Is ADHD a disinhibitory disorder?

Attention deficit hyperactivity disorder (ADHD) is widely theorized to stem from dysfunctional inhibitory processes. However, the definition of inhibi tion is imprecisely distinguished across theories. To clarify the evidence for this conception, the author relies on a heuristic distinction between i nhibition that is under executive control and inhibition that is under moti vational control (anxiety or fear). It is argued that ADHD is unlikely to b e due to a motivational inhibitory control deficit, although suggestions ax e made for additional studies that could overturn that conclusion. Evidence for a deficit in an executive motor inhibition process for the ADHD combin ed type is more compelling but is not equally strong for all forms of execu tive inhibitory control. Remaining issues include specificity to ADHD, whet her inhibitory problems are primary or secondary in causing ADHD, role of c omorbid anxiety and conduct disorder, and functional deficits in the inatte ntive ADHD subtype.