Like many mental illnesses, the diagnosis of Schizophrenia is based upon the behaviour
of the person being assessed. There is a list of diagnostic criteria which must be
met for a person to be so diagnosed. These depend on both the presence and duration
of certain signs and symptoms.
The most commonly-used criteria for diagnosing Schizophrenia
are from the American Psychiatric Association's Diagnostic & Statistical Manual of
Mental Disorders (DSM) and the World Health Organisation's International Statistical
Classification of Diseases & Related Health Problems (ICD). The most recent versions
are ICD-10 and DSM-IV-TR.
Below is an abbreviated version of the diagnostic criteria
from the DSM-IV-TR.
To be diagnosed as having Schizophrenia, a person must display...
A) Characteristic symptoms
Two or more of the following, each present for a significant portion of time during
a one-month period (or less, if successfully treated):-
- delusions
- hallucinations
- disorganised speech (eg: frequent derailment or incoherence)
- grossly disorganised or catatonic behaviour
- negative symptoms - ie: affective flattening (lack or decline in emotional response),
alogia (lack or decline in speech), or avolition (lack or decline in motivation)
Note: Only one Criterion A symptom is required if delusions are bizarre or hallucinations
consist of hearing voices.
B) Social/occupational dysfunction
For a significant portion of the time since the onset of the disturbance, one or
more major areas of functioning such as work, interpersonal relations, or self-care,
are markedly below the level achieved prior to the onset.
C) Duration
Continuous signs of the disturbance persist for at least six months. This six-month
period must include at least one month of symptoms (or less, if successfully treated)
that meet Criterion A.
Historically, Schizophrenia in the West was classified into Simple, Catatonic, Hebephrenic,
and Paranoid. The DSM now contains five sub-classifications of Schizophrenia. These
are:-
- Catatonic type (where marked absences or peculiarities of movement are present)
- Disorganized type (where thought disorder and flat or inappropriate affect are present
together)
- Paranoid type (where delusions and hallucinations are present but thought disorder,
disorganised behaviour, and affective flattening is absent)
- Residual type (where positive symptoms are present at a low intensity only)
- Undifferentiated type (psychotic symptoms are present but the criteria for Paranoid,
Disorganized, or Catatonic types has not been met)
Symptoms may also be described as 'positive symptoms' (those additional to normal
experience and behaviour) and 'negative symptoms' (the lack or decline in normal
experience or behaviour). 'Positive symptoms' describe psychosis and typically include
delusions, hallucinations and thought disorder. 'Negative symptoms' describe inappropriate
or non-present emotion, poverty of speech, and lack of motivation. In three-factor
models of Schizophrenia, a third symptom grouping, the so called 'disorganisation
syndrome' is also given. This considers thought disorder and related disorganised
behaviour to be in a separate symptom cluster from delusions and hallucinations.
It
is worth noting that many of the positive or psychotic symptoms may occur in a variety
of disorders and not only in Schizophrenia. The psychiatrist Kurt Schneider tried
to list the particular forms of psychotic symptoms which he thought were particularly
useful in distinguishing between Schizophrenia and other disorders which could produce
psychosis. These are called first rank symptoms or Schneiderian first rank symptoms
and include delusions of being controlled by an external force, the belief that thoughts
are being inserted or withdrawn from your conscious mind, the belief that your thoughts
are being broadcast to other people and hearing hallucinated voices which comment
on your thoughts or actions, or may have a conversation with other hallucinated voices.
As with other diagnostic methods, the reliability of 'first rank symptoms' has been
questioned, although they remain in use as diagnostic criteria in many countries.
Developed initially from Wikipedia articles under the GNU Free Documentation Licence
