A tricky object to classify: evidence, postpartum depression and the DSM-IV

The concept of evidence has become central in Western healthcare systems; however, few investigations have studied how the shift toward specific definitions of evidence actually occurred in practice. This paper examines a historical case in psychiatry where the debate about how to define evidence was of central importance to nosological decision making. During the fourth revision of the Diagnostic and Statistical Manual of Mental Disorders a controversial decision was made to exclude postpartum depression (PPD) as a distinct disorder from the manual. On the basis of archival and interview data, I argue that the fundamental issues driving this decision were related to questions about what constituted suitable hierarchies of evidence and appropriate definitions of evidence. Further, although potentially buttressed by the evidence-based medicine movement, this shift toward a reliance on particular kinds of empirical evidence occurred when the dominant paradigm in American psychiatry changed from a psychodynamic approach to a research-based medical model.