Physiological Correlates of Aggression in Adolescent Females

Recently, with the development of new technology, researchers have focused on physiological predictors of aggressive behavior, specifically cortisol and alpha amylase. Gordis, Granger, Susman, and Trickett (2006) found the interaction between cortisol and alpha-amylase significantly predicted parent reports of aggression indicating that low levels of physiological reactivity was associated with higher levels of problem behavior. While this research has provided valuable information about aggressive behavior, a major limitation is the majority of research focuses on males, or has not examined gender differences explicitly. This study expanded on work by Gordis et al. (2006) and other researchers on the HPA axis and sympathetic nervous system responses and aggression by using a larger sample, focusing on female adolescents, examining both physical and relational aggression, and utilizing parent and adolescent reports of aggressive behavior. Based on prior literature, I expected that lower levels of salivary cortisol taken at the beginning of the interview and the beginning of the stress task would be associated with higher levels of physical and relational aggression in girls. I also hypothesized that lower levels of cortisol and α-amylase reactivity will be associated with higher levels of physical and relational aggression. Finally, I hypothesized that lower levels of cortisol reactivity coupled with higher levels of α-amylase reactivity will be associated with lower levels of aggressive behavior. Participants in the current study live in moderate- to high-violence areas in Richmond, VA. Participants were 146 adolescent females who were enrolled in a larger longitudinal study on coping with exposure to violence. Most of the adolescents were African-American (91.1%) with a mean age of 13.9 years old (range from 11-17). The changes in physiological responses were monitored during the interview process which included the administration of the Social Competence Interview (SCI). Aggression was measured using the Child Behavior Checklist and Problem Behavior Frequency Scales. In the analyses, I controlled for pubertal status, medication usage, race, and time of day which are all factors that can influence the level of cortisol and alpha-amylase. Results indicated that higher levels of basal cortisol were associated with higher levels of aggressive behavior. In contrast to previous research and prediction, results indicated that symmetry in α-amylase and cortisol predicted lower levels of self-reported physical aggression in girls. Asymmetry in the two systems was associated with higher levels of self-reported physical aggression. These results contribute to the mixed results on female physiological responses and aggression. It also provides support for symmetry in cortisol and α-amylase as a predictor of lower levels of aggressive behavior. Studying a child’s physiological reactions to stress can give insight into behavior regulation, help identify adolescents for prevention/intervention, and serve as markers of treatment progress. These data suggest that physiological associations with aggression may not be the same for males and females, or for youth living in extremely stressful circumstances. Further research is needed to replicate these finding, and specifically to compare these patterns of associations across gender