Evaluating callous-unemotional traits may be a consideration for youths with conduct problems.
Amygdala hypoactivation in response to fearful expressions predicted test results indicative of proactive aggression in adolescents with conduct disorders and elevated levels of callous-unemotional traits, according to Leah M. Lozier and her colleagues at Georgetown University in Washington.
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Amygdala hypoactivation in response to fearful expressions predicted test results indicative of proactive aggression in adolescents with conduct disorders and elevated levels of callous-unemotional traits.
The findings, noted in a study of youth with and without conduct disorders, suggest that proactive aggression may result from dysfunctional empathic responses to victim distress.
"To our knowledge, no previous study has simultaneously modeled CU [callous-unemotional] traits and externalizing behaviors in response to fearful expressions and compared the efficacy of this technique to that of group-based analysis. In addition, no prior study has linked the resulting patterns of neural activation to aggressive behavior," the researchers reported in an article published online March 26 in JAMA Psychiatry. (doi:10.1001/jamapsychiatry.2013.4540).
The researchers performed functional MRI scans on 16 healthy controls and on 30 youths with conduct problems, 16 with low CU traits and 14 with high CU traits. Aggressive behavior was assessed via the youth-completed Reactive-Proactive Aggression Questionnaire. Traits were measured based on scores on the Inventory of Callous-Unemotional Traits. Conduct problems were diagnosed based on the Strengths and Difficulties Questionnaire and the Child Behavior Checklist. The tests were performed in all study participants.
During scanning, participants completed an implicit face emotion processing task that involved the use of stimulus images of 10 men and women from the Pictures of Facial Affect series, which display positive-neutral, fearful, and angry expressions.
Based on a multiple-regression analysis across the full sample, responses in the right amygdala were positively associated with externalizing behaviors (x = 24, y = 0, z = -14; k = 8) and negatively associated with CU traits (x = 26, y = 0, z = -12; k = 1).
A second analysis restricted to youths with conduct problems found similar results: Right amygdala activity was positively associated with externalizing behavior (x = 26, y = -4, z = -12; k = 47) and negatively associated with CU traits (x = 26, y = 0, z = -12; k = 1).
The patterns of results were limited to responses to fearful expressions, and not to full-intensity angry expressions and neutral expressions, the researchers said.
They reported no financial disclosures.
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