Classification and diagnosis of Schizophrenia

Positive symptoms

• Delusions- Bizzare beliefs that seem real to the person
• Hallucinations - are bizzare, unreal perceptions of the environment that are usually auditory but may be visual. 
• Disorganised speech
• Catonic behaviour

Negative Symptoms

• Alogia - poverty of speech
• Avolition - reduction of goal directed behaviour
• Affective Flattening - Loss of facial expressions

Reliability is the extent the pscyahtrist can agree n the same diagnosis when independantly assessing the patient. 

DSM III increased reliability --> Led to greater aggreement on who had schizophrenia and who didnt. 

Whaley have found inter rater reliability correlation in the diagnosis of schizophrenia as low as 0.11.

Unreliable symptoms

Klosterkotter et al. assessed 500 admissions to a psych unit in germany to determine whether +tive or -tive symptoms were more suited in diagnoses of schizophrenia. They found that +tive symptoms were more useful in diagnoses. 

Some critics argue that the diagnoses of schizophrenia is too broad. as it is possible to have different behaviours and given the same diagnoses. 

Copeland - Shizophrenic symptoms were described to american and englsih doctors and only 69% of the us gave the right diagnoses and only 2% of uk gave the correct diagnoses

Validity

If scientist cannot agree who has schizophrenia (low reliability) that questions what it is (low validity) becomes esstionally meaningless.

Symptoms

Schnieder – listed the psychotic symptoms that believed distinguished schizophrenia from other psychotic disorders (first rank symptoms). These symptoms provide a more reliable way of diagnosing schizophrenia. However some of these symptoms appear in other disorders. Ellason and Ross point out people with DID actually have more schizophrenic symptoms that some people diagnosed with schizophrenia.

Prognosis

In the same way that people diagnosed as schizophrenic rarely share the same symptoms likewise they do not share the same outcome.