Movement sequencing in children with Tourette's syndrome and attention deficit hyperactivity disorder

Little research has been conducted to examine sequential motor functioning of children with Tourette's syndrome (TS) and attention deficit hyperactivi ty disorder (ADHD). Movement sequencing performance for a group of 12 child ren with TS and 24 children with ADHD children (12 taking and 12 not taking stimulant medication) and matched control subjects was examined using a se rial choice reaction time button-pressing procedure. Aspects of movement pr eparation and execution were measured for 10 sequential two-way choice poin ts along a response board that extinguished the illuminated target buttons at certain specific times contingent on the previous button press or releas e. The level of advance information was systematically reduced to provide t hree levels of reduction of advance information. including no reduction, mo derate reduction, and high reduction. Children with TS and ADHD (unmedicate d) showed larger increases in down time, reflecting aspects of movement pre paration, for the highest level of reduction of advance information than di d their respective control groups. These deficits are suggestive of underly ing frontostriatal dysfunction. Furthermore, the normalization of performan ce for children with ADHD taking stimulant medication assists in the confir mation of the validity of such a clinical diagnosis and seems to add to the clinical efficacy of this form of treatment, which has previously been ass ociated with improvements for predominantly attentional and inhibitory symp toms of ADHD.