The current study investigated gender differences in types and correlates of aggression among 150 adjudicated youth (M age = 15.2, SD = 1.4). In cluster analysis, consistent with past studies, one aggressive group characterized by moderate levels of reactive aggression and one characterized by high levels of proactive and reactive aggression emerged and these patterns were consistent across gender. For both boys and girls, the combined proactive/reactive aggression cluster showed the greatest levels of aggression, impulsivity, and callous-unemotional traits, supporting a severity over a typology model of proactive and reactive aggression. Girls displayed significantly higher rates of physical and relational aggression than boys. Girls were highly aggressive toward both girls and boys, whereas boys were highly aggressive only toward other boys. Girls also showed multiple indications of severity and emotionality, indexed by higher rates of negative affect, anxiety, distress about social provocations, and empathy.

This study investigated reward responsivity in youth with high levels of callous-unemotional (CU) traits using a cross-sectional design. Whereas deficits in responding to punishment cues are well established in youth with CU traits, it is unclear whether responsivity to rewarding stimuli is impaired as well. Participants were 148 predominantly Caucasian, adjudicated adolescents between the ages of 11 and 17 (M = 15.1, SD = 1.4) who completed the Balloon Analogue Risk Task as part of a larger battery investigating aggression and social information processing. A Reward Responsivity variable was created to capture changes in participants' responding after receiving a reward. A hierarchical regression analysis indicated that higher levels of CU traits significantly predicted less reward responsivity, above and beyond gender, sensation seeking, and impulsivity. Results support Blair's (2004) Integrated Emotion Systems model that proposes individuals with CU traits are impaired in their responsivity to both appetitive and aversive stimuli.

The effect of PCE on externalizing problems may persist into late childhood. The findings highlight the potential importance of including child-based measures of externalizing problems in studies of prenatal exposure.