Diagnosing and classifying

A diagnosis is the definition of a disorder as to its nature and seat. ‘Nature’ refers to its phenomenology, a etiology and course; ‘seat’ to the underlying pathophysiology. Diagnosing is the process leading to a diagnosis. In classifying a disorder all diagnostic considerations are condensed in a single construct that receives a particular code according to the taxonomy in force.

Classification systems are by no means ‘neutral’, noncommittal. They influence the way disorders are being diagnosed. One is inclined to steer the diagnostic process in such a way as to arrive at a diagnosis that fits the prevailing taxonomy. The impact of classification systems on diagnosing is the more pronounced the more detailed the diagnostic criteria are spelled out. The DSM system is a typical case in point. Diagnostic criteria are stated in great detail and hence the influence of that system on psychiatric diagnosing has been enormous. Diagnoses, so to say, are made with a copy of the DSM (Diagnostic and Statistical Manual of Mental Disorders; DSM–IV: American Psychiatric Association, 1994) in one's hand, or at the least in the back of one's mind.

Diagnosing depression

Basically, there are three ways to characterize psychiatric disorders, in this case depression: the nosological or categorical, the syndromal and the dimensional/functional approaches.