrome: insights from recent neuroimaging studies

Tourette syndrome has been examined using many different neuroimaging techniques. There has been a recent surge of neuroimaging research papers related to Tourette syndrome that are exploring many different aspects of the disorder and its comorbidities. This brief review focuses on recent MRI-based imaging studies of pediatric Tourette syndrome, including anatomical, functional, resting state, and diffusion tensor MRI techniques. Consistencies across studies are explored, and particularly important issues involved in acquiring data from this special population are discussed.

Social reasoning in Tourette syndrome

INTRODUCTION

Tourette syndrome (TS) is thought to be associated with striatal dysfunction. Changes within frontostriatal pathways in TS could lead to changes in abilities reliant on the frontal cortex. Such abilities include executive functions and aspects of social reasoning.

METHODS

This study aimed to investigate executive functioning and Theory of Mind (ToM; the ability to reason about mental states, e.g., beliefs and emotions), in 18 patients with TS and 20 controls. A range of tasks involving ToM were used. These required participants to make judgements about mental states based on pictures of whole faces or the eyes alone, reason about humour in cartoons that featured sarcasm, irony or "slapstick" style humour, and make economic decisions. The executive measures assessed inhibition and verbal fluency.

RESULTS

Patients with TS exhibited significantly poorer performance than controls on all four tasks involving ToM, even when patients with comorbid obsessive-compulsive disorder were excluded. These difficulties were despite no inhibitory deficits. Patients with TS exhibited impairment on the verbal fluency task but their performance on executive and ToM tasks was not related.

CONCLUSIONS

We propose that TS is associated with changes in ToM. The observed deficits could reflect dysfunction in frontostriatal pathways involving ventromedial prefrontal cortex.

Tourette-like behaviors in the normal population are associated with hyperactive/impulsive ADHD-like behaviors but do not relate to deficits in conditioned inhibition or response inhibition

Attention-Deficit Hyperactivity Disorder (ADHD) and Tourette Syndrome (TS) present as distinct conditions clinically; however, comorbidity and inhibitory control deficits have been proposed for both. Whilst such deficits have been studied widely within clinical populations, findings are mixed—partly due to comorbidity and/or medication effects—and studies have rarely distinguished between subtypes of the disorders. Studies in the general population are sparse. Using a continuity approach, the present study examined (i) the relationships between inattentive and hyperactive/impulsive aspects of ADHD and TS-like behaviors in the general population, and (ii) their unique associations with automatic and executive inhibitory control, as well as (iii) yawning (a proposed behavioral model of TS). One hundred and thirty-eight participants completed self-report measures for ADHD and TS-like behaviors as well as yawning, and a conditioned inhibition task to assess automatic inhibition. A sub-sample of fifty-four participants completed three executive inhibition tasks. An exploratory factor analysis of the TS behavior checklist supported a distinction between phonic and motor like pure TS behaviors. Whilst hyperactive/impulsive aspects of ADHD were associated with increased pure and compulsive TS-like behaviors, inattention in isolation was related to reduced obsessive-compulsive TS-like behaviors. TS-like behaviors were associated with yawning during situations of inactivity, and specifically motor TS was related to yawning during stress. Phonic TS and inattention aspects of ADHD were associated with yawning during concentration/activity. Whilst executive interference control deficits were linked to hyperactive/impulsive ADHD-like behaviors, this was not the case for inattentive ADHD or TS-like behaviors, which instead related to increased performance on some measures. No associations were observed for automatic conditioned inhibition.