1 Centre for Research in Human Development, Concordia University, Montréal, Canada. Electronic address: mark.ellenbogen@concordia.ca.
2 Centre for Research in Human Development, Concordia University, Montréal, Canada.
3 Département de Psychiatrie et d'Addictologie, Université de Montréal, Montréal, Canada.
4 Douglas Mental Health University Institute, McGill University, Montréal, Canada.
5 Department of Psychology, Emory University, Atlanta, USA.

The offspring of parents with bipolar disorder (OBD) are at high risk for developing affective disorders. Low levels of organization and consistency in the home (parenting structure) is associated with increased behavioral problems and hypothalamic-pituitary-adrenal (HPA) reactivity in the OBD and thus may be an important developmental risk factor. We also examined whether the cortisol response following awakening (CAR) is increased in the OBD who developed an affective disorder relative to OBD with no affective disorder. The sample (19.3 ± 3.4 years) consisted of 68 OBD and 64 offspring (61 female) of parents with no affective disorder (controls). As predicted, offspring who developed an affective disorder had higher CAR than OBD who did not have an affective disorder (Cohen's d= 0.423) and controls (Cohen's d= 0.468). Bootstrapping serial mediation analyses revealed that parenting structure in middle childhood and the CAR in offspring significantly mediated the relationship between risk status and offspring depressive and anxiety symptoms 12 years later (CI:.01,.66). Low parenting structure in the OBD leads to changes in the HPA axis that increases the risk of developing symptoms of an affective disorder. Suboptimal childrearing may have enduring consequences on mental health outcomes in the OBD.