As described in the literature for many years, a sizable number of children with hyperactive-impulsive and combined subtypes/presentations of attention-deficit/hyperactivity disorder (ADHD)—especially males—progress to more serious externalizing syndromes across development. Such outcomes include oppositional defiant disorder, conduct problems, delinquency, substance use disorders, and in some cases antisocial personality disorder, incarceration, and recidivism. This chapter summarizes a developmental model that emphasizes different contributions of trait impulsivity, a highly heritable, subcortically mediated vulnerability, versus emotion dysregulation, a highly socialized, cortically mediated vulnerability, to externalizing progression. According to this perspective, trait impulsivity confers vulnerability to all externalizing disorders, but this vulnerability is unlikely to progress beyond ADHD in protective environments. In contrast, for children who are reared under conditions of adversity—including poverty, family violence, deviant peer influences, and neighborhood violence/criminality—neurodevelopment of prefrontal cortex structure and function is compromised, resulting in failures to achieve age-expected gains in emotion regulation and other forms of executive control. For these children, subcortical vulnerabilities to trait impulsivity are amplified by deficient cortical modulation, which facilitates progression along the externalizing spectrum.
Instantiating the multiple levels of analysis perspective in a program of study on externalizing behavior
