No single defining characteristic: collection of seemingly unrelated symptoms, many misconceptions+exagerations surrouding the nature of schizophrenia.
DSM-5 and ICD-10 differ:
DSM 5: one + symptom must be present (delusions, hallucinations).
ICD-10: two or more - symptoms=sufficient for diagnosis (avolition, speech poverty).
Symptoms:
+ symptoms= additional experiences beyond those that already exist:
Hallucinations: sensory experiences that have distorted perceptions of real things, e.g. seeing people who aren't there.
Delusions: Beliefs that no basis in reality- person with schizophrenia behaves in a way that is normal to them, but bizzare to others, e.g. being victim of a conspiracy.
- symptoms= loss of usual abilities+experiences
Avolition: severe loss of motivation to carry out everyday tasks (work, personal hygiene), unwillingness to carry out goal-directed behaviour.
Speech poverty: reduction in amount+quality of speech- delay in verbal responses during conversation.
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Issues in diagnosis (AO1)
Key issues:
Reliability: extent to which the diagnosis of schizophrenia is constistant.
Validity: extent to which diagnosis+classification techniques measure what they are designed to measure.
Co-morbidity: occurence of two illnesses together which confuse diagnosis+treatment.
Symptom overlap: when two or more conditions share symptoms, questioning validity of the classification.
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Evaluation: limitations (AO3)
Diagnosis of schizophrenia has low reliability:
Cheniaux et al. (2009) had two psychiatrists diagnose 100 pp's using DSM and ICD criteria.
Inter-rater reliability was poor; one psychiatrist diagnosed 70 with schizophrenia using both criteria, the other diagnosed 37.
Inconsistency between mental health professionals and different classification systems is a limitation of the diagnosis because it supports the theory that the consistency of the diagnosis of schizophrenia is low.
Diagnosis of schizophrenia has low validity:
Standard way to assess validity of diagnosis is criterion validity, do different assessment systems meet the same criteria, thus arriving at the same diagnosis?
Cheniaux et al.'s study shows that schizophrenia is much more likely to be diagnosed using ICD than DSM.
Suggest that schizophrenia is either over-diagnosed in ICD or under-diagnosed in DSM, which highlights the low validity of the diagnosis.
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Evaluation: limitations (AO3)
Gender bias in the diagnosis of schizophrenia:
Longenecker et al. (2010) reviewed studies that showed that since the 1980s men have been diagnosed more often than women.
Cotten et al. (2009) found female patients function better than men. Could explain why some women escape diagnosis because their stronger interpersonal functioning may bias practioners to under-diagnose schizophrenia.
Problem because men and women with similar symptoms may experience differing diagnoses. Consequently, gender bias decreases the reliability of the diagnosis because men are being over-diagnosed and women are being under diagnosed.
Cultural bias in the diagnosis of schizophrenia:
African-Americans are much more likely to be diagnosed with the illness in the UK. Whereas, rates of diagnosis are much lower in the West Indies and Africa.
Higher diagnosis rates in the UK could be due to some behaviour that is classed as a postive symptom is normal in African cultures, e.g. hearing voices as part of ancestor communication.
Highlights the issue of validity of diagnosis because it suggests that individuals from some cultural backgrounds are more likely to be diagnosed than others to cultural bias.
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