Psychiatric Diagnosis and Classification - ResearchGate

38 PSYCHIATRIC DIAGNOSIS AND CLASSIFICATION
everysubject in a rigorous manner. In a studyof 110 outpatient subjects
where all the 112 criteria for DSM-III-R personalitydisorder were scored, 68
patients met the criteria for a total of 155 diagnoses. The presumption
was that none of the subjects could be considered to have a normal personalitysince
all met a substantial number of criteria for personalitydisorders
[35].
The concept of comorbiditybecomes important when the classification
logic posits discrete categories. Comorbidity, the concurrence of more than
one diagnosis, does occur but it can be an artefact of hierarchical rules used
in classification systems. Excessive splitting of classical syndromes into
subtypes of disorders with overlapping boundaries and indefinite thresholds
adds to the confusion. Though the co-occurrence of pathologyin
different subsystems of the body or mind) is indeed contingent, it can be
attributed either to the same underlying etiological cause affecting different
body systems as is the case, for example, with diabetes causing hyperglycemia,
peripheral neuropathyand nephropathy) or to distinct causes that
just happen to co-occur as is the case with diabetes and a lacerated wound
following an injury). Further, the notion of comorbidity can only be
accepted when the categories are not mutuallyexclusive, in order to avoid
categoryerrors. For example, one can be classified as a friend and an enemy
provided it is not to the same person at the same time as these would be
contradictorycategories.
We need to address the issue of comorbiditywith novel research strategies
in experimental psychiatry. The challenge lies in determining when
co-occurring conditions are derived from the same underlying etiology,
where theyare contradictorycategoryerrors and therefore must be disallowed,
and where theyhave an interactive effect on course and outcomes.
Systematic studies are required to understand the frequencies with which
comorbid mental disorders occur, the impact that this has on outcomes and
responses to interventions and on functioning and disability. Commonly
occurring comorbid conditions need to be further evaluated to understand if
theyshare a common etiologyor if theyare downstream effects of one
another or modulating or predisposing factors for each other. For example,
if depression and alcohol use disorders occur commonly, are these the result
of a common ``hyposerotonergic'' state in the brain brought about by a
confluence of genetic factors or is being depressed a psychological state
that then leads on to the behavior of drinking as a coping mechanism that
soon becomes uncontrollable due to the independent physiological effects
of alcohol and in turn depletes serotonin in the brain setting up a cycle
The answers to such questions from the studyof comorbid conditions will
then help categorize such multiple conditions using an organizing principle
that maybe quite different from that in the current classificatory
systems.