diagnosis and classification

• 2 systems of classifying mental disorders

  1. world health organisations international classification of disease edition 10 - ICD—10
  2. american psychiatric association‘s diagnostic and statistical manual edition 5 - DSM-5
• for classification of schizophrenia in DSM system, one positive symptom must be present for diagnosis
• two or more negative symptoms must be present for diagnosis in ICD system
• ICD subtypes of schizophrenia

  1. paranoid - powerful delusions and hallucinations
  2. hebephrenic - primarily negative symptoms
  3. catatonic - disturbance to movement where sufferer is immobile or alternatively overactive
• positive symptoms - additional experiences beyond those of ordinary existence
• hallucinations - positive symptom


  sensory experiences of stimuli that either have no basis in reality or are distorted perceptions of things that are there
• delusions - positive symptom


  irrational beliefs that have no basis in reality

  delusions of grandeur - thinking you are very powerful and have god like powers

  delusions of persecution - when you are convinced that someone panning to harm or is conspiring against you
• negative symptoms - loss of usual abilities and experiences
• avolition - negative symptom 


  difficulties to begin or keep up with goal directed activities due to a lack of motivation

  andreason - 3 identifying signs of avolition

  1. poor hygiene and grooming
  2. lack of persistence in work
  3. lack of energy
• speech poverty - negative symptom 


  reduced amount and quality of speech. often accompanied by a delay in verbal responses
• X low reliability in diagnosis - cheniaux - 2 psychiatrists independently diagnose 100 patients according to DSM and ICD criteria.

  • poor interrater reliability as one psychiatrist diagnosed 26 according to DSM and 44 according to ICD and the other diagnosed 13 according to DSM and 24 according to ICD
• X poor validity - cheniaux study shows that schizophrenia is either over diagnosed in ICD or under diagnosed in DSM
• criterion validity - do different assessment systems arrive at the same diagnosis for the same patient
• morbidity - refers to a medical condition or how common it is
• co-morbidity - the phenomenon that 2 or more conditions occur together
• X if conditions occur together a lot of the time then the validity of the classification and diagnosis can be questioned as it might just be a single condition

  • buckley et al - around half of patients diagnosed with schizophrenia also had a diagnosis of depression or substance abuse
  • ptsd and ocd also occurred in cases
• symptom overlap - overlap between the symptoms of schizophrenia and other conditions

  X questions the validity of the classification and diagnosis of schizophrenia
• X gender bias in diagnosis

  • appears that female patients typically function better than men and have better relationships with family so their interpersonal functioning may cause bias for doctors when diagnosing schizophrenia, explaining why some women haven't been diagnosed but some men with the similar symptoms may have
• X cultural bias - african americans are more likely than white people to be diagnosed in western countries

  • positive symptoms such as hearing voices may be more acceptable in african cultures because of cultural beliefs in communication with ancestors so more people are ready to acknowledge such experiences
  • when reported to a psychiatrist from a different culture, these experiences are more likely to be seen as irrational
  • javier escobar pointed out that white psychiatrists may tend to over interpret symptoms and distrust the honesty of black people