1. Diagnosis and classification

• What is schizophrenia?

  • A psychotic disorder present in 1% of the worlds population
  • More common in men and lower socio-economic groups
• Diagnosis and classification

  • Diagnosis - identifying positive and negative symptoms according to the medical approach
  • Classification - organising clusters of symptoms into categories based on which symptoms frequently cluster together
  • WHO ICD 10 - two or more negative symptoms for a diagnosis
  • APA DSM 5 - one positive symptom
  • The two models differ slightly
• Positive symptoms

  • Hallucinations - unusual sensory experiences such as voices or facial expressions that aren't really there. They can be experienced in relation to any sense
  • Delusions - paranoia or irrational beliefs. Common delusions involve important historical or political figures and may involve an individual believe they are being persecuted or being under external control
• Negative symptoms

  • Speech poverty - changes in patterns of speech and is negative as it emphasises the reduction in the amount and quality of speech. Sometimes accompanied by a delay in verbal response. Classified as a positive symptom in DSM-5
  • Avolition - sometimes called 'apathy' and can be described as finding it difficult to begin or keep up with goal directed activity. Sharply reduced motivation and Nancy Andreasen identified three signs of avolition, poor hygiene and grooming, lack of persistence in work or education and lack of energy
• AO3 - Strength of reliability

  • Reliability means consistency and a psychiatric diagnosis is said to be reliable when different clinicians reach the same diagnosis for the same individual (inter-rater reliability)
  • Prior to DSM-5 reliability for Sz diagnosis was less reliable but has improved
  • Flavia Osorio et al. report excellent reliability for diagnosis in 180 individuals using DSM 5
  • Interviewers reached inter-rater reliability of +9.7 and test retest of +9.2
• AO3 - Limitation of low validity

  • Validity concerns whether we are assessing what we are intending to assess
  • One way to assess validity of a psychiatric diagnosis is criterion validity
  • Cheniaux et al. had two psychiatrists independently assess the same 100 clients using ICD 10 and DSM 5 criteria and found that ICD 10 diagnosed 68 and DSM 5 39
  • Not an accurate measurement and are subjective
• AO3 - Limitation of culture bias

  • Some symptoms such as hallucinations like hearing voices are much more common in certain cultures and viewed as the norm
  • People in Haiti view hearing voices as messages from their ancestors
  • This leads to different diagnosis manuals being created such as DSM and ICD which are characterised by different symptoms
  • Different cultural backgrounds hold different views on what schizophrenia looks like meaning that classification may be subjective
• AO3 - Limitation of symptoms overlapping

  • Both Sz and bipolar disorder involve positive symptoms such as delusions and negative symptoms such as avolition
  • In terms of classification, this suggests that both Sz and bipolar may not be separate disorders but variations of the same one
  • In terms of diagnosis, it is hard to distinguish the two
  • Classification and diagnosis are flawed