diagnosis and classification

• diagnosis and classification are linked as we need to distinguish between disorders to diagnose
• we classify disorders by identifying clusters of symptoms that occur together
• what are the 2 systems of classification of schizophrenia?

  ICD-10: WHO classification of disease

  DSM-5 : American psychiatric manual
• what are the symptoms that are used in classification of schizophrenia?

  >ICD-10: 2 or negative symptoms

  >DSM-5: 1 positive symptom
• describe positive symptoms of schizophrenia

  >additional experience beyond ordinary experience

  >hallucination: unusual sensory experience can be related to any sense (hearing voices or seeing things)

  >delusion: irrational beliefs such as paranoia which seem bizarre to everyone else and may lead to agression
• describe negative symptoms of schizophrenia

  >loss of usual abilities and experiences

  >speech poverty: change in pattern of speech or incoherent speech (reduction in quality or amount of speech or changing topics mid sentence)

  >speech poverty is classified positive in DSM-5 but negative in ICD-10

  >avolition: apathy and extreme lack of motivation. Andreasen found signs of avolition (poor hygiene, lack of persistence, lack of energy)
• strengths of diagnosis and classification

  +Asorio: prior to DSM low reliability for diagnosis but now clinicians have higher inter rater reliability and test retest reliability

  +counter point to low criterion validity: Asorio found criterion validity good when in single diagnostic system
• limitations of diagnosis and classification

  -low criterion validity: people diagnosed differently using different criteria of ICD or DSM

  -gender bias: men more commonly diagnosed. Cotton found women may not get the treatment they need

  -cultural bias: symptoms (hearing voices) may have different meanings in different cultures, afro carribbean hearing voices are communications form ancestors so may be discriminated against a culturally biased system