Psychiatric Diagnosis and Classification - ResearchGate

6 PSYCHIATRIC DIAGNOSIS AND CLASSIFICATION
these parameters must be shown to form a ``real-world correlational structure''
[16] which is stable and also distinct from other similar structures.
This multivariate set of criteria which can be extended and elaborated
further) implies a polythetic definition of the disease concept, i.e. some,
but not necessarily all, of the criteria must be met. Two issues are of
relevance here. First, the typical progression of knowledge begins with the
identification of the clinical manifestations the syndrome) and the deviance
from the ``norm''; understanding of the pathology and aetiology usually
comes much later. Secondly, there is no fixed point or agreed threshold of
description beyond which a syndrome can be said to be ``a disease''. Today,
Alzheimer's disease, with dementia as its clinical manifestation, specific
brain morphology, tentative pathophysiology, and at least partially understood
causes, is one of the few conditions appearing in psychiatric classifications
that meet the above criteria. Schizophrenia, however, is still better
described as a syndrome.
Thoughtful clinicians are aware that diagnostic categories are simply
concepts, justified only by whether or not they provide a useful framework
for organizing and explaining the complexity of clinical experience in order
to derive predictions about outcome and to guide decisions about treatment.
Unfortunately, once a diagnostic concept like schizophrenia has come into
general use, it tends to become ``reified''Ðpeople too easily assume that it is
an entity of some kind which can be invoked to explain the patient's
symptoms and whose validity need not be questioned. And even though
the authors of nomenclatures like DSM-IV may be careful to point out that
``there is no assumption that each category of mental disorder is a completely
discrete entity with absolute boundaries dividing it from other
mental disorders or from no mental disorder'' [4], the mere fact that a
diagnostic concept is listed in an official nomenclature and provided with
a precise operational definition tends to encourage this insidious reification.
For most of the diagnostic rubrics of DSM-IV and ICD-10 which clearly
do not qualify as diseases), both classifications avoid discussing precisely
what is being classified. DSM-IV explicitly rejects presumably to avoid the
implication of labeling) the ``misconception that a classification of mental
disorders classifies people'' and states that ``actually what are being classified
are disorders that people have'' [4]. The term ``disorder'', first introduced
as a generic name for the unit of classification in DSM-I in 1952, has
no clear correspondence with either the concept of disease or the concept of
syndrome in medical classifications. It conveniently circumvents the problem
that the material from which most of the diagnostic rubrics are constructed
consists primarily of reported subjective experiences and patterns
of behavior. Some of those rubrics correspond to syndromes in the medical
sense, but many appear to be sub-syndromal and reflect isolated symptoms,
habitual behaviors, or personality traits.