*NEW* Schizophrenia ; Reliability and validity in diagnosis and classification Flashcards
Define schizophrenia
A type of psychosis characterised by a profound disruption of cognition and emotion. (Affects 1% of the population at some point in their lifetime)
What are positive symptoms
symptoms which add to the sufferers’ experience such as hallucinations or delusions
What are hallucinations
unreal perceptions of the environment that are usually auditory or visual. Can also be olfactory (smells) and tactile (feeling)
What are delusions
bizarre beliefs that seem real to the person with schizophrenia but aren’t real . E.g paranoia, delusions of grandeur.
What is disorganised speech
the result of abnormal thought processes, where the individual as problems organising their thoughts and this shows up in their speech
What is catatonic behaviour
includes the inability or motivation to initiate a task or to complete it once started , which leads to difficulties in everyday life and can result in decreased interest in personal hygiene.
What are negative symptoms
symptoms which take away from the sufferers’ experience such as avolition or speech poverty
What is speech poverty?
the lessening of speech fluency and productivity, this is thought to reflect slowing or blocked thoughts. May produce fewer words in a given time on a task of verbal fluency, fewer clauses
What is avolition?
a reduction of interests and desires as well as an inability to initiate and persist in goal directed behaviour. A reduction in self-initiated involvement in activities that are available to the patient.
What is reliability of diagnosis ?
The consistency of a classificatory system such as DSM to assess schizophrenia
Explain cultural differences in diagnosis?
People of afro-caribbean heritage are 7 times more likely to be diagnosed with schizophrenia in the uk than a white person. This is because there is culture bias in the way people are diagnosed, it is imposed because in the uk the diagnostic tools we use are the same for everyone. This means that positive symptoms of SZ such as religious hallucinations (speaking to God or being visited by an angel) which would be celebrated in afro-caribbean culture is classified as a symptom of SZ in the uk.
Name two researchers that investigated culture differences in diagnosis
Copeland, Luhrmann
What did Copeland do and find?
gave 134 US and 194 British psychiatrists a description of a patient . 69% of US psychiatrists diagnosed schizophrenia, but only 2 % of the British ones gave the same diagnosis.
What did Luhrmann do and find?
Interviewed 60 adults diagnosed with schizophrenia - 20 each in Ghana, India and the US - each were asked about the voices they heard in their head. Found that African and Indian participants reported positive experiences with the voices they heard, they said that they were playful and offered advice but not one of the American’s did. The US participants were more likely to report the voices as violent and hateful. Luhrmann suggests that the “ harsh, violent voices so common in the West may not be an inevitable feature of Schizophrenia.’
Define validity of schizophrenia diagnosis
Refers to the extent that a diagnosis represents something that is real and distinct from other disorders and the extent that a classification system such as DSM measures what it claims to measure.
Explain gender bias in diagnosis
Occurs when accuracy of diagnosis is dependent on the gender of the individual.
The accuracy of diagnostic judgement can vary due to a number of reasons: there are gender biassed diagnostic criteria or clinicians basing their judgments on stereotypical beliefs held about their gender.
Who investigated gender bias in diagnosis? What did they find?
Broverman found that clinicians in the US equated mentally healthy ‘adult’ behaviour with mentally healthy ‘male’ behaviour . As a result, there was a tendency for women to be perceived as less mentally healthy
What is comorbidity?
When a condition often occurs alongside other conditions. For example, depression and anxiety are often diagnosed alongside Schizophrenia
Who investigated comorbidity in diagnosis? What did they find?
Buckley et al estimate that co-morbid depression occurs in 50% of SZ patients and 47% of participants also have a lifetime diagnosis of comorbid substance abuse.
What is symptom overlap?
When more than one condition share symptoms such as avolition is common in depression and schizophrenia.
Who investigated symptom overlap in diagnosis? What did they find?
Ellason and Ross pointed out that people with DID actually have more schizophrenic symptoms than people diagnosed with schizophrenia
What diagnostic tool is used commonly in the US?
DSM - V
What diagnostic tool is most commonly used in Europe?
ICD-10
Explain the lack of inter-rater reliability with schizophrenia diagnosis using DSM-V
There is still little evidence that DSM is routinely used with high reliability. Whaley found inter-rater reliability correlations in diagnosis of sz as low as 0.11 .
Explain Rosenhan’s famous study and its findings
‘Normal’ people presented themselves to psychiatric hospitals in the US, claiming they heard an unfamiliar voice saying the words ‘empty,’ ‘hollow’, ‘thud’ . They were all diagnosed with SZ and admitted. Throughout their stay, none of the staff recognised that they were ‘normal’. It took ages for the participants to be released from the hospital despite not having any mental health issues.
Explain the unreliability of symptoms in SZ
For a diagnosis of sz, only one of the characteristic symptoms is required ‘if delusions are bizarre’ . However this creates problems with reliability. When 50 senior clinicians in the US were asked to differentiate between ‘bizarre’ and ‘non-bizarre’ delusions , they produced an inter-rater reliability correlation of only around 0.40. Even this central diagnostic requirement lacks sufficient reliability .
Who provided research support for gender bias in diagnosis? What was their procedure and what did they find?
Loring and Powell randomly selected 290 male and female psychiatrists to read two case vignettes of patient’s behaviour. They were then asked to offer their judgement on the individuals using standard diagnostic criteria
- When patients were describes as ‘males’ or no information given about their gender = 56% gave a diagnosis
- When the patients were described as ‘female’, only 20% were given a diagnosis
- Gender bias was not as evident among the female psychiatrists, suggesting that diagnosis is influenced not only by gender of the patient but by the gender of the clinician
Explain why sz diagnosis lacks predictive validity
There is no evidence to suggest that people diagnosed with SZ share the same outcomes . The prognosis varies
- 20% recovering their previous level of functioning
- 10% achieving long lasting improvement
- 30% showing some improvement with intermittent relapse
Some people never recover from the disorder but some do. Harrison found that gender, social skills, academic achievement and family tolerance of sz behaviour does influence the patient’s outcome.
