Development of Performance and ERPs in a Flanker Task in Children and Adolescents with Tourette Syndrome-A Follow-Up Study

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

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.

P3b Amplitude and Latency in Tic Disorders: A Meta-Analysis

P3b is an event-related potential (ERP) that may be abnormal in patients with tic disorders (TD), but evidence has been inconsistent. Given the possible association between P3b and TD and the need for biomarkers for TD, the primary objective of this meta-analysis was to characterize P3b in patients with TD in comparison to healthy controls (HCs).

METHODS

By searching PubMed, Embase, Web of Science, SCOPUS, Medline, and Google Scholar, we identified studies that compared P3b between TD patients and HCs. The amplitude and latency of P3b were then analyzed. Subgroup analyses were conducted to investigate the influence of different experimental factors on P3b indices.

RESULT

Overall, 19 articles involving 388 cases and 414 controls were evaluated. There were no significant abnormalities in P3b amplitude and latency in TD patients. The P3b amplitude of the TD patients was significantly decreased during the oddball task, and the P3b amplitude of the adult TD patients was also significantly decreased.

CONCLUSION

TD patients may have an abnormal P3b compared to HCs under specified conditions.

Co-Occurrence of Tic Disorders and Attention-Deficit/Hyperactivity Disorder-Does It Reflect a Common Neurobiological Background?

BACKGROUND

The co-existence of tic disorders and attention-deficit/hyperactivity disorder (TD + ADHD) has proven to be highly important in daily clinical practice. The factor ADHD is not only associated with further comorbidities, but also has a long-term negative psychosocial effect, while the factor TD is usually less disturbing for the major part of the patients. It remains unclear how far this is related to a different neurobiological background of the associated disorders or whether TD + ADHD reflects a common one.

OBJECTIVE

This review provides an update on the neurobiological background of TD + ADHD in order to better understand and treat this clinical problem, while clarifying whether an additive model of TD + ADHD holds true and should be used as a basis for further clinical recommendations.

METHOD

A comprehensive research of the literature was conducted and analyzed, including existing clinical guidelines for both TD and ADHD. Besides genetical and environmental risk factors, brain structure and functions, neurophysiological processes and neurotransmitter systems were reviewed.

RESULTS

Only a limited number of empirical studies on the neurobiological background of TD and ADHD have taken the peculiarity of co-existing TD + ADHD into consideration, and even less studies have used a 2 × 2 factorial design in order to disentangle the impact/effects of the factors of TD versus those of ADHD. Nevertheless, the assumption that TD + ADHD can best be seen as an additive model at all levels of investigation was strengthened, although some overlap of more general, disorder non-specific aspects seem to exist.

CONCLUSION

Beyond stress-related transdiagnostic aspects, separate specific disturbances in certain neuronal circuits may lead to disorder-related symptoms inducing TD + ADHD in an additive way. Hence, within a classificatory categorical framework, the dimensional aspects of multilevel diagnostic-profiling seem to be a helpful precondition for personalized decisions on counselling and disorder-specific treatment in TD + ADHD.

Compromised reactive but intact proactive inhibitory motor control in Tourette disorder

Tourette disorder (TD) is characterized by tics, which are sudden repetitive involuntary movements or vocalizations. Deficits in inhibitory control in TD patients remain inconclusive from the traditional method of estimating the ability to stop an impending action, which requires careful interpretation of a metric derived from race model. One possible explanation for these inconsistencies is that race model's assumptions of independent and stochastic rise of GO and STOP process to a fixed threshold are often violated, making the classical metric to assess inhibitory control less robust. Here, we used a pair of metrics derived from a recent alternative model to address why stopping performance in TD is unaffected despite atypical neural circuitry. These new metrics distinguish between proactive and reactive inhibitory control and estimate them separately. When these metrics in adult TD group were contrasted with healthy controls (HC), we identified robust deficits in reactive control, but not in proactive control in TD. The TD group exhibited difficulty in slowing down the speed of movement preparation, which they rectified by their intact ability to postpone the movement.

Post-error adjustment among children aged 7 years with a familial high risk of schizophrenia or bipolar disorder: A population-based cohort study

The cognitive control system matures gradually with age and shows age-related sex differences. To gain knowledge concerning error adaptation in familial high-risk groups, investigating error adaptation among the offspring of parents with severe mental disorders is important and may contribute to the understanding of cognitive functioning in at-risk individuals. We identified an observational cohort through Danish registries and measured error adaptation using an Eriksen flanker paradigm. We tested 497 7-year-old children with a familial high risk of schizophrenia (N = 192) or bipolar disorder (N = 116) for deficits in error adaptation compared with a control group (N = 189). We investigated whether error adaptation differed between high-risk groups compared with controls and sex differences in the adaptation to errors, irrespective of high-risk status. Overall, children exhibited post-error slowing (PES), but the slowing of responses did not translate to significant improvements in accuracy. No differences were detected between either high-risk group compared with the controls. Boys showed less PES and PES after incongruent trials than girls. Our results suggest that familial high risk of severe mental disorders does not influence error adaptation at this early stage of cognitive control development. Error adaptation behavior at age 7 years shows specific sex differences.

