DISCUSS ISSUES OF RELIABILITY AND VALIDITY ASSOCIATED WITH THE CLASSIFICATION AND DIAGNOSIS OF SCHIZOPHRENIA (8+16)
AO1: Schizophrenia is a severe mental disorder characterised by a profound disruption of cognition and emotion. This affects a person’s language, thought, perception, affect and even their sense of self.
AO1: Two of the most important classificatory systems for mental disorders, including schizophrenia, are the ‘Diagnostic and Statistical Manual’ (DSM) and the ‘International Classification of Diseases’ (ICD). However, for any diagnostic system to work effectively, it must possess reliability and validity.
AO1: Reliability refers to the consistency of diagnosis. Reliability may be measured in terms of whether tests used to deliver these diagnoses are consistent over time (test-retest reliability) or whether two independent assessors give similar diagnoses (inter-rater reliability).
AO1: The reliability of the main classificatory systems can be questioned as the DSM (used in the US) and the ICD (used in Europe) do not entirely agree on the number of subtypes of schizophrenia; for example the DSM tool recognizes 5 subtypes of Schizophrenia while the ICD tool recognizes 7 subtypes. The issue here is that a sufferer could be diagnosed as one type of schizophrenic according to the DSM (e.g. paranoid) and a different type according to the ICD (e.g. disorganised), indicating low inter-rater reliability between the two systems.
AO1: Moreover, in 1980 a new classification system called ‘DSM-III’ was designed to provide a much more reliable system for classifying mental disorders. Carson claimed that this had fixed the problem of inter-rater reliability once and for all. This meant that there could be much greater agreement over who did, or did not, have schizophrenia.
AO2: However, despite the claims of increased reliability, over 30 years later there is still little evidence that the DSM is regularly used with high reliability by mental health clinicians. This is supported by Whaley who found inter-rater reliability correlations in the diagnosis of S/z to be as low as +.11 this means that when independently assessing patients, the diagnosis was rarely consistent between mental health clinicians meaning that the DSM tool appears to be unreliable in accurately and consistently diagnosing S/z.
AO2:Further problems with the reliability of diagnosis have been illustrated in a study by Rosenhan in which ‘normal’, people presented themselves to psychiatric hospitals in the US claiming they heard an unfamiliar voice in their head saying the words ‘empty’, ‘hollow’ and ‘thud’. They were all diagnosed as having schizophrenia and admitted. Throughout their stay none of the staff recognised that they were actually normal.
AO2: The unreliability of diagnosis was further demonstrated in a follow-up study by Rosenhan. Psychiatrists at several mental hospitals were told to expect pseudo patients over a period of several months. This resulted in a 21% detection rate by the psychiatrists, even though none were actually sent. This shows that the diagnostic criteria used by psychiatrists lacks reliability as the psychiatrists could not reliably identity a person with S/z.
AO2: Rosenhans study raises many ethical issues as none of the staff knew they were being observed and therefore were unable to give their consent to take part in the study.
AO2: Another weakness is that the hospital staff was deliberately deceived by the pseudo patients who claimed that they heard voices, breaking ethical guidelines and wasting staffs time. This time could have been spent treating patients with a genuine mental health disorder
AO2: However, the study has high ecological validity as the staff at the institution were unaware they of the fact they were being studied and were also in their natural environment. Therefore the findings reflect real life.
AO2: Additional research to support the claim that diagnosis of S/z lacks reliability comes from Copeland et al. They gave a description of a patient to US and British psychiatrists and asked them to give a clinical diagnosis. 69% of the US psychiatrists diagnosed S/z compared to only 2% of the British psychologists. This study shows just how unreliable diagnoses can be and further highlights cultural differences.
AO2: However this study proposes generalisability issues as it only included psychiatrists from Britain and the US. Both are Western cultures which mean that the findings cannot be generalised to non-western cultures such as Japan.
AO2: Also, there were only 331 psychiatrists studied in total. This is a very small sample size and may not be representative of the wider population.
AO3: A weakness of the DSM is that it is culturally biased as it was created by Americans for Americans. This may be an issue as behaviour in one culture may not be regarded as a symptom of schizophrenia but according to the DSM it may be. For instance, hearing voices in some cultures is considered to be a message and is regarded as an honour not a symptom of a mental disorder.
AO1: Furthermore, there is no physical cause that can be conclusively measured for Schizophrenia and a great deal of emphasis is placed on the patient’s ability to report the symptoms which may not always be accurately described (possible due to schizophrenia) further hindering reliability of diagnosis.
AO1: One of the main problems with diagnosing schizophrenia is that we do not have objective tests such as blood tests or imaging to determine whether an individual is schizophrenic or not so we have to rely on an assessment carried out by a psychiatrist. Therefore interpretation of symptoms is subjective and down to the person doing the diagnosis so a great deal of importance is placed on the individual’s ability in diagnosis which may vary between health professionals. Therefore skill, experience and knowledge further affect reliable diagnosis.
AO1: The second issue concerns validity. Validity refers to the extent to which a diagnosis represents something that is real & distinct from other disorders and the extent to which classification systems such as ICD and DSM measures what it claims to measure. Reliability and validity are linked because diagnosis cannot be valid if it is not reliable.
AO1: Bentall et al conducted a comprehensive review of research into the symptoms, causes and outcomes of Schizophrenia and concluded that Schizophrenia was not a useful scientiﬁc category. This is because many ‘first-rank’ symptoms of schizophrenia (e.g. delusions of being controlled, the belief that thoughts are being broadcast, hearing hallucinatory voices) overlap with other disorders such as depression and bipolar disorder.
AO2: This is supported by Ellason & Ross who point out that people with dissociative Identity disorder (DID) actually have more Schizophrenic symptoms than people diagnosed with it.
AO1: This raises issues of Comobidity as symptoms may appear to ﬁt in with Schizophrenia however it may be due to a combination of other illnesses that resemble it making diagnosis unreliable and treatment diﬃcult. If we do not accurately know what Schizophrenia is we cannot suﬃciently treat it.
AO1: A second issue regarding validity involves the prognosis of patients. People diagnosed as schizophrenic rarely share the same symptoms, nor is there evidence that they share the same outcomes. The prognosis for patients varies with about 20% recovering from their previous level of functioning, 10% achieving significant and lasting improvement, and about 30% showing lasting improvement with a few relapses. A diagnosis of schizophrenia, therefore, has little predictive validity – some people never appear to recover from the disorder, but many do. This highlights exactly how reductionalist our tools in identification are as we clearly do not understand the disorder or why it varies from one individual to another.
AO2: Ethical issues arise as once patients have been diagnosed they are then labelled as schizophrenic. Those who have suffered a mental disorder must disclose this information when applying from jobs as the label stays with a person throughout their live and they therefore risk carrying the stigma of their condition. Labelling has both advantages and disadvantages.
AO2: One advantage to being diagnosed is the feeling of relief that patients may feel if they have been particularly scared or anxious as they finally have an explanation as to what has been going on in their lives. This is also able to lead them to proper effective treatment that may enable them to live a normal functioning life.
AO2: However, it can be damaging as sufferers have to live with the attached label for the rest of their lives. This may go against them and lead them to unemployment and poverty. Furthermore labels may also lead to a self-fulfilling prophecy where people are treated in a certain way that elicits the expected behaviour.