The clinical presentation, neurcognition and neural correlates of children with a tic disorder

Tourette syndrome (TS) is a common childhood-onset disorder characterized by the presence of sudden, rapid movements and vocalizations (tics). The goal of this thesis was to gain a better understanding of the clinical presentation and neural correlates of tics in children. I focused on two under-investigated clinical topics in TS: precursors of tics and uncomfortable feelings or sensations preceding tics (premonitory urges). Furthermore, I investigated neurocognition in children with TS, in particular in relation to attention-deficit/hyperactivity disorder (ADHD). Children with a tic onset had more severe conduct problems and autism spectrum symptoms, compulsions, and emotional problems compared to children without a tic onset. The results appeared sex-specific, with more severe conduct problems and autism spectrum symptoms in boys, and more severe compulsions, oppositional and emotional problems in girls. Premonitory urges appeared in a large number of children, also in very young children. ADHD symptomatology was associated with impaired cognitive control, inhibitory control and working memory. Neural activity related to inhibitory control appeared predominantly in relation to ADHD symptomatology rather than to tics per se. Finally, I observed a different functional brain network organization in children with TS without comorbid ADHD, compared with healthy controls and children with (comorbid) ADHD. Overall, comorbidity plays a substantial role in the clinical presentation, neurocognitive functioning, and neural correlates of children with tics.