Schzophrenia

• Schizophrenia is a mental disorder suffered by about 1% of the population. more commonly diagnosed in men than women, more in cities than in rural areas, and in working-class people. The average age of onset is 18 in men and 25 in women. Schizophrenia is a psychotic disorder
• SZ has positive symptoms ( which are additional experiences) like hallucinations which is characterized by a distortion of real stimuli which have no basis in reality
• Delusions - false beliefs that are not based on reality, but are strongly held and often involve persecution
• Negative symptoms include = speech poverty which is where there is an abnormally low level of the frequency and quality of speech

  
  

  Avolition = A reduction in interests, desires and goals and a behavioural reduction , avolition means the inability to cope with the normal pressures and motivations associated with everyday living and day-to-day task
• the two main classification systems for SZ is the ICD which is British as it is under the World Health Organisation and the DSM edition 5 which is American
• the main difference between the two systems are for the DSM-5 (American) having one positive system ( hallucinations/delusions) is enough to be diagnosed with schizophrenia

  WHEREAS for the ICD 2 or more negative symptoms (speech poverty/ avolition) is needed to be diagnosed with SZ
• Reliability and validity in diagnosis of SZ

  
  

  Reliability - refers to consistency. When two independent psychiatrists agree on a diagnosis of schizophrenia it means it has high inter-rater reliability. If a diagnostic system is to be valid, it must also have high reliability

  
  

  Validity- refers to the extent to which we are measuring what we intend to measure

  One way to assess the validity of a diagnosis of schizophrenia is criterion validity. This refers to using two different measures which diagnose schizophrenia and seeing if they arrive at the same diagnosis - so using both ICD and DSM
• Evidence against reliability and validity of SZ

  Cheniaux et al (2009) -

  DID - Two psychiatrists independently diagnosed 100 patients using DSM and ICD.

  FOUND - One psychiatrist diagnosed 26 patients with Schizophrenia using DSM and 44 according to ICD. The other diagnosed 13 using DSM and 24 according to ICD.

  SHOWS -the two diagnostic systems not agree but different psychiatrists interpret the criteria differently
• Factors affecting reliability and validity include co-morbidity, gender bias in diagnosis, cultural bias in diagnosis and system overlap
• What is co-morbidity?

  It's when schizophrenia is commonly diagnosed alongside other conditions. For example 50% of schizophrenic patients also have depression
• What is system overlap?

  There is considerable overlap between symptoms of schizophrenia and other conditions. For example, both SZ and bipolar disorder have symptoms of delusions and avolition. Using the ICD a patient is more likely to be diagnosed with schizophrenia, but the same patient may be seen as bipolar using the DSM.