Stress Physiology and Post-traumatic Stress Symptoms in Children Exposed to Intimate Partner Violence

Abstract

Intimate partner violence (IPV) is a prevalent problem in families with many children exposed to the violence each year. IPV has been associated with negative outcomes in children including trauma symptoms. A potential avenue to explore to determine which IPV-exposed children are at greatest risk for trauma symptom development is physiological functioning both at baseline and in response to stress. Previous research has demonstrated that trauma exposed children may display atypical physiological functioning of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS). Additionally, atypical physiological functioning has also been associated with maladjustment in children. However, much of this work has focused on the independent effects of the HPA axis and SNS and results have been inconsistent with some finding increased activation, decreased activation or normative functioning associated with poor child outcomes. Bauer and colleagues (2002) argued that these physiological systems need to be examined concurrently to understand which children are at highest risk for maladjustment. Additionally, they put forth two competing models, the interactive (asymmetrical activation is associated with increased risk) and additive (symmetrical functioning is associated with increased risk) models, to describe how the HPA axis and SNS may interact. The present study examined whether the inclusion of both systems best predicts trauma symptoms in IPV-exposed children over the individual effects of each system. Furthermore, it investigates which model, the additive or interactive, best describe the interaction of the two physiological systems. Thirty-five mother-child dyads (children aged 6-12 years) with a history of IPV exposure were included in the study. Children completed a parent-child interaction and mental arithmetic task with saliva samples collected five times over the course of the session. Hierarchical linear regression analyses were conducted to assess whether the interaction between both baseline levels and reactivity levels of cortisol and alpha amylase best predicted child trauma symptoms. Significant interactions were plotted per Aiken and West (1991). Findings supported Bauer et al.'s (2002) suggestion of using a multi-system approach and there was support for both the additive and interactive models. Future directions for research are also discussed.