It is rare in the field of biological psychiatry for hypotheses to be definitively refuted. Rather, topics of investigation drift into and out of fashion, often driven by the initial excitement of technological innovation, followed by the necessary corrective of nuanced or underwhelming clinical results. A well-known example of this is the association between depression and abnormal function of the HPA axis, as measured using the dexamethasone suppression test (DSST; 1). This observation led to a great deal of work investigating whether the association might help us identify useful subtypes of depression (2) or predict treatment response (3).