Schizophrenia is a psychotic disorder characterised by a loss of touch with reality. Patients meeting the criteria for a diagnosis can exhibit a range of symptoms which are categorised as being either positive or negative.
Positive symptoms include hallucinations (auditory, visual, and tactile), inappropriate delusions (of grandeur and power), thought control and disordered thinking. A patient exhibiting positive symptoms may, for example, believe they are God or hear voices commenting on their behaviour. Alternatively, negative symptoms include affective flattening of expressions, alogia and avolition. For instance they may show no emotional expressions or speak slower.
In order to be diagnosed with the disorder using DSM 5, 2 or more positive symptoms must persist for at least a month. However, if the delusions are bizarre or a voice is keeping a running commentary on the individual, the diagnosis can be made with just one symptom.
There are also other criteria’s that must be met in order to be diagnosed with schizophrenia, for example criteria B: social/occupational dysfunction, where for a significant portion of time one or more major areas of functioning e.g work or relationships should be markedly lower than the level prior to onset. A second example of criteria to be met is criteria E: exclusion of known organic causes - the doctor must ensure that the disturbance is not due to the direct effects of drugs (such as LSD, causing hallucinations for example) or a brain disorder.
The main tool of measurement to classify and diagnose schizophrenia is the Diagnostic Statistical Manual (DSM-IV). One issue present is the tool’s reliability, which refers to the consistency of a measuring instrument, such as DSM-IV. This can be measured in terms of whether two independent assessors give similar scores (inter-rater reliability), or whether tests used to deliver the diagnoses are consistent over time (test-retest).
Despite the claims for increased reliability in DSM-III (and later revisions), even now (30 years later) there is still little evidence that the DSM is routinely used with high reliability by mental health clinicians. Whaley (2001) found inter-rater reliability correlations in the diagnosis of schizophrenia as low as +.11. Similarly, Mojtabi and Nicholson (1995) asked senior psychiatrists to differentiate between bizarre and non bizarre delusions, with the results showing a correlation of only .4. Both of these points show that the DSM distinctly lacks inter-rater reliability, which is a serious downfall of the DSM as it shows that many doctors and psychiatrists may be misusing it.
In addition, cultural interpretations also pose a threat to the reliability of the diagnosis of schizophrenia. Copeland (1971) gave a description of a patient showing clinical characteristics associated with schizophrenia to 134 US and 194 UK psychiatrists.
Of the US psychiatrists, 69% diagnosed schizophrenia, whereas only 2% of the UK psychiatrists gave the same diagnosis. This leads to suggest that the diagnostic criteria is culturally biased, which reduces the reliability between cultures.
Similarly, Harrison et al (1997) found that the incidence rate for schizophrenia was 8 times higher for afro-caribbean groups than for white groups. Some of this difference could be explained as a result of poor housing and higher rates of unemployment (and other similar factors) but it is possible that mis diagnosis could be the result of cultural differences in language and mannerisms between black patients and white clinicians.
Both of the above points indicate that the DSM lacks validity, as it fails to take cultural differences into account. This is a negative for the DSM