Neurobiological models in postpartum affective disorders

Motherhood is one of the most critical period in women life; in particular, the months following childbirth are a time of heightened vulnerability to depressive mood changes, which can range from maternity blues to postpartum psychosis. Causality of those disorders is still unclear; however, the abrupt and dramatic changes occurring in hormone levels after delivery suggest an important role of hormonal factors in determining postpartum mood alterations. Many authors have focused their attention on the massive drop in blood levels of gonadal steroids after delivery, hypothesizing that postpartum mood changes are caused by the withdrawal of these hormones. Evidences from these studies, which are reported in the first part of the article, are not conclusive; it seems clear, however, that hormonal changes, even not being the single cause of mood disorders, can trigger, in a subgroup of vulnerable women, pathological mechanisms involving many neurotransmitters or their receptors and resulting in depression. In the second part of the article other hormonal changes associated with childbirth are considered, with particular reference to hypothalamic-pituitary-adrenal (HPA) axis, thyroid hormones and prolactin. Then, recent findings about the role of changes of cholesterol and fatty acids blood levels and sleep-wake cycle in postpartum mood disorders are presented. In the final part of the review the authors attempt to build up an integrative model which, considering the data previously discussed, can provide a basis for the understanding of the relationship between neurobiological changes in the postpartum and the development of mood disorders.