issues with diagnosing schizophrenia

• • For a diagnosis of schizophrenia to be reliable it must show consistency and agreement across diagnosing clinicians i.e. the same set of symptoms must be given the same diagnosis regardless of who is doing the diagnosing 
• • Inter-rater reliability refers to if more than one clinician is diagnosing the same patient then they should both/all agree as to the diagnosis 
  • test-retest
  • the extent to which the same diagnostic tool eg DSM provides the same outcome over a long period of time
• issues with reliability occur when (as does happen) clinicians disagree as to the diagnosis

  • Unreliable diagnosis may happen if clinicians do not use the same diagnostic tools e.g. one clinician uses the DSM and other uses the ICD, regardless of year of publication of both of these manuals
• • validity
  • the extent that a diagnosis represents something something that is real and distinct from other disorders
  • and the extent that a classification system such as DSM-5 measures what it claims to measure
  • Rosenhan tested the validity of schizophrenia diagnosis in a field experiment in which he and eight confederates reported false symptoms and were all (but one) admitted to mental hospitals with a diagnosis of schizophrenia 
• • issues with validity
  • symptom overlap- sz shares some symptoms with other disorders
  • such as delusions also being a symptom of bipolar disorder which can lead to confusion in diagnosis
• • Co-morbidity is when one patient may present symptoms (and/or be suffering from) more than one mental illness
• • Symptom overlap is when two or more illnesses have some of the same symptoms e.g. avolition (a negative symptom of schizophrenia) overlaps with symptoms of depression - lethargy, lack of motivation
• — Buckley et al found significant co-morbidity between schizophrenia and other mental health disorders, such as OCD and PTSD. researchers found that 29% of their SZ patients suffered from PTSD, whilst 50% suffered depression. Particularly in the case of depression - suggests that if schizophrenia is so frequently diagnosed with other psychiatric disorders, then these two disorders may be the same - a more accurate and valid method of diagnosis would be to combine these two. Therefore - issues of validity in the diagnosis of SZ and attempting to differentiate symptoms from other disorders.