Classifying and Diagnosing Schizophrenia

• What are Positive symptoms of Sz?


  An excess or distortion of normal behaviour
• What are Negative symptoms of Sz?

  A reduction or loss of normal behaviour
• What are the 3 positive symptoms of Sz?

  • Hallucinations
  • Delusions
  • Disorganised Speech
• What are Hallucinations?

  Sensory experiences that have no basis in reality - the most common are auditory hallucinations but they can also be visual, tactile, or olfactory
• What are Delusions?

  Beliefs that have no basis in reality - delusions will make sense to the person with Sz but will seem bizarre to others
• What is Disorganised Speech?

  The person will struggle to speak coherently - They may skip words or slide from one topic to another midsentence
• What are the 3 Negative symptoms of Sz?

  • Speech Poverty
  • Avolition
  • Affective Flattening
• What is Speech Poverty?

  A reduction in the amount and quality of speech
• What is Avolition?

  A loss of interest in activities that would usually be enjoyed
• What is Affective Flattening?

  The person will not express emotion easily - This could be seen in their facial expressions, or heard in their tone of voice, or shown in their body language
• What are the 2 manuals used to diagnose Sz?

  • DSM

  or

  • ICD
• How is Sz diagnosed using the DSM?

  A person must show two or more symptoms for at least a month

  • At least one symptom has to be positive
• How is Sz diagnosed using the ICD?

  A person must show two or more symptoms for at least a month

  • Two negatives are sufficient
• What is Validity?

  • The quality of being logically or factually correct
  • If a person receives a Sz diagnosis, they truly do have it
• What is Reliability?

  • Consistent in quality or performance; able to be relied upon
  • The classification always results in the same diagnosis regardless of who uses it
• What factors can affect the Validity or Reliability of Sz diagnosis?

  • Inter-rater reliability
  • Culture Bias
  • Gender Bias
  • Co-morbidity
  • Symptom overlap
• Inter-rater reliability research evidence:

  • Researchers gave two psychiatrists descriptions of 100 patients. They were asked to diagnose them using the DSM and the ICD
  • One psychiatrist diagnosed 26 using the DSM and 44 using the ICD
  • The second psychiatrist diagnosed 13 using the DSM and 24 using the ICD
• Culture bias research evidence:

  Research has found that African-Americans are 2.4 times more likely to be diagnosed with Sz than white individuals
• Gender Bias research evidence:

  • A study asked 290 psychiatrists to read a case study of a patient's behaviour and give them a diagnosis
  • When the patient was described as male, 56% gave a diagnosis
  • This dropped to 20% when the patient was described as female
• Co-morbidity research evidence:

  Research has found that patients with Sz:

  • 50% also have depression
  • 47% also have a substance abuse disorder
  • 25% showed characteristics of OCD
• Symptom overlap research evidence:

  Bipolar disorder also has symptoms of delusions and avolition