Symptom overlap

• SZ symptoms are not exclusive to SZ, therefore certain symptoms overlap with other conditions

  e.g. bipolar disorder can also involve delusions, depression can also include avolition
• Reliability

  • The main thing affecting reliability is the classification systems - the ICD-10 and the DSM-5 have different criteria for a SZ diagnosis
  • ICD-10: 2 (or more) negative symptoms for 1 month (or more)
  • DSM-5: 1 (or more) positive symptom for 6 months (or more)
  • = people with the same symptoms may recieve different diagnoses
  • if psychiatrists use different methods, they may have different diagnoses, therefore low inter-rater reliability
• Validity

  • Due to symptom overlap, accurate diagnoses are difficult and misdiagnoses are common
  • Ophoff
  • 50,000 ppts
  • 3/7 gene locations of the genome associated with SZ were also associated BPD
  • therefore these conditions are difficult to diagnose (misdiagnosis is common), resulting in patients recieving the wrong treatment