Effects of dual tasking and methylphenidate on gait in children with attention deficit hyperactivity disorder.

Effects of dual tasking on motor processes such as gait have been mainly investigated with healthy adults and clinical older samples whereas studies with clinical samples of children with attention deficit hyperactivity disorder (ADHD) are rare. Similarly, even though methylphenidate (MPH) is the most often prescribed medication for children with ADHD, the influence of MPH on children's gait under single-task and dual-task situations remains poorly understood. In the current study, children diagnosed with ADHD (n = 26) came twice to the laboratory, once without and once with MPH medication. They were asked to walk over an electronic walkway without a concurrent task (motor single task) and while solving different cognitive tasks (motor-cognitive dual task). Gait variability and cognitive performance were measured. Children's performance was compared to an age- and sex-matched control sample of typically developing children (n = 26) who were also tested twice. Results indicated considerable effects of dual tasking on children's gait irrespective of group (ADHD vs. controls), with children diagnosed with ADHD showing more pronounced gait alterations in dual-task situations as compared to controls. Furthermore, MPH medication in children with ADHD enabled them to substantially decrease their stride time variability to a level that was comparable to the level of typically developing children. Overall, our findings support the notion that higher cognitive processes such as attention and executive functions influence gait and that MPH can positively affect cognitive and motor processes such as gait.