classification & diagnosis

• negative symptoms of SZ

  speech poverty, avolition
• positive symptoms of sz


  delusions, hallucinations
• clasification & diagnosis strength

  -good reliability

  -prior to DSM, reliability of diagnosis has improved in test-retest reliability

  • Osorio (2019) reported excellent reliability in 180 people using DSM-5
  • shows we can be reasonably sure the diagnosis is consistently applied
• diagnosis & classification limitation

  low validity

  • Cheniaux (2009) had 2 psychiatrists asses the same 100 patients using DSM-5 and ICD-10 and found that 68 were diagnosed under ICD and 39 under DSM
  • suggests SZ is over or under diagnosed and criterion validity is low
• gender bias- weakness

  • since 1980s, men are more commonly diagnosed-> Fischer
  • this is because due to genetics, women are less vulnerable. however, women are under diagnosed due to getting support
  • this suggests women aren't receiving treatment they need
• symptom overlap-weakness

  • overlapping symptoms with other conditions e.g. bipolar also has pos/neg symptoms which could suggest they're not 2 different conditions but are variations of 1
  • means diagnosis is flawed as sz is hard to distinguish (low validity)
• different systems for classifying sz

  • ICD-10, 2 or more negative symptoms. world health organisation classification of disease
  • DSM-5, 1 positive symptom. American psychiatric manual