Abstract

The offspring of parents with an affective disorder (OAD) are at high risk of developing mental disorders. This thesis examines the influence of hypothalamic-pituitary-adrenal (HPA) axis functioning and the caregiving environment on the transmission and prevention of psychopathology in the OAD. First, meta-analytic procedures were used to quantitatively summarize studies comparing diurnal cortisol levels in the natural environment in the OAD to control offspring. Relative to controls, the OAD had higher mean levels of cortisol at different timepoints throughout the day (Hedges’ g = .21). These findings suggest that changes in HPA function may predate the onset of a full-blown affective disorder (AD). In the second study, data from a longitudinal study of offspring of parents with bipolar disorder (OBD) was used to study the relations between HPA axis functioning, the caregiving environment, and offspring psychopathology. As expected, the OBD who developed an AD had a higher cortisol awakening response (CAR) than OBD who did not have an AD (Cohen’s d = 0.423) and controls (Cohen’s d = 0.468). Serial mediation analyses revealed that family structure in childhood and the CAR in offspring mediated the relationship between risk status (having a parent with bipolar disorder) and offspring internalizing symptoms 12 years later (CI [.01, .66]). The last study aimed to evaluate the efficacy of the Reducing Unwanted Stress in the Home program using a quasi-experimental design with an assessment-only control group. Assessments were conducted at pre- and post-intervention, and at a three- and six-month follow-up. Multilevel modelling revealed reduced externalizing symptoms in the OBD and enhanced family organization immediately post-intervention. The gains in organization remained at the six-month follow-up, while reductions in family conflict became apparent. Mediation analyses indicated treatment induced changes in organization, but not other aspects of the family environment, were associated with reduced externalizing problems in the OBD at the six-month follow-up. Taken together, HPA abnormalities may represent a biomarker of risk among the OAD which may be shaped, at least in part, by specific, early experiences in the caregiving environment. These findings highlight the need for targeted, developmentally-informed treatments to offset adverse outcomes in the OAD.