Diagnosis and Classification Flashcards
what aspects of functioning are affected by schizophrenia
a person’s: language, thought, perception and sense of self
at what age is SZ typically diagnosed
between the ages 15-35
who is more commonly affected
males, people in cities, those in the working class
how prevalent is SZ
- ranks among the top 10 causes of disabilty worldwide
- affects about 1% of the population at some point in their life.
definition of a positive symptom of SZ
atypical symptoms experienced in addition to normal experiences
- e.g. hallucinations
definition of a negative symptom of SZ
atypical symptoms that represent a loss to normal experiences
- e.g. speech poverty
what is the difference between positive and negative symptoms of SZ
positive = in addition to normal experiences
negative = a loss to normal experiences
what are the positive symptoms of SZ
- hallucinations
- delusions
hallucinations
- unusual sensory perceptual experiences
- may or may not be related to events in the environment
- voices heard talking or commenting on the sufferer (often criticism)
- can be experienced in relation to any sense
delusions
- irrational, bizarre, beliefs that seem real to the person with SZ
- can take a range of forms: delusions of grandeur, paranoid delusions, delusions of reference
delusions of grandeur
e.g. involve being an important historical, political, or religious figure such as Jesus or Napoleon
paranoid/persecutory delusions
being persecuted, perhaps by government or aliens or of having superpowers
delusions of reference
may believe they are under external control, or that events in the environment are directly related to them
- e.g. personal messages through the TV
what are the negative symptoms of SZ
- avolition
- speech poverty (Alogia)
avolition
- sometimes called apathy
- finding it difficult to begin or to keep up with goal-directed activity
- Andreason (1982) identified 3 signs of avolition
Andreason’s (1982) 3 signs of avolition
- poor hygiene and grooming
- lack of persistence in work or education
- lack of energy
speech poverty (Alogia)
- lessening of speech fluency and productivity reflecting slow or blocked thoughts
- sometimes accompanied by a delay in the sufferer’s verbal responses during conversation
- DSM-5 system places emphasis on speech disorganisation
- ICD-10 says speech poverty is a negative symptom
how is SZ diagnosed
diagnosis is done through interveiw and observation and is therefore subjective
- e.g. blood tests, x-rays
why is diagnosing SZ problematic
- it does not have 1 defining characteristic
- no reliable diagnostic biomarkers of differential diagnosis or prognosis
- in addition ICD-11 and DSM-5 differ in their diagnosis
what is a classification system
a system that collects the symptoms of a disorder
how are classification systems used in psychiatry
used to diagnose the disorder
what are the 2 major systems for the classification of a mental disorder
- World Health Organisation’s International Classification of Disease edition 10 (ICD-10)
- the American Psychiatrists Association’s Diagnostic and Statistical Manual edition 5 (DSM-5)
which symptoms are required for an ICD-10 based diagnosis of SZ and for how long
- 2 or more negative symptoms
- 1 month
the ICD-10 also recognise a range of subtypes of SZ which are:
- paranoid
- hebrephrenic
- catatonic
are positive symptoms required for ICD-10
no
which symptoms are required for a diagnosis of SZ in the DSM-5 and for how long
2 or more of the following for1 month (or longer) at least 1 of them MUST be positive
- delusions
- hallucinations
- disorganised speech
- grossly disorganised or catatonic behaviour
- negative symptoms such as diminished emotional expression
additional criteria for DSM-5 diagnosis
- impairment in one of the major areas of functioning for a significant amount of time since the onset of disturbance
- some signs of the disorder must last for a continuous period at least 6 months
- schizoaffective disorder and bipolar or depressive disorder with psychotic features have been ruled out
what are the mai differences between DSM-5 and ICD-10
DSM = signs present for 6 months and one symptom MUST be positive
ICD = signs present for 1 month only and 2 negatives are enough
what is the impact of the differences in the classification systems
poses challenges with reliability and validity
AO3 - what is reliability
refers to the consistency of the diagnostic instrument to assess the severity of the SZ symptoms
AO3 - what is validity
refers to the extent that a diagnosis represents something that is real and distinct from other disorders and the extent that a classification system measures what it claims to measure
