Melancholia and catatonia: disorders or specifiers?

The fifth version of the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 defines mental disorders as syndromes and also introduced disorder "specifiers" with the aim of providing increased diagnostic specificity by defining more homogeneous subgroups of those with the disorder and who share certain features. While the majority of specifiers in DSM-5 define a specific aspect of the disorder such as age at onset or severity, some define syndromes that appear to meet the DSM-5 definition of a mental disorder. Specifically, melancholia is positioned in DSM-5 as a major depressive disorder (non-coded) specifier, while catatonia is listed as both a disorder secondary to a medical condition and as a specifier associated with other mental disorders such as schizophrenia, major depressive disorder, and bipolar disorder. Despite decades of research supporting melancholia's status as a categorical "disorder" (a higher-order construct than a specifier), failure to provide convincing support for its disorder status has contributed to its current positioning in DSM-5. As DSM-5 has similar symptom criteria for major depression and for its melancholia specifier, research seeking to differentiate melancholic and non-melancholic depression according to DSM-5 criteria will have limited capacity to demonstrate "melancholia" as a separate disorder and risks melancholia continuing to be reified as a low-order specifier and thus clinical marginalization. There have been few advances in catatonia research in recent years with its positioning largely relying on opinion and clinical observation rather than on empirical studies.