Deficits in motor control processes involved in production of graphic movements of children with attention-deficit-hyperactivity disorder.

This study aimed to investigate whether two distinct motor control processes, i.e. motor planning and parameter setting, were impaired in children with attention-deficit-hyperactivity disorder (ADHD). An experiment was designed in which children copied figures of increasing complexity under increasing accuracy levels on a digitizer. Sixteen children with ADHD (11 males, 5 females; mean age 8y 4mo, SD 1y 1mo) and 16 comparison children, without impairment, matched for age and sex participated. ADHD was diagnosed by a psychiatrist following the criteria of the DSM-V. Only children with IQ scores greater than 80 were included. Across all graphic tasks, children with ADHD made slower, inaccurate strokes with relatively high axial pen force compared with the comparison group. No evidence was found for a deficit in motor planning, but parameter setting appeared to be deficient as the ADHD group made less accurate strokes when accuracy demands increased.