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Slide 1

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The Classification and
Diagnosis of
Schizophrenia Topic 1…read more

Slide 2

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Under the DSM-IVR the diagnosis of
schizophrenia is reliant on the patient
having 2 or more positive symptoms for a
minimum duration of a month
Positive symptoms: an excess or
distortion of normal functioning
Negative symptoms: a loss or
deterioration of normal functioning
Intro…read more

Slide 3

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Positive Symptoms
Negative Symptoms
Bizarre beliefs the individual Affective Flattening
believes are real Individual only expresses a
Experiences of Control smaller range or intensity of
Individual thinks they're emotions
under someone else's control Alogia
Hallucinations Speech suffers to reflect the
Individual see's, hears, slowing or blocking of the
smells or feels things that individuals thought process
aren't real Avolition
Disordered Thinking Individual is no longer or is
Individual thinks thoughts or less goal directed
feelings are being placed into
or taken out of their mind
Types of symptoms…read more

Slide 4

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Reliability: how consistant a measuring instrument is
Inter-rater Reliability Test-retest Reliability
Whether 2 assessors are Whether tests are
likely to give the same consistent over time
Cognitive screening tests
Carson (1991) believed the such as RBANS are
DSMIII from 1980 faced important for diagnosis
this problem and created a because they measure
reliable classification neuropsychological
system impairment
This would mean that there Wilks et al (2003) found
should be greater that RBANS test retest
agreement over diagnosis reliability was as high as
Issues of reliability…read more

Slide 5

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Carson (1991) is Mojtabi + Nicholson It has been found that
criticised because there (1995) criticised the there are massive
is a lack of evidence that specification for diagnosis variations in diagnosis
as being unreliable. between countries
using the DSM III is
used by health clinicians For example a positive Copeland (1971) gave
with high reliability. symptom is `bizarre psychiatrists a description
delusions'. of a patient and in America
In fact Whaley (2001) They asked senior 69% diagnosed this
found that inter-rater psychiatrists to patient with schizophrenia
reliability was as low as differentiate between whilst in the UK only 2%
+.11 bizarre and non bizarre diagnosed this patient with
delusions and there was schizophrenia
This suggests the DSM
III isn't used with high only a +.40 correlation. This shows that there is
The specification lacks low inter-rater reliability
reliability across different cultures.
sufficient reliability
Evaluating the inter-rater reliability…read more

Slide 6

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As measuring cognitive functioning is vital
in diagnosis, the measures test-retest
reliability is also vital.
Prescott et al (1986) measured the test
retest reliability of several cognitive
functioning measures in schizophrenia
patients and found that the results were
reliable over 6 months
This supports Wilks et al
d t h a t RBANS
l ( 2 0 0 3 ) foun h i gh as
e t a s a s
Wilks r e li ab i lity wa
test rete
Evaluating the test-retest reliability…read more

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