Electrophysiology Echoes Brain Dynamics in Children and Adolescents With Tourette Syndrome-A Developmental Perspective

The development of the complex clinical picture of motor and vocal tics in children and adolescents with Tourette syndrome (TS) must be paralleled by changes in the underlying pathophysiology. Electrophysiological methods such as EEG and event-related potentials (ERPs) are non-invasive, safe and easy to apply and thus seem to provide an adequate means to investigate brain dynamics during this brain maturational period. Also, electrophysiology is characterized by a high time resolution and can reflect motor, sensory and cognitive aspects as well as sleep behavior. Hence, this narrative review focuses on how electrophysiology echoes brain dynamics during development of youngsters with TS and might be useful for the treatment of tics. A comprehensive picture of developmental brain dynamics could be revealed showing that electrophysiological parameters evolve concurrently with clinical characteristics of TS. Specifically, evidence for a maturational delay of motor inhibition related to cortico-spinal hyper-excitability and brain mechanisms for its cognitive compensation could be shown. Moreover, deviant sleep parameters and probably a stronger perception-action binding were reported. For neuromodulatory treatments (e.g., neurofeedback; repetitive transcranial magnetic stimulation, rTMS/transcranial direct current stimulation, tDCS) targeting neuronal deficits and/or strengthening compensatory brain mechanisms, pilot studies support the possibility of positive effects regarding tic reduction. Finally, attention-deficit/hyperactivity disorder (ADHD), as a highly frequent co-existing disorder with TS, has to be considered when using and interpreting electrophysiological measures in TS. In conclusion, application of electrophysiology seems to be promising regarding clinical and research aspects in youngsters with TS.

Tic frequency and behavioural measures of cognitive control are improved in individuals with Tourette syndrome by aerobic exercise training

Previous observations of improvements in cognition in typically developing children following moderate to vigorous exercise (e.g., Budde, Voelcker-Rehage, Pietrabyk-Kendziorra, Ribeiro, & Tidow, 2008; Hillman et al., 2009) have led to increased interest in the potential benefits of exercise for children with neurodevelopmental disorders, involving difficulties in self-regulation (e.g., Halperin & Healey, 2011; Archer & Kostrzewa, 2012). Using a within-sample design, the current study looked at the beneficial effects of non-aerobic movement training (Tai Chi), compared to aerobic movement training (Kick Boxing), on behavioural measures of cognitive control and clinical measures of tic severity in a group of young people with Tourette Syndrome (TS). We demonstrate that Kick Boxing, but not Tai Chi, led to a significant enhancement in cognitive control task performance. Furthermore, while tic frequency (tics per minute) was reduced during both types of exercise, this reduction was significantly greater, and sustained for longer, following Kick Boxing. Importantly, the magnitude of the increase in cognitive control following Kick Boxing predicted the degree of reduction in tic frequency. These findings suggest that aerobic exercise may be a useful intervention for improving self-regulation of tics in young people with TS, probably through enhancements in associated cognitive control circuits.

A superior ability to suppress fast inappropriate responses in children with Tourette syndrome is further improved by prospect of reward

In children with Tourette syndrome (TS), tics are often attributed to deficient self-control by health-care professionals, parents, and peers. In this behavioural study, we examined response inhibition in TS using a modified Simon task which probes the ability to solve the response conflict between a new non-spatial rule and a highly-overlearned spatial stimulus-response mapping rule. We applied a distributional analysis to the behavioural data, which grouped the trials according to the individual distribution of reaction times in four time bins. Distributional analyses enabled us to probe the children's ability to control fast, impulsive, responses, which corresponded to the trials in the fastest time bin. Additionally, we tested whether the ability to suppress inappropriate action tendencies can be improved further by the prospect of a reward. Forty-one clinically well-characterized medication-naïve children with TS, 20 children with attention-deficit/hyperactivity disorder (ADHD), and 43 typically developing children performed a Simon task during alternating epochs with and without a prospect of reward. We applied repeated measures ANCOVAs to estimate how the prospect of reward modulated reaction times and response accuracy, while taking into account the distribution of the reaction times across trials. We found between-group differences in accuracy when subjects responded relatively fast. The TS group responded more accurately than typically developing control children when resolving the response conflict introduced by the Simon task. The opposite pattern was found in children with ADHD. Prospect of reward improved accuracy rates in all groups. Although the Tourette group performed with superior accuracy in the fast trials, it was still possible for them to benefit from prospect of reward in fast trials. The findings corroborate the notion that children with TS have an enhanced capacity to inhibit fast inappropriate response tendencies. This ability can be improved further by offering a prospect of reward which might be useful during non-pharmacological therapeutic interventions.

Event-Related-Potential (ERP) Correlates of Performance Monitoring in Adults With Attention-Deficit Hyperactivity Disorder (ADHD)

Introduction: Attention-deficit hyperactivity disorder (ADHD) is one of the most frequent neurodevelopmental disorders in children and tends to persist into adulthood. Evidence from neuropsychological, neuroimaging, and electrophysiological studies indicates that alterations of error processing are core symptoms in children and adolescents with ADHD. To test whether adults with ADHD show persisting deficits and compensatory processes, we investigated performance monitoring during stimulus-evaluation and response-selection, with a focus on errors, as well as within-group correlations with symptom scores. Methods: Fifty-five participants (27 ADHD and 28 controls) aged 19-55 years performed a modified flanker task during EEG recording with 64 electrodes, and the ADHD and control groups were compared on measures of behavioral task performance, event-related potentials of performance monitoring (N2, P3), and error processing (ERN, Pe). Adult ADHD Self-Report Scale (ASRS) was used to assess ADHD symptom load. Results: Adults with ADHD showed higher error rates in incompatible trials, and these error rates correlated positively with the ASRS scores. Also, we observed lower P3 amplitudes in incompatible trials, which were inversely correlated with symptom load in the ADHD group. Adults with ADHD also displayed reduced error-related ERN and Pe amplitudes. There were no significant differences in reaction time (RT) and RT variability between the two groups. Conclusion: Our findings show deviations of electrophysiological measures, suggesting reduced effortful engagement of attentional and error-monitoring processes in adults with ADHD. Associations between ADHD symptom scores, event-related potential amplitudes, and poorer task performance in the ADHD group further support this notion.

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.