Classification and dianosis of Scizophreina PSYA4

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A01- Clinical Characteristics

Positive Symptoms (Things they do have which they shouldnt) DEHD

  • Delusions- bizzare beliefs, paranoia distortion of power or imporance.
  • Experiences of control- under control of an alien
  • Hallucinations- unreal expectation of enviroment, hears noices etc.
  • Disordered thinking- feeling that thoughts are being inserted or can be taken away.

Negative Symptoms (Things they dont have which they should) AAA

  • Affective flattening- reduction of emotion, facial expression, eye contact etc.
  • Alogia- no speech fluency, slow or blocked thoughts.
  • Avolition- lack of goal directed behaviour shown in doing nothing can be mistaken for no interest.

Clinical Characteristics

  • Profound disruption of cognition and emotion- affects language, perception and sense of self.
  • Diagnosis of schizo- under DSM-IV requires at least one-month duration of two or more positive symptoms.
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A02- Reliability of Classification

  • Inter-rater reliability- DSM-111 and later versions claim increased reliability of diagnosis.
  • Test-retest reliability- screening tests show high test-retest reliability.


  • Inter-rater reliability- despite claims for increased reliability, there is still little evidence that DSM is routinley used with high reliability by mental health clinicians.
  • On being sane in unsane places by Rosenhan he showed there is a flaw in diagnosis.
  • Unreliable symptoms- diagnosis of bizzare delusions not a reliable method of distinguishing between schizo and non-schizo patients.
  • Comparing DSM and ICD- schizo was more fequently diagnosed according to ICD-10 than DSM-IV criteria.
  • Reliability of diagnosis challenged by difference between US and UK diagnoses.
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AO2 Validity

  • Psychiatric comorbidities (when two or more conditions occur e.g substance abuse along with schizo) are common among patients with schizo and create difficulties in diagnosis of schizo.
  • Positive symptoms are more usualful for diagnosis than negative symptoms.
  • Prognosis- people diagnosed as schizophrenic rarely share the same symptoms, nor the same outcomes.


  • Comorbidity and medical complecations- Weber found evidence of many comorbid non-psychiatric diagnoses among patients with schizo which affects prognosis.
  • Comorbidity and suicide risk- persons with schizo at risk of suicise with comorbid depression the major cause for suicidal behaviour.
  • Ethnicity and misdiagnosis- rates of schizo amonth african- carribeans much higher than white populations maybe an effect of misdiagnosis.
  • Symptoms- schizophrenic symptoms also found in many other disorders including depression.
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  • Rosenhans study- showed the flaws in the diagnosis of schizo, nearly all of the participants in the study including rosenhan himself were diagnosed with schizophrenia and it took them a while to be released.
  • Cultural Diagnosis- there is a massive variation in cultures, 134 US and 194 UK doctors a description of a patient 69% of US and only 2% of Brits gave diagnosis.
  • Cognitive Proccesses- lends itself strongly to scientific studies which makes for a strong correlation between cognitive malfunction and a psychopathological disorder.
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