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

Heike Eichele,Lin Sørensen,Steinunn Adolfsdottir,Tom Eichele,Lynn Marquardt,Kerstin J Plessen,Kenneth Hugdahl

doi:10.3389/fnins.2017.00305

Abstract

Background: Tourette Syndrome (TS) is a neurodevelopmental disorder with childhood-onset, with a typical decline in tic severity, as well as an increasing ability to suppress tics in late childhood and adolescence. These processes develop in parallel with general improvement of self-regulatory abilities, and performance monitoring during this age-span. Hence, changes in performance monitoring over time might provide insight into the regulation of tics in children and adolescents with TS.Method: We measured reaction time, reaction time variability, accuracy, and event-related potentials (ERP) in 17 children with TS, including 10 children with comorbid Attention-Deficit/Hyperactivity Disorder (ADHD), 24 children with ADHD, and 29 typically developing children, using a modified Eriksen Flanker task in two testing sessions administered on average 4.5 years apart. We then compared task performance, as well as ERP components across groups, and over time using regression models.Results: Task performance improved in all groups with age, and behavioral differences between children with TS and controls diminished at second assessment, while differences between controls and children with ADHD largely persisted. In terms of ERP, the early P3 developed earlier in children with TS compared with controls at the first assessment, but trajectories converged with maturation. ERP component amplitudes correlated with worst-ever tic scores.Conclusions: Merging trajectories between children with TS and controls are consistent with the development of compensatory self-regulation mechanisms during early adolescence, probably facilitating tic suppression, in contrast to children with ADHD. Correlations between ERP amplitudes and tic scores also support this notion.

Highlights

Tourette Syndrome (TS) is a neurodevelopmental disorder with childhood onset, defined by the presence of multiple motor tics and at least one vocal tic over the period of 1 year or more (American Psychiatric Association, 1994)
Developmental trajectories tended to converge for controls and children with TS during the second assessment where all reaction time differences were minimized (n.s., Figure 1)
Controls responded faster than children with ADHD at the first assessment, and those differences persisted in the second assessment

Summary

Introduction

Tourette Syndrome (TS) is a neurodevelopmental disorder with childhood onset, defined by the presence of multiple motor tics and at least one vocal tic over the period of 1 year or more (American Psychiatric Association, 1994). Compensatory neuromodulatory alterations in brain function possibly evolve through the constant need to suppress tics (Eichele and Plessen, 2013), resulting in increased sustained attention to emerging tics (or urges) and control over motor output/efferents This process is thought to involve activity in a functional network that includes the frontal cortices, basal ganglia, and the thalamic nuclei, the so-called cortico-striatothalamo-cortical circuits (Jackson et al, 2015). Tourette Syndrome (TS) is a neurodevelopmental disorder with childhood-onset, with a typical decline in tic severity, as well as an increasing ability to suppress tics in late childhood and adolescence These processes develop in parallel with general improvement of self-regulatory abilities, and performance monitoring during this age-span.

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