The Relationship Between Cortisol Levels and Aggression in Middle Childhood

• Sara Pizzini, Psychology, Georgetown University

• Mary Dozier, Psychological and Brain Sciences, University of Delaware

Dysregulated hypothalamic-pituitary-adrenal (HPA) axis functioning is associated with poor mental and physical outcomes and can be measured through assessment of its end product, cortisol. Aggression in children results from sociocultural and biological factors such as HPA axis functioning. Past research has found that lower concentrations of cortisol is related to externalizing behaviors. However, studies vary in methodology of cortisol sampling (e.g., awakening level, Cortisol Awakening Response, diurnal pattern) and research design (e.g., cross-sectional or longitudinal). There has been little research that assesses HPA axis activity and aggression longitudinally and has considered subtypes of aggression such as reactive aggression. Thus, the present study explored the association between morning cortisol levels at age nine and aggression at age 10. Reactive aggression was measured at age 10 observationally through a video game task and self-reported by the children. Salivary cortisol levels at wake-up were measured across three days in a sample of children in middle childhood (n=178, Mage=10.64) in high (n=107) and low risk (n=71) groups. Linear regressions were run to assess the relationship between morning cortisol levels and reactive aggression while controlling for child sex and age. When accounting for these covariates, morning cortisol levels did not predict the observational report of reactive aggression, but did significantly predict self-reported reactive aggression. Further research should investigate this relationship by measuring aggression and morning cortisol levels concurrently at specific time points for two or more consecutive years to observe if this relationship changes longitudinally.