Diagnosis & Classification

• Prevalence:

  • Serious mental disorder affecting 1% of the population
  • More commonly affects males, city-dwellers and lower socioeconomic groups.
• Diagnosis & Classification are interlinked - in order to diagnose we must be able to distinguish one disorder from another.

  • Diagnosis: Identify symptoms and use classification system to identify the disorder.
  • Classification: Identify symptoms that go together with the disorder.
• Classification Systems of Schizophrenia:

  • DSM-5: One positive symptom must be present to classify as schizophrenia. (i.e. delusions, hallucinations)
  • ICD-10: Two main symptoms which are negative must be present. (i.e. speech poverty, avolition)
• Positive Symptoms: Additional sensory experiences which go beyond those of ordinary existence.
• Negative Symptoms: Loss of usual abilities and experiences.
• Positive:

  • Delusions: Thoughts or ideas which have no basis in reality. (I.E being a victim of conspiracy, strong beliefs about a very important person).
  • Hallucinations: Additional sensory experiences which have no basis in reality. (i.e. hearing voices, seeing people that aren't there).
• Negative:

  • Speech Poverty: A reduction in the quality of speech - DSM emphasises speech disorganisation and incoherency as a positive symptom.
  • Avolition: A severe lack of motivation to complete every day tasks which results in lowered activity levels and unwillingness to do things.
• Strength of Diagnosis:

  • Diagnosis of schizophrenia has good reliability as it is consistent between clinicians (inter-rater) and between occasions (test-retest)
  • Osorio et al (2019) report excellent reliability for schizophrenia diagnosis (DSM-5) - inter rater agreement of +.97 and test-retest reliability of +.92
  • Meaning the diagnosis of schizophrenia is consistently applied.
• Limitation of Diagnosis:

  • Co-Morbidity with other conditions
  • If conditions often co-occur then they might be a single condition - schizophrenia is commonly diagnosed with other conditions.
  • Buckley et al. (2009) concluded schizophrenia is co-morbid with depression (50% of cases), substance abuse (47%) or OCD (23%)
  • This suggeststhat schizophrenia may not exist as a distinct condition.