Response inhibition and disruptive behaviors: toward a multiprocess conception of etiological heterogeneity for ADHD combined type and conduct disorder early-onset type.

Response disinhibition is one of several processes that may account for disruptive behavior problems. It is associated with both attention deficits/hyperactivity (ADHD-C) and early onset, unsocialized conduct disorder (CD-E). Response inhibition is not a unitary construct. It is best understood via a dual process model of regulatory control. Executive inhibition refers to deliberate suppression of immediate motor behavior in the service of a distal goal in working memory, with relatively low anxiety activation. It is instantiated in the same frontal-striatal-thalamic neural loops as executive function and corresponds in temperament theory to effortful control. Motivational or reactive inhibition refers to anxiety-provoked interruption of behavior in the context of unexpected, novel, or punishment-cue indicators. Along with reward-response and hostile/angry response it corresponds to reactivity in temperament theory, and invokes limbic responsivity. With regard to these types of inhibitory control, ADHD-combined type is predominantly associated with dysfunctional executive inhibition. CD-E is predominantly associated with dysfunctions in the motivational inhibition process, with smaller, secondary effects in executive control. However, in both syndromes etiological heterogeneity is notable. For example, recent evidence indicates that executive inhibitory control is familial, but characterizes only a subset of children with ADHD-C. Recent dual-process models for both ADHD-C and CD-E are therefore important; they are noted and integrated. Examination of the correlates of behavioral inhibition in the subgroups with these inhibitory deficits may prove fruitful in clarifying the diverse routes to disruptive psychopathology in children.