Response inhibition in attention-deficit hyperactivity disorder

An overview of a number of different lines of research is presented to demonstrate that problems with response inhibition are involved in attention-deficit hyperactivity disorder (ADHD). Response inhibition is defined as the capacity to delay prepotent responses, to interrupt ongoing responses given feedback about performance, and to inhibit responding to sources of interference when engaged in tasks requiring self-regulation and goal-directed action. A considerable amount of research is explored on each of these aspects of inhibition in both children and adults with ADHD. Results in that literature are reasonably consistent in supporting the assertion that ADHD creates deficiencies in each of the three areas of inhibitory functioning. Such deficits appear to be rather specific to ADHD and do not seem to be caused by other disorders that often coexist with ADHD, such as mood, anxiety, and learning disorders. More research needs to be done, however, on whether or not conduct disorder is also associated with difficulties in behavioral inhibition and, if so, whether they are of the same qualitative nature as those seen in ADHD and are simply not the result of the large overlap of conduct disorder with ADHD. MRDD Research Reviews 1999;5:177–184.