Diagnosis and Classification of Schizophrenia

• How is schizophrenia classified?

  • 1% of the population have schizophrenia
  • Men are more likely than women to develop schizophrenia, plus they develop it earlier (earlier onset)
  • Positive and Negative Symptoms
• What are Positive symptoms

  symptoms that have been ADDED that are not there in reality

  Additional experiences beyond those of ordinary experience
• Example of positive symptoms

  Hallucinations

  • Unusual sensory experiences
  • Some are related to events in environment
  • Can be experienced in relation to any sense
• Example of Positive Symptoms

  Delusions 

  • Also known as paranoia
  • Irrational beliefs (about the world)
  • Commonly involved famous figures e.g Jesus or Napoleon
  • May believe they are under external controls
  • Can make person behave in a way that seems sane to them, but abnormal to those around them
• What are Negative Symptoms?

  Loss of usual abilities or experiences
• Example of Negative Symotion

  Speech poverty

  • Changes in speech patterns
  • Brief verbal communication style
  • Reduction in amount and quality of speech
  • Excessively disorganised in what they are saying, and often trail off the point of focus
• Example of negative symptom

  Avolition 

  • Also known as ‘apathy’
  • Finding it difficult to being or keep up with goal-directed activities

  Nancy Andreasen: poor hygiene and grooming, lack of energy, lack of persistence in work or educatio
• What are the two major systems for classifying schizophrenia?

  ICD10 - International Classification of Diseases

  • One positive symptom must be present to be diagnosed
  • DSM-5 - Diagnostic Statistical Manual
  • Two or more negative symptoms must be present to be diagnosed
• What is Comorbidity?

  The extent to which two or more conditions occur at the same time

  • Half of those diagnosed with schizophrenia were diagnosed with depression or substance abuse
• The introduction of DSM-5 improved schizophrenia diagnosis
• Flavia Osaria


  Excellent reliability diagnosing schizophrenia in 180 individual using the DSM-5
• Reliability

  • Inter-rater reliability of +.97
  • Test-retest reliability of +.92
• Reliability

  How consistent results are using the same measuring tool
• Since there was a high inter-rater reliability as well as test-retest reliability, the diagnosis of schizophrenia through the DSM-5 system is clearly very accurate, and reliable
• Beck (1963)


  Reviewed the diagnosis of 153 schizophrenic patients by multiple doctors
• The results showed only a 54% concordance rate between the doctor's assessments/diagnosis
• This means the inter-rater reliability of this diagnosis is low, and therefore many people may either be misdiagnosed or those who are schizophrenic are not being diagnosed - and either patients are being given incorrect medication or help
• A03: Low validity

  Ellie Cheniaux: had 2 psychiatrists independently assess 100 patients using either the ICD-10 DSM-5 system.

  She found that 68 people were diagnosed under the ICD, whilst 39 using the DSM.

  Criterion validity: how we assess validity of a psychiatric diagnosis

  This shows the diagnosis systems lack criterion validity as people are either being under-diagnosed or overdiagnosed, which is harmful.
• A03: Culture bias: Limitation

  In Haiti, some people believe hearing voices is a means of communicating with ancestors

  African-Caribbean Brits are 9 times more likely to get a diagnosis to White Brits; however, people of african-caribbean origin living in those og countries are not

  Some symptoms of schizophrenia, such as hearing voices are not seen as ‘symptoms’ in some cultures - have good connotations

  Culture bias in diagnosis of clients from a different cultural background. Leads to an overinterpretation of symptoms in black British people
• A03: Gender bias: Limitation

  Since 1980’s, men have been diagnosed with schizophrenia more than women - Fisher and Buchanan: ratio of 1:4:1

  Women may be less vulnerable to schizophrenia