The biology of postpartum psychosis: A hypothetical model

Abstract

I had the pleasure of meeting Channi Kumar as a junior psychiatry trainee at the Maudsley Hospital, when I elected to work in his clinical service as part of my rotation. It is therefore for me an honour to contribute to a book that celebrates his legacy. While working with him, I had the opportunity to seeing him in both the clinical and the academic settings. I came to know Channi as a gentle and charismatic clinician with patients, and an inspiring scientist. Channi was fascinated by the predictability of postpartum psychosis, which he used to discuss extensively with his patients, and he led seminal work on the biology of this disorder. I have been stimulated by this work and motivated to advance what remains a largely unexplored area of psychiatry. This chapter will discuss evidence on how biological factors relevant to the pathophysiology of psychoses and the perinatal period could interact in explaining the vulnerability and onset of postpartum psychosis. The role of genetic factors is extensively covered in Chapter 18, and will therefore not be discussed here. Psychiatric disorders contribute to 12% of all maternal deaths (UK Confidential Enquiry into Maternal Deaths; RCPG 2002), and puerperal (or postpartum) psychosis is the most severe psychiatric disorder associated with childbirth, with an estimated suicide rate of 2 per 1,000 sufferers (Oates 2003), and an incidence of 1–2/1,000 deliveries (Munk-Olsen et al. 2006). Although the last few decades have seen a fall in mortality and morbidity from childbirth, this has not been paralleled by a fall in the incidence of postpartum psychosis, which has remained remarkably stable at 0.5–1.0 per 1,000 deliveries (Munk-Olsen et al. 2006). Postpartum psychosis can have dramatic clinical and social consequences: child separation from the mother; lack of emotional bonding between mother and child; impaired child cognitive, physical, and psychological development; and, in some cases, suicide, infanticide, or both. This devastating impact is remarkable, especially considering that postpartum psychosis is highly predictable: in fact, between 30 and 50% of women with a history of bipolar affective disorder, or of schizoaffective disorder, will suffer postpartum psychosis after giving birth (Jones and Cradock 2001); and up to 50–70% of women with a previous history of postpartum psychosis (Jones and Craddock 2001).