The Relation of Early Adversity to Trait Depression in Adulthood: The Mediating Role of the Trait Cortisol Awakening Response

The main objective of this study was to explore relations between early adversities and two associated risk factors for depression, trait depression and patterns of HPA axis function. Specifically, the study sought to test whether an indicator of hypothalamic-piuitary-adrenal (HPA) axis function, the cortisol awakening response (CAR), mediates the relation between early abuse and trait depression. No study to date has examined the association of these constructs in the same study at similar conceptual levels (i.e., trait function). Although the CAR has been studied extensively in association with depression and psychosocial variables associated with depression, the research has produced mixed results. Yet it is frequently implied or stated that differences in the CAR may be causally associated with depression. Although this speculation finds some support in animal research, associations between early adversities, the CAR, and dispositional factors such as trait depression cannot be assumed. Thus, the present study sought to advance the literature by exploring the mediating effect of morning cortisol increase (i.e., trait CAR and CAR flexibility) in a model examining the relation between early adversities and trait depression.

Drawing a sample of adults from the Notre Dame Health & Well-Being (NDHWB) study, 144 participants reported their experiences of early abuse and parental care. A focused test of the indirect effect showed a trend for trait CAR and CAR flexibility to statistically mediate the relation between maternal abuse and trait depression. This trend was evident only when the late-life cohort data was excluded from the analyses. The results suggest that the core index of parental abuse, maternal neglect and antipathy, is associated with trait depression and blunted trait CAR and CAR flexibility in early-, mid- and late-life