Psychiatric Diagnosis and Classification - ResearchGate

8 PSYCHIATRIC DIAGNOSIS AND CLASSIFICATION
...at the present state of knowledge, there appears to be a much closer
connection between aetiology and syndrome in somatic medicine than in
psychiatry . . . while in somatic medicine it is an advantage that aetiologic
diagnoses take the place of syndromes, in psychiatric classification, aetiology
can never be allowed to replace syndrome ...asystem of double diagnosis, one
of aetiology and one of syndrome, has to be used [19].
Can the Classification of Mental Disorders be a Biological
Classification
In this era of unprecedented advances in genetics, molecular biology and
neuroscience, theoretical thinking in psychiatry tends increasingly towards
biological explanatory models of mental disorders. Accordingly, biological
classifications are increasingly seen as a model for the future evolution of
psychiatric classification.
Classifying involves forming categories, or taxa, for ordering natural
objects or entities, and assigning names to these. Ideally, the categories of
a classification should be jointly exhaustive, in the sense of accounting for all
possible entities, and mutually exclusive, in the sense that the allocation
of an entity to a particular category precludes the allocation of that entity
to another category of the same rank. In biology, despite continuing arguments
between proponents of evolutionary systematics, numerical taxonomy
and cladistics, there is agreement that classifications reflect fundamental
properties of biological systems and constitute ``natural'' classifications.
However, psychiatric classifications and biological classifications are dissimilar
in important respects. First, as pointed out above, the objects that
are being classified in psychiatry are explanatory constructs, i.e. abstract
entities rather than physical organisms. Secondly, the taxonomic units of
``disorders'' in DSM-IV and ICD-10 do not form hierarchies and the current
psychiatric classifications contain no supraordinate, higher-level organizing
concepts.
DSM-IV and ICD-10 are certainly not systematic classifications in the
usual sense in which that term is applied in biology. A closer analogue to
current psychiatric classifications can be found in the so-called indigenous
or ``folk'' classifications of living things e.g. animals in traditional rural
cultures) or other material objects. ``Folk'' classifications do not consist of
mutually exclusive categories and have no single rule of hierarchy but may
have many rules that can be used ad hoc). Such naturalistic systems seem to
retain their usefulness alongside more rigorous scientific classifications
because they are pragmatic and well adapted to the needs of everyday life
[16]. Essentially, they are augmented nomenclatures, i.e. lists of names for
conditions and behaviors, supplied with explicit rules about how these