Diagnosis, the rate-limiting factor of biological depression research.

The third edition of the DSM provided a standardized, operationalized classification system of mood disorders. In this paper, the question is raised whether this system is a good starting point for biological depression research. The question is answered in the negative and the reasons why are being discussed. The proposed mood disorders are not properly validated and utterly heterogeneous and overlapping. An etiological axis is wanting and no hypothesis as to the relations between axis I and II diagnoses is required. The comorbidity problem is not satisfactorily resolved. The system leaves no room for a dimensional/functional analysis of mood and personality disorders. The frequent revisions that are only to a small extent based on preconceived research, lead to havoc in the research arena. The DSM III classification is considered to be the single most important factor hampering biological depression research. Ways to remedy the situation are pointed out.