Disturbances in programming goal-directed arm movements in children with ADHD.

We investigated in children with attention-deficit-hyperactivity disorder (ADHD) the ability to programme and execute goal-directed arm movements. The sample consisted of 25 males with ADHD (mean age 11 years 6 months, SD 1 year 11 months, range 8 to 15 years) and 25 age-matched typically developing males. The children moved a cursor on a screen by moving a hand-held indicator on a horizontal digitizing tablet. Start and target positions on the screen were always visible during the movement. The screen cursor, however, could either be visible throughout the movement (visual feedback) or blanked at movement initiation (without visual feedback). Analysis showed that movement control was impaired in children with ADHD and that their problems were especially pronounced during the without-visual-feedback condition. In this condition, the children with ADHD exhibited large end-point errors and prolonged movement durations. As there can be no visual corrections of the movement during this condition, results indicate poorer motor programming in children with ADHD. Moreover, children with ADHD performed jerky movements and showed a reduced capacity to select a movement speed that met with the accuracy demands of the movement.