Schizophrenia
Notes
Paper 3 - Section C
,Schizophrenia
Classification and diagnosis
- Mental disorders are organised in categories so they can be accurately identified
- SZ is classified as a psychotic disorder (others are mood, eating and anxiety…)
- Psychosis is broadly defined as a loss of contact with reality
- Clinicians match p’s symptoms to clinical characteristics in the classification system
- This produces a diagnosis
Classification of SZ → Clinical characteristics
Criterion A: 2 (or more) of the following (only 1 if delusions are bizarre / auditory
hallucinations) each present for a significant portion of time during a 1 month period:
Delusions of persecution: belief people are plotting against them, often
Misinterpretation trying to kill them e.g. milkman is trying to kill them
of sensory info
of grandeur: belief they’re someone famous / important e.g.
believing they are Jesus
Hallucinations visual: seeing things that are not there
Sensory experience
auditory: hearing voices
in absence of real
stimulus tactile: feeling like something’s touching you/ skin when it’s not
Disorganised ‘word salads’: jumbled, ungrammatical speech e.g. ‘colourless
speech green ideas sleep furiously’
neologisms: creating new words e.g. ‘norks are going to get me’
Disorganised violating social norms: e.g inappropriately dressed (the ‘bag lady’
Behaviour image) / inappropriate gestures e.g. repetitive gestures at people
Catatonic rocking / maintaining uncomfortable positions for a long time
Behaviour fixed glare
Negative speech poverty (alogia): lack of additional, unprompted speech
symptoms
Avolition (aka apathy): loss of motivation / goal oriented behaviour
and results in lowered activity levels
flat affect: (affective flattening) failure to show emotional
response when expected e.g. no response to family member dying
Criterion B One (or more) major areas of functioning e.g as work, self-care,
Social / Occupational interpersonal relations are markedly below normal levels
Dysfunction
Criterion C Continuous signs of disturbance last at least 6 months
Duration 6 month period must include at least 1 month of symptoms that
meet Criterion A
POSITIVE SYMPTOMS → ADDITIONAL experiences / symptoms beyond what is normal
NEGATIVE SYMPTOMS → LOSS of usual abilities and experiences
,Reliability and validity in diagnosis and classification of schizophrenia
Key issues: reliability, validity, labelling, commodity, culture/gender bias, symptom overlap
Reliability
↳ The same person, showing the same symptoms, may get a diagnosis of SZ from one
//..clinician but not from another
Diagnostic reliability - diagnosis of SZ must be repeatable, conclusions must be the same
- At 2 different points in time (test-retest)
- By different clinicians (inter-rater)
Reliability is an issue as…There is no one agreed system of classification
● DSM-V: Diagnostic and statistical manual of mental disorders
● ICD-10: International Classification of Mental Disorders
Difference between DSM-V and ICD-10 (diagnostic manuals):
● DSM requires at least 1 positive symptom, ICD positive symptoms are not required
● DSM requires symptoms to be present for 6 months, ICD present for 1 month
● ICD is used in most parts of the world, DSM is used in USA
This creates an issue:
● As there’s not one agreed system of classification
● Clinicians use different classifications depending on if they're using DSM or ICD
● Means the same person receives a different diagnosis depending on criteria used
Research evidence: Cooper (1972) → US/UK diagnostic project:
● 250 p’s were considered by American AND British psychiatrists separately
● 163 diagnosed as SZ by the American psychiatrists (using DSM)
● 85 diagnosed as SZ by the British psychiatrists (using ICD)
● Suggested American psychiatrists were almost 2x as likely to diagnose SZ
● (Kendell,1971) - USA psychiatrists diagnosing 4x the rate of British psychiatrists
Conclusion
● ‘The difference in diagnostic rates wasn’t due to different incident rates (not that
more in the USA have SZ) because...... They used the SAME patients
● Therefore it must be due to the differences in the definition of SZ
● The US was using a broader definition of SZ compared to the UK
, Implications of research
● Implications for validity of diagnosis, whether they received the correct diagnosis
● Research suggests people are being diagnosed who shouldn’t
● Others are NOT being diagnosed when they should
● Implications for treatment - people may be receiving inappropriate treatment OR
not receiving any treatment at all!
How can we overcome the problem (increase reliability)
● Have one classification of SZ
● Unlikely to happen(ICD / DSM will remain separate) but the ICD and DSM have
become more similar than they used to be
● There is still an issue of clinician subjectivity
Lack of inter-rater reliability
● Little evidence the DSM is used with high reliability by mental health clinicians
● Whaley (2001) found inter-rater reliability correlations as low as 0.11
● Suggests as psychiatric diagnosis lacks some of the more objective measures, it
inevitably faces additional challenges with inter-rater reliability
Bizarre beliefs
● For diagnosis of SZ, only 1 characteristic is required ‘if delusions are bizarre’
● Bizarre → delusions are implausible / not understandable to same-culture peers
and don’t derive from ordinary life experiences
● This creates problems for reliability of diagnosis (difference in opinions on bizarre)
● 50 (US) senior psychiatrists had to differentiate between ‘bizarre’ and ‘non-bizarre’
delusions (Mojatabi and Nicholson, 1995)
● They produced inter-rater reliability correlations of only around 0.40
● Their research concluded the central diagnostic criterion lacks reliability for it to be
reliable method of distinguishing between SZ and non-SZ patients
The fact that the diagnosis is unreliable means there is an issue of validity...
