Proactive and reactive control of movement are differently affected in Attention Deficit Hyperactivity Disorder...

Attention-Deficit/Hyperactivity Disorder children are impaired in the ability to interrupt an ongoing action in relation to a sudden change in the environment (reactive control, measured by stop signal reaction time, SSRT). Less investigated is the ability to control the response when it is known in advance that it will be required to stop (proactive control, measured by change in Reaction time, RT). The study is aimed at exploring both the reactive and the proactive inhibitory control in a group of ADHD children compared to a group of age-matched controls. ADHD children (N=28) and Controls (N=28) performed 4 tasks: 2 tasks required to respond to the appearance of the go-signals (go task and nostop task) and 2 tasks to respond to the go signals in a context in which sometimes a restrain or suppression of the response was required (go-nogo task and stop task). ADHD children showed a longer SSRT compared to controls. Both groups showed an increment in RT by comparing the go-nogo to the go task and an increment in RT and SD by comparing the stop to the nostop task. ADHD children showed higher intra-individual variability (SD) compared to controls only in the stop and nostop task. ADHD children showed impaired reactive control but preserved proactive control, and the physical appearance of the go signal affected their reaction times intra-individual variability. A comparison between the reactive and proactive controls helps in defining neuropsychological profiles of ADHD children and can inspires therapeutic behavioral-cognitive strategies for response control.