Functioning in this circuit may differentiate subgroups of youth with conduct disorder. One subgroup has callous–unemotional traits and shows reduced amygdala function when performing tasks that engage either empathic responding or threat assessment. The subgroup without callous–unemotional traits exhibits a different pattern, with atypically elevated threat-circuitry responsiveness,38 a hostile attributional bias,39 and increased risks of anxiety and aggression in reaction to frustration or threat.1 Indeed, patients with conduct problems who do not have callous–unemotional traits, much like patients with anxiety disorders,40 show elevated amygdala responses to threat, as compared with responses in youth free of psychopathology.32 The risk of reactive aggression may be highest when such heightened responses occur in tandem with impulsivity or other features of ADHD. This combination is a feature of many disorders, including intermittent explosive disorder, borderline personality disorder, and disruptive mood dysregulation disorder.41–43 In short, youth with elevated amygdala responsiveness to threat might have different problems over time and different responses to treatment than youth with normal or reduced amygdala responsiveness.