Notes
Paper 3 - Section C
,Schizophrenia
Classification and diagnosis
- Mental disorders are organised in categories so they can be accurately identified
- SZ is classified as a psychotic disorder (others are mood, eating and anxiety…)
- Psychosis is broadly defined as a loss of contact with reality
- Clinicians match p’s symptoms to clinical characteristics in the classification system
- This produces a diagnosis
Classification of SZ → Clinical characteristics
Criterion A: 2 (or more) of the following (only 1 if delusions are bizarre / auditory
hallucinations) each present for a significant portion of time during a 1 month period:
Delusions of persecution: belief people are plotting against them, often
Misinterpretation trying to kill them e.g. milkman is trying to kill them
of sensory info
of grandeur: belief they’re someone famous / important e.g.
believing they are Jesus
Hallucinations visual: seeing things that are not there
Sensory experience
auditory: hearing voices
in absence of real
stimulus tactile: feeling like something’s touching you/ skin when it’s not
Disorganised ‘word salads’: jumbled, ungrammatical speech e.g. ‘colourless
speech green ideas sleep furiously’
neologisms: creating new words e.g. ‘norks are going to get me’
Disorganised violating social norms: e.g inappropriately dressed (the ‘bag lady’
Behaviour image) / inappropriate gestures e.g. repetitive gestures at people
Catatonic rocking / maintaining uncomfortable positions for a long time
Behaviour fixed glare
Negative speech poverty (alogia): lack of additional, unprompted speech
symptoms
Avolition (aka apathy): loss of motivation / goal oriented behaviour
and results in lowered activity levels
flat affect: (affective flattening) failure to show emotional
response when expected e.g. no response to family member dying
Criterion B One (or more) major areas of functioning e.g as work, self-care,
Social / Occupational interpersonal relations are markedly below normal levels
Dysfunction
Criterion C Continuous signs of disturbance last at least 6 months
Duration 6 month period must include at least 1 month of symptoms that
meet Criterion A
POSITIVE SYMPTOMS → ADDITIONAL experiences / symptoms beyond what is normal
NEGATIVE SYMPTOMS → LOSS of usual abilities and experiences
,Reliability and validity in diagnosis and classification of schizophrenia
Key issues: reliability, validity, labelling, commodity, culture/gender bias, symptom overlap
Reliability
↳ The same person, showing the same symptoms, may get a diagnosis of SZ from one
//..clinician but not from another
Diagnostic reliability - diagnosis of SZ must be repeatable, conclusions must be the same
- At 2 different points in time (test-retest)
- By different clinicians (inter-rater)
Reliability is an issue as…There is no one agreed system of classification
● DSM-V: Diagnostic and statistical manual of mental disorders
● ICD-10: International Classification of Mental Disorders
Difference between DSM-V and ICD-10 (diagnostic manuals):
● DSM requires at least 1 positive symptom, ICD positive symptoms are not required
● DSM requires symptoms to be present for 6 months, ICD present for 1 month
● ICD is used in most parts of the world, DSM is used in USA
This creates an issue:
● As there’s not one agreed system of classification
● Clinicians use different classifications depending on if they're using DSM or ICD
● Means the same person receives a different diagnosis depending on criteria used
Research evidence: Cooper (1972) → US/UK diagnostic project:
● 250 p’s were considered by American AND British psychiatrists separately
● 163 diagnosed as SZ by the American psychiatrists (using DSM)
● 85 diagnosed as SZ by the British psychiatrists (using ICD)
● Suggested American psychiatrists were almost 2x as likely to diagnose SZ
● (Kendell,1971) - USA psychiatrists diagnosing 4x the rate of British psychiatrists
Conclusion
● ‘The difference in diagnostic rates wasn’t due to different incident rates (not that
more in the USA have SZ) because...... They used the SAME patients
● Therefore it must be due to the differences in the definition of SZ
● The US was using a broader definition of SZ compared to the UK
, Implications of research
● Implications for validity of diagnosis, whether they received the correct diagnosis
● Research suggests people are being diagnosed who shouldn’t
● Others are NOT being diagnosed when they should
● Implications for treatment - people may be receiving inappropriate treatment OR
not receiving any treatment at all!
How can we overcome the problem (increase reliability)
● Have one classification of SZ
● Unlikely to happen(ICD / DSM will remain separate) but the ICD and DSM have
become more similar than they used to be
● There is still an issue of clinician subjectivity
Lack of inter-rater reliability
● Little evidence the DSM is used with high reliability by mental health clinicians
● Whaley (2001) found inter-rater reliability correlations as low as 0.11
● Suggests as psychiatric diagnosis lacks some of the more objective measures, it
inevitably faces additional challenges with inter-rater reliability
Bizarre beliefs
● For diagnosis of SZ, only 1 characteristic is required ‘if delusions are bizarre’
● Bizarre → delusions are implausible / not understandable to same-culture peers
and don’t derive from ordinary life experiences
● This creates problems for reliability of diagnosis (difference in opinions on bizarre)
● 50 (US) senior psychiatrists had to differentiate between ‘bizarre’ and ‘non-bizarre’
delusions (Mojatabi and Nicholson, 1995)
● They produced inter-rater reliability correlations of only around 0.40
● Their research concluded the central diagnostic criterion lacks reliability for it to be
reliable method of distinguishing between SZ and non-SZ patients
The fact that the diagnosis is unreliable means there is an issue of validity...