AO3 - how do the terms reliability and validity apply to SZ
R & V are linked. a diagnosis cannot be valid if it is not reliable
AO3 - what issues are there with the reliability of the diagnosis of SZ
- extent to which a psychiatrist can agree on the same diagnosis when independently assessing patients (inter-rater reliability)
- for a classification system to be reliable, the same diagnosis should be made each time. Therefore different psychiatrists should reach the same decision when assessing a patient
- same diagnostic tool should also assess patient with the same diagnosis over a period of time (test-retest reliability)
AO3 - who and when did a study that investigated the reliability of diagnosis in SZ and what did they do
- Cheniaux et al
- 2009
- had 2 psychiatrists independently diagnose 100 patients using the ICD and DSM criteria
what were Cheniaux et al 2009 findings
- 1st diagnosed 26 with DSM and 44 with ICD
-2nd diagnosed 13 with DSM and 24 with ICD
AO3 - what does Cheniaux et al’s findings present
- an issue with inter-rater reliability
- shows diagnosis os SZ is not reliable because diagnosis and treatment depends upon the psychiatrist that you see rather than the symptoms you present
how is validity assessed in diagnosis
a standard way to assess validity of diagnosis is using criterion validity
what is criterion validity
evaluates how accurately a test measures the outcome it was designed to measure
AO3 - PEEL = explain how Rosenhan’s1973 study questions the validity of psychiatric diagnoses
p - situational factors have a diagnosis of SZ
e - 8 confederates acted as pseudopatients, going to 12 different hospitals
- complained of hearing voices prior to admission, then stopped pretending to have symptoms once admitted
- staff diagnosed 11/12 with SZ and 1 with manic depression
- average hospital stay = 19 days
- 35 patients detected sanity in pseudopatients
e - psychiatric staff cannot always distinguish sanity from insanity.
l - this suggests the validity of psychiatric diagnoses was low and DSM was flawed
AO3 - what is predicitve validity and how does it relate to SZ diagnosis
- people with SZ rarely share the same symptoms or outcomes
- the prognosis for patients suffering with SZ varies wih about 20% recovering their previous level of functioning, 10% significant improvement and 30% come improvement
- a diagnosis therefore has little predictive validity. gender and psycho-social factors do appear to influence outcome
AO3 - How do issues with co-morbidity undermine the validity of SZ diagnoses
- co-morbidity refers to the occurrence of 2 illnesses together
- Buckley et al (2009) concluded that around half the patients with a diagnosis of SZ also have a diagnosis of depression (50%) or substance abuse (47%)
- post traumatic stress occurred in 29% of SZ cases and OCD in 23%
AO3 - how do issuses with regard to symptom and genetic overlap undermine diagnostic validity
- symptom overlap is when 2 or more conditions share the same symptoms
- Litenstein 2009 found that there are shared genes which cause bipolar and SZ. they overlap so much SZ might not actually be a distinct disease from bipolar. they have many shared symptoms including psychosis
AO3 - how do issues with regard to gender bias undermine diagnostic validity
- longenecker et al. (2010) reviewed literature and found since the 1980’s men are more likely to be diagnosed with SZ
- cootton et al (2009) suggest this is because women are better at coping - i.e. “more highly functioning”
AO3 - How do issues with regard to culture bias undermine diagnostic validity, and indicates a cultural bias?
research suggest there is a significant variation between countries when it comes to diagnosing SZ
AO3 - How do issues with regard to culture bias undermine diagnostic validity, and indicates a cultural bias?
Harrison et al. 1971
- suggested that those of West Indian origin were over diagnosed with SZ
- specifically by white doctors in Bristol
- due to ethnic background
AO3 - How do issues with regard to culture bias undermine diagnostic validity, and indicates a cultural bias?
Escobar 2012
- argues that psychiatrists may over interpret symptoms and distrust the honesty of black people during diagnosis
AO3 - How do issues with regard to culture bias undermine diagnostic validity, and indicates a cultural bias?
Copeland et al 1971
- gave a description of an american patient to 134 US and 194 British psychiatrists
- 69% of US psychiatrists diagnosed SZ
- 2% of British psychiatrists diagnosed SZ
