classification and diagnosis

• Schizophrenia


  Schizophrenia is a psychological condition characterised by a loss of contact with reality
• Positive symptoms


  Hallucinations-perceptions that aren't based in reality, or distorted perceptions of reality

  
  

  Delusions- beliefs that aren't based in reality
• negative symptoms


  Speech poverty- a reduction in the quality and amount of speech

  
  

  Avolition- a lack of desire and motivation for anything
• Two main systems for diagnosing schizophrenia

  DSM-5 requires at least one positive symptom, but ICD-10 can diagnose on negative symptoms alone
• Diagnosis and reliability

  If multiple different doctors diagnose the same person as schizophrenic based on the same symptoms, then their diagnosis is reliable

  
  

  Beck et al (1962) - psychiatrists' own assessment - 54% concordance rate

  
  

  Soderberg et al (2005) - DSM - 81% concordance rate

  
  

  Jakobsen et al (2005) - ICD - 98% concordance rate
• AO3-Improvements in inter observer reliability

  Although research is conflicting, more recent studies of schizophrenia diagnosis generally find higher concordance rates among psychiatrists compared to older studies. This suggests that diagnosis of schizophrenia has become more reliable over time
• AO3-low reliability between diagnostic methods

  Cheniaux et al (2009) found the same observer would often diagnose schizophrenia differently depending on which manual they used (DSM vs ICD). In general, the DSM classification is considered more reliable as the description of symptoms are more specific
• AO3-co morbidity

  People with schizophrenia often suffer from psychological disorders in addition to schizophrenia, which confuses diagnosis e.g. people with schizophrenia often suffer from depression as well.
• Diagnosis and validity

  Validity refers to how accurately schizophrenia is diagnosed e.g. if doctors often diagnose patients with autism as having schizophrenia, then their diagnosis is not valid.
• Rosenhan (1973)-being sane in insane places


  8 healthy volunteers presented themselves to various psychiatric hospitals claiming to hear voices

  
  

  All 8 volunteers were successfully admitted to the hospitals and diagnosed with schizophrenia. Doctors took between 7-52 days to release each 'patient'

  
  

  In a later experiment, doctors were falsely told that healthy patients would attempt to admit themselves, which led the doctors to turn genuine schizophrenic patients away because they thought they were actors

  
  

  The doctors did not have valid methods for diagnosing schizophrenia
• AO3-Improvements in validity

  although Rosenhan (1973) casts doubt on the validity of schizophrenia diagnosis, more recent studies suggest schizophrenia diagnosis has become more accurate e.g. Mason et al (1997) found that improvements to diagnostic manuals (DSM and ICD) over time led to more accurate diagnosis of schizophrenia
• AO3-Symptom overlap

  schizophrenia shares symptoms with disorders such as depression and autism e.g. people with schizophrenia and people with autism often suffer with speech poverty. This overlap of symptoms may reduce the validity of schizophrenic diagnosis because an evaluator may incorrectly attribute these symptoms to a different disorder
• AO3-Gender differences

  a meta-analysis from Aleman et al (2003) found men were 42% more likely to suffer from schizophrenia than women. However, Cotton et al (2009) suggests that the better interpersonal functioning of women may cause doctors to miss schizophrenia diagnosis in women, suggesting possible gender bias in schizophrenia diagnosis
• AO3-Cultural differences

  several studies have found ethnic minorities living in Britain are diagnosed with schizophrenia at higher rates than white people. However, rates of schizophrenia diagnosis among Afro-Caribbean people living in the Caribbean are roughly the same as white people in Britain. This suggests either that environmental stressors in Britain are causing increased rates of schizophrenia among people of Afro-Caribbean descent, or that Afro-Caribbean people are being invalidly diagnosed with schizophrenia