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INTRODUCTION In a few psychiatric conditions, there
is there is an underlying physical cause, which is well understood and agreed. This includes, for example:
- Alzheimerís Disease, which is caused by physical degeneration
of specific cells in the brain, leading to dementia
- Downís Syndrome, where the person
is born with 3 copies of chromosome 21, instead of 2, leading to learning disability
In the vast majority of mental
disorders, however, there is no single clear cause. Even in the
examples given, the precise mechanism whereby the physical or chemical
abnormality gives rise to the clinical features is not completely
understood.
It follows therefore, that classification of mental disorder cannot be based on cause alone.
PSYCHIATRIC CLASSIFICATIONS Current international systems
of classifying psychiatric illness such as DSM or ICD (see below) recognise
this. They are essentially descriptive, and do not make assumptions
about the presumed causes of the various illnesses.
They are the cumulative result of many years of research and observation,
and refinement through successive editions. They represent the collective opinions
of experts about how the various categories within them can best be codified
so as to fit as closely as possible the observed patient data.
In practice, "recognised psychiatric illness" nowadays does not mean the views of the (potentially idiosyncratic) individual expert, however eminent. It means
a condition described in one of the two major classifications, DSM or ICD. The
expert does need to refer to one of the classifications in his report.
If a diagnosis is made, the numerical code attached to that diagnosis
should be given. A copy of the section from the ICD or DSM should be
appended to the report. It should go without saying that if the diagnosis of say F32, depressive episode is made, then the clinical features of this condition as laid down by the ICD must be clearly recorded in the report. If this is not the case, the report may appear inconsistent and/or poorly argued, and thence be vulnerable to adverse criticism.
DSM stands for Diagnostic and Statistical Manual
of Mental Disorders - Fourth Edition, known as DSM-IV, of the American
Psychiatric Association.
ICD stands for International Classification of Diseases,
10th Revision, known as ICD10. It is produced by
the World Health Organisation, and is the official classification for the
rest of the world, including the UK NHS.
Availability ICD10 is free online. DSM IV is available by subscription only, though unofficial
versions do exist on the internet.
DSM vs ICD Until the publication of DSMIII in 1980, US psychiatry,
as previously indicated, was heavily influenced by Freudian and other psychoanalytic
theories. Although of continuing interest to many, these theories are now agreed
to be without scientific basis.
DSM since then has "caught up" with
ICD in eschewing theory in favour of observation. It has gained in influence
relative to ICD, possibly outstripping it in certain aspects, such as its multiaxial
system (see below). DSM has also brought to prominence now-familiar terms such as "major
depression" and "PTSD".
DSM is sometimes seen as more rigourous,
in that, as set out on page xxx of the introduction, it requires that, in order to constitute
a diagnosis, symptoms should be not just "an understandable reaction",
bearing in mind the person's culture and circumstances. This introduces a threshold,
which has to be crossed for symptoms to constitute a diagnosis.
ILLNESS OR UNDERSTANDABLE REACTION? Although the point is
not made as explicitly in the ICD as it is in the DSM, the distinction between
illness and understandable reaction is a very important one in routine clinical
practice, where it must be made every day. It is also vital in medicolegal
work. Not everyone, for example, who is upset after an accident, is necessarily
diagnosable with a mental disorder.
DSM IS MULTIAXIAL Unlike ICD, which has just one ěaxisî on
which to code for mental disorder, DSM has 5 axes. Axis I: mental illnesses, an illness being defined as a state of impaired health with a clear onset following a period of normal function.
Axis II: for recording (in the jargon, "coding") the presence or absence of personality disorder(s) and learning disability
(the latter was formerly called mental handicap or retardation); here,
the abnormalities are permanent, and are apparent from adolescence or
earlier.
Axis III: Physical health problems.
Axis IV: Psychosocial and Environmental Problems
"is for reporting psychosocial and environmental stressors that may
affect the diagnosis, treatment, and prognosis of mental disorders".
Axis V: Global Assessment of Functioning Scale
"is for reporting the clinician's judgement of the individual's overall
level of functioning and carrying out activities of daily living. This
information is useful in planning treatment and measuring its impact,
and in predicting outcome."
The DSM is sometimes referred to in reports, though usually just relating
to Axis I. Reports should explain the terms DSM and ICD, and why they are being
used.
Both classifications are regarded
as valid for UK use. The ICD is the official classification for the UK
NHS. It would not be generally accepted that one was better than the
other for medicolegal purposes.
CAVEATS CONCERNING DSM AND ICD These systems are guides only,
describing "conditions coming to the attention of psychiatrists".
They are designed to summarise the assessment of the clinician, and to improve
research and communication.
They were not designed specifically for medicolegal use. They are not intended for lay use; they are not "cookbooks", which
dispense with the need for the psychiatric expert, any
more than a collection of law books makes the services of a lawyer unnecessary. Thus, ICD
and DSM are only properly used when they are interpreted by the
seasoned clinician in the light of experience and expertise.
"Best estimates" rather immutable scientific truths, there are differences
between DSM and ICD, and between successive editions. They are ultimately no
more than continually developing consensus statements of committees of researchers, but nevertheless
do form a useful summary of the "state of the art".
Real patients seldom fit with complete neatness into the categories; indeed,
patients may have more than one diagnosis, as the categories are not mutually
exclusive.
PSYCHOSIS VS. NEUROSIS is another key concept in understanding the classification systems.
PSYCHOSIS In
psychosis (e.g. schizophrenia), the patient has lost touch with
reality. They experience delusions (unshakeable false beliefs) and/or
unreal perceptions (e.g. hallucinations such as hearing voices when
no-one is around). The connections between their thoughts may be
disrupted ("formal thought disorder"). This is a severe illness, and
approximates to the lay idea of "madness". The patient does not realise
that they are unwell ("lacks insight").
ěPsychosisî and ěpsychoticî are
still ěrespectableî terms, widely used in clinical practice and
in the ICD and DSM.
NEUROSIS by
contrast, is generally less severe and much more common. The patient is
free from delusions and hallucinations- they know that their worries or
depressive thoughts, for example, are excessive for the reality of the
circumstances, and therefore recognise them as irrational. The vast
majority of cases of anxiety and depression are of this type.
Use
of terms such as "neuroticî or "neurotic depression" is
less frequent because of the pejorative connotations the word has accquired
in lay use. (this is a frequent occurrence in psychiatry; "paranoid" is the
latest escapee from the textbooks to the street. Even "lunatic" was
originally a technical term.) Accordingly,
the word neurotic or neurosis, would not be used frequently in clinical
or medicolegal practice. The distinction between psychotic and
nonpsychotic states remains vitally important, however, but normally,
the presence of psychosis will be made clear in the report.
The word ěneurosisî still occurs in the ICD, though not the DSM,
as part of the rather unwieldy title ěNeurotic, stress-related and somatoform
disorders.î
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