A03

• Reliability

  1. Lack of inter-rater reliability
  2. Cultural differences
• Validity

  1. Gender bias
  2. Symptom overlap
  3. Co-morbidity
• Reliability = lack of inter-rater reliability

  • Schizophrenia has been shown to have poor inter-rater reliability
  • Whaley (2001) found inter-rater reliability correlations as low as 0.11
  • Rosenhan (1973) - ’normal‘ people presented themselves to psychiatric hospitals in the US claiming they heard unfamiliar voices in their head saying the words empty, hollow and thud
  • They were all diagnosed as having schizophrenia and admitted
  • Throughout their stay none of the staff recognised that they were not actually displaying symptoms of schizophrenia
• Reliability = cultural differences

  • Research suggests there is a significant variation between countries when it comes to diagnosing schizophrenia
  • Copeland (1971) gave US and British psychiatrists a description of a patient
  • 69% of the US psychiatrists diagnosed schizophrenia, but only 2% of the British ones gave the same diagnosis
  • Hearing voices is more acceptable in African cultures due to cultural beliefs in communication with ancestors
  • A psychiatrist from a different culture is more likely to see these experiences as irrational = more likely to be diagnosed with schizophrenia
• Validity = gender bias

  • Said to occur when accuracy of diagnosis is dependent on the gender of an individual
  • Found that males are more likely to be diagnosed than females as they appear to function better e.g. more likely to work and have good family relationships
  • Loring and Powell (1988) selected 290 male and female psychiatrists to read two case studies of patients’ behaviour and asked to offer their judgement
  • When patients described as ’males’, 56% of psychiatrists gave a diagnosis of schizophrenia compared to 20% when described as ‘females’
• Validity = symptom overlap

  • There is overlap between the symptoms of schizophrenia and other conditions
  • Ellason et al. (1995) claimed that Dissociative Identity Disorder has more schizophrenic symptoms than people diagnosed with schizophrenia
  • Both schizophrenia and bipolar disorder involve positive symptoms like delusions and negative symptoms like avolition
  • Under ICD a patient might be diagnosed as a schizophrenic but many of the same patients would receive a diagnosis of bipolar disorder according to DSM criteria
• Validity = co-morbidity

  • Co-morbidities are common among patients with schizophrenia and this brings into question the extent to which they are separate disorders and not just a single condition
  • Buckley et al. (2009) - around half of patients with a diagnosis of schizophrenia also have a diagnosis of depression or substance abuse, or OCD
  • In terms of classification, it may be that, if very severe depression looks a lot like schizophrenia and vice versa, then they might be better seen as a single condition