Unpacking Major Depressive Disorder: From Classification to Treatment Selection

In the past decade, there has been a revival of the debate about diagnostic approaches in mental illness. In 1970, Robins and Guze1 described 5 distinct requirements to justify the diagnosis of a psychiatric syndrome. These involved 1) a consistent clustering of symptoms, 2) laboratory studies to establish a biological substrate, 3) relative specificity of symptoms to distinguish one disorder from another, 4) evidence from follow-up studies of a common course of illness, and 5) some evidence of genetic predisposition based on higher prevalence rates in the families of affected individuals. There are many potential benefits to this approach: internationally accepted taxonomy facilitates studies across multiple research areas, ranging from epidemiology and health economics to disease mechanisms, treatment outcome evaluations, and pursuit of new therapeutics