introduction to schizophrenia

• schizophrenia - 


  severe mental disorder where contact with reality and insight are impaired
• diagnosis and classification -

  • to diagnose a specific disorder, need to distinguish one disorder from another - do this by identifying clusters of symptoms that occur together and classifying this as one disorder
• systems for classification of mental disorder -

  • ICD-10 and DSM-5
  • differ slightly in classification of schizophrenia
  • DSM-5 system - 1 positive symptom must be present, ICD - 2 or more negative symptoms are sufficient
  • previous editions recognised subtypes - but both have now dropped subtypes because they tended to be inconsistant
• positive symptoms -

  • additional experiences beyond those of ordinary experience
  • hallucinations = unusual sensory experiences - related to events in environment or no relationship to senses in environment (eg hearing voices) - experienced in relation to any sense (eg distorted facial expressions, people or animals who aren't there)
  • delusions = paranoia or irrational beliefs - range of forms (eg being an important figure, being persecuted by government aliens or having superpowers) - believe they're under external control
• negative symptoms -

  • loss of usual abilities and experience
  • speech poverty = changes in patterns of speech - reduction in amount and quality of speech - delay in verbal responses during conversation - however now more emphasis on speech disorganisation - incoherent or speaker changes topic mid-sentence (DSM-5 says positive symptom)
  • avolition - 'apathy' finding it difficult to begin or keep up with goal-directed activity - reduced motivation - 3 signs: poor hygiene, lack of persistence in work or education and lack of energy
• strength of diagnosis: good reliability -

  • P: psychiatric diagnosis is said to be reliable when different diagnosing clinicians reach the same diagnosis for same individual (inter-rater reliability) + when same clinician reaches the same diagnosis for the same individual on 2 occasions (test-retest reliability)
  • E: Osorio et al (2019) report excellent reliability for diagnosis - 180 individuals using the DSM-5 pairs of interviewers achieved inter-rater reliability of +.97 and test-retest reliability of +9.2
  • P: means we can be reasonably sure that the diagnosis is consistently applied
• limitation of diagnosis: low validity -

  • P: validity concerns whether we assess what we are trying to assess
  • E: one way to assess is criterion validity
  • E: Cheniaux et al (2009) had 2 psychiatrists independently assess the same 100 clients using ICD-10 and DSM-IV criteria - found 68 were diagnosed under ICD system and 39 under DSM
  • L: suggests its wither over or under diagnosed according to diagnostic system - suggests criterion validity is low
• strength of diagnosis: counterpoint of low validity -

  • in Osorio et al study reported above there was excellent agreement between clinicians when they used 2 measures to diagnose - both derived from the DSM system
  • means criterion validity for diagnosing is actually good provided it takes place within a single diagnostic system
• limitation of diagnosis: co-morbidity -

  • P: if conditions occur together a lot of the time then this calls into question the validity of their diagnosis and classification because they might actually be a single condition
  • E: commonly diagnosed with other conditions - one review found half of those diagnosed with schizophrenia also had a diagnosis of depression or substance abuse
  • E: problem for classification cause it means schizophrenia may not exist as a distinct condition - problem for diagnosis as some people diagnosed may have unusual cased of conditions like depression
• limitation in diagnosis: gender bias -

  • P: since 1980s men have been more commonly diagnosed then women
  • E: possible explanations - women less vulnerable then men, genetic factors
  • E: more likely women are under diagnosed because they have closer relationships and get more support - leads to women often functioning better than men
  • L: under diagnosis is a gender bias and means women may not be receiving treatment and services that might benefit them
• limitation of diagnosis: culture bias -

  • P: some symptoms (eg hearing voices) have different meanings in different cultures
  • E: eg in Haiti some people believe voices are communications from ancestors
  • E: British people of African-Carribean origin are 9x more likely to receive a diagnosis as white British people
• limitation of diagnosis: symptom overlap -

  • P: considerable overlap between symptoms of schizophrenia and symptoms of other conditions
  • E: both schizophrenia and bipolar disorder involve positive symptoms (eg delusions) and negative symptoms (eg avolition)
  • L: means schizophrenia may not exist as a distinct condition and that even if it does its hard to diagnose - both classification and diagnosis are flawed