Classification and diagnosis of schizophrenia

classification

process of organising symptoms into categories based on which symptoms appear to cluster together in people who appear to be mentally ill

classification systems for schizophrenia

1. Diagnostic statistical manual (DSM)- developed by American Psychiatric association

2. International classification of diseases (ICD)- developed by world health organisation

diagnosis

refers to identifying which (mental) illness someone has based on the symptoms they are experiencing so that a label is assigned

positive symptoms

Symptoms that are experienced in addition to normal behaviour/experiences

Positive experiences of schizophrenia

hallucinations and delusions

Types of hallucinations experienced in schizophrenia

• visual

• Auditory

Type of delusions experienced in schizophrenia

• delusions of grandeur- having an unrealistically inflated sense of yourself of your achievements (e.g. believing you are god)

• Delusions of persecution- believing that someone is mistreating you, conspiring against you, or planning to hurt you or a loved one

• Delusions of reference- believing that un-related occurrences in the external world have a special significance for the individual e.g. watching a movie and believing it is a message for them

Negative symptoms

symptoms that are experiments which are a loss of normal behaviour

Negative symptoms of schizophrenia

• avolition- extreme loss of motivation to initiate or persist with tasks

• Speech poverty- reduced frequency and quality of speech

Discuss reliability in terms of the classification and diagnosis of schizophrenia

poor reliability

• Two different classification systems is a lack of standardisation therefore someone could meet diagnostic criteria under one system and not the other

• Interpretation of symptoms/diagnostic criteria is subjective. For example someone speaking slowly could be classed as speech poverty by some but not others therefore will be classified as meeting diagnostic criteria by one clinician but not another.

• Cheniaux has two psychiatrists independently diagnose 100 patients using both DSM and ICD criteria. In DSM 26 and 13 where diagnosed by P1 AND P2 and in ICD 44 and 24 where diagnosed- this shows poor inter-party reliability which is an important measure of inter-party reliability

Good

• osorio found inter-party reliability of 180 individual cases was +0.97 (very consistent as above 0.8)

Discuss valiidty in terms of classification and diagnosis of schizophrenia

Poor

• Accuracy of diagnosis- criterion validity (do different assesment systems arrive at the same diagnosis) is a measure of validity. Cheniaux study suggests this it is much more likely to be diagnosed using ICD rather than DSM. Suggests schizophrenia is either over-diagnosed in ICD or under-diagnosed in DSM, either way this is poor Validity in either one or both systems

• Systems overlap- two or more conditions share the same symptoms. For example schizophrenia and bipolar both involve positive symptoms like delusions and negative symptoms like avolition (are they same disorder?). Under ICD criteria Patient might be diagnosed with schizophrenia but may receive a diagnosis of bipolar under DSM. Calls into question validity of classification systems

• Co-morbidity- the occurrence of two illnesses or conditions together. If conditions occur together a lot of time, calls to question validity of classification and subsequent diagnoses because they might actually be single condition. Buckley concluded around half of patients diagnosed with schizophrenia also had a diagnosis of depression or substance abuse. So severe depression could look a lot like schizophrenia and nice versa.

Gender bias in classification of schizophrenia

• diagnosed more frequently in men than it is in women (men twice as likely to be diagnosed). May be because women are genetically less venerable to schizophrenia than men. However, it could also suggest there is gender bias in classification and diagnosis of schizophrenia. If so this is a form of sexism leads to women being discriminated against as they are less likely to receive treatment if they are less likely to be diagnosed. Some suggest women with schizophrenia are able to function better because they have a closer relationship with people so get more support, which means they are under diagnosed.

Cultural bias in diagnosis of schizophrenia

• Afro-carribean people living in the UK are up to 10 times more likely to receive a diagnosis of schizophrenia than white people living in the uk. However, Afro-carribean people living in Afro-carribean countries are no more likely to be diagnosed. Suggests not that they are more genetically venerable but that there is cultural bias in the diagnosis of clients by psychiatrists from different cultural backgrounds who may misinterpret normal behaviour as symptoms in people whose cultural backgrounds they do not understand (for example in some Afro-carribean cultures hearing voices is attributed as communication from ancestors and perfectly normal)

Strength of diagnosis and classification of schizophrenia

• better than nothing- even if the validity and reliability is not perfect, they do provide practitioners with a common language, permitting communication of research ideas and findings which may ultimately lead to a better understanding of the disorder and development of treatment