Schizophrenia - Features of Schizophrenia Flashcards
How is schizophrenia classified?
There is no single defining characteristic. Schizophrenia is a collection of seemingly unrelated symptoms. There are many misconceptions and exaggerations surrounding the nature of schizophrenia.
How do the DSM-5 and ICD-10 differ?
DSM-5: one positive symptom must be present (delusions, hallucinations or speech disorganization).
ICD-10: Two or more negative symptoms are sufficient for diagnosis (e.g. avolition and speech poverty).
What are positive symptoms of schizophrenia?
Additional experiences beyond those of ordinary existence. They are an excess or distortion of normal functioning.
- hallucinations
- delusions
What are hallucinations?
Sensory experiences that have no basis in reality or distorted perceptions of real things. Experienced in relation to any sense.
What are delusions?
Beliefs that have no basis in reality - make a person with schizophrenia behave in ways that make sense to them but are bizarre to others.
What are negative symptoms of schizophrenia?
Loss of usual abilities and experiences. They are a loss or reduction in normal functioning.
- avolition
- speech poverty
What is avolition?
Severe loss of motivation to carry out everyday tasks (e.g. work, hobbies, personal care). Results in lowered activity levels and unwillingness to carry out goal-directed behaviours.
What is speech poverty?
A reduction in the amount and quality of speech. May include a delay in verbal responses during conversation. DSM emphasises speech disorganisation and incoherence.
What are the key issues in the diagnosis of schizophrenia?
- Reliability: the extent to which the diagnosis of schizophrenia is consistent.
- Validity: the extent to which the diagnosis and classification techniques measure what they are designed to measure, in this case to measure schizophrenia.
- Co-morbidity: occurrence of two illnesses together which confuses diagnosis and treatment.
- Symptom overlap: when two or more conditions share symptoms, questioning the validity of the classification.
What are the weaknesses of the diagnosis of schizophrenia?
- low reliability
- poor validity
- co-morbidity
- gender bias
- cultural bias
How does the diagnosis of schizophrenia have low reliability?
Cheniaux et al. (2009) had two psychiatrists independently diagnose 100 patients using both DSM and ICD criteria.
Inter-rater reliability was poor. One psychiatrist diagnosed 26 with schizophrenia using DSM and 44 using ICD. Second psychiatrist diagnosed 13 with DSM and 24 with ICD.
This inconsistency between mental health professionals and the different classification systems is a limitation of the diagnosis.
How does the diagnosis of schizophrenia have poor validity?
A standard way to assess validity of a diagnosis is criterion validity - do different assessment systems arrive at the same diagnosis for the same patient?
Cheniaux et al.’s study shows that schizophrenia is much more likely to be diagnosed using ICD than DSM.
This suggests that schizophrenia is either over-diagnosed in ICD or under-diagnosed in DSM. This is poor validity and a weakness of the diagnosis.
Why is co-morbidity a weakness of the diagnosis of schizophrenia?
Co-morbidity is when two or more conditions occur together. If conditions occur together, a lot of the time it might call into question whether they are actually a single condition.
Buckley et al. (2009) concluded that around half of patients with a diagnosis of schizophrenia also have a diagnosis of depression (50%) or substance abuse (47%).
In terms of classification, if very severe depression looks like schizophrenia and vice versa, it may be they are a single condition. This confusing picture is a limitation.
How is there gender bias in the diagnosis of schizophrenia?
Longenecker et al. (2010) reviewed studies of the prevalence of schizophrenia and concluded that since the 1980s, men have been diagnosed more often than women.
Cotton et al. (2009) found female patients typically function better than men. This may explain why some women escape diagnosis because their better interpersonal functioning may bias practitioners to under-diagnose schizophrenia.
This is a problem because men and women with similar symptoms may experience different diagnoses.
How is there cultural bias in the diagnosis of schizophrenia?
African-Americans and English people of African origin are much more likely to be diagnosed with schizophrenia in the UK. Rates in the West Indies and Africa are not high, so this is not due to genetic vulnerability.
Higher diagnosis rates in the UK may be because some behaviours classed as positive symptoms of schizophrenia are ‘normal’ in African cultures (e.g. hearing voices as part of ancestor communication).
This highlights an issue in the validity of diagnosis because it suggests that individuals from some cultural backgrounds are more likely to be diagnosed than others due to bias.
