Unique saccadic abilities associated with tourette syndrome: Pure and comorbid groups a controlled study

Tourette Syndrome (TS) is a childhood onset disorder characterized by motor and vocal tics. TS often co-occurs with Attention Deficit Hyperactivity Disorder (ADHD) and Obsessive-Compulsive Disorder (OCD). Since neural networks associated with TS overlap with that of saccadic eye movements, saccadic performance may reflect psychopathology underlying TS+comorbidity. The aims of the present study were to determine whether heterogeneity in TS samples and use of various saccadic conditions are responsible for inconsistent findings. We examined: (1) saccadic behaviour in children groups: TS-only, TS+ADHD, TS+ADHD+OCD and healthy Controls; (2) the effect of different saccadic conditions. Participants (8–16 years) either looked towards (prosaccade) or in the opposite direction (antisaccade) of a peripheral visual stimulus in three conditions: fixation dot disappeared simultaneously (standard), 200ms prior to (Gap200) and 800ms following (Overlap800) stimulus onset. The findings demonstrated that sample heterogeneity and use of various saccadic conditions contribute to inconsistent findings. The TS+ADHD+OCD group displayed an enhanced saccadic ability substantiating the hypothesis of an enhanced adaptive cognitive control in certain groups of children with TS. The TS+ADHD group displayed significantly higher rates of antisaccade errors and unable to reduce their error rates. These findings lend further support to the nosological hypothesis.