Because externalizing and internalizing problems often co-occur, it is useful to examine the relations of EC and impulsivity with behavior problems in sample of children with and without co-occurring problem behaviors. It has been argued that disinhibition may contribute to comorbidity between disorders in the externalizing and internalizing spectrum (Krueger & Markon, 2006). Nonetheless, it is important to know whether deficits in regulation/control characterize externalizing or internalizing problem behaviors when they are pure (not co-occurring) or primarily when co-occurring. For example, children with externalizing symptoms may be prone to impulsivity, but only if they are not high in internalizing symptoms.
