Childhood interparental conflict and HPA axis activity in young adulthood: examining nonlinear relations.

Relations between early adversity and the neuroendocrine stress response are most often tested in a linear framework. Findings from studies of nonlinear relations between early stress and reactivity in childhood are suggestive, but curvilinear associations between childhood family stress and stress reactivity at later developmental stages remain unexplored. The current study examined curvilinear relations between childhood interparental conflict (IPC) and cortisol reactivity in young adulthood. Participants (n = 91; Mean age = 18.7, SD = .97; 59% White, 25% Hispanic) reported on the frequency and intensity of childhood exposure to IPC and salivary cortisol was sampled before and after a challenging interpersonal role-play task. Significant curvilinear relations were found such that higher total cortisol and cortisol reactivity during the task was observed among youth reporting lower and higher frequency of IPC, suggesting that moderate IPC exposure may be associated with lower cortisol activity at a later developmental stage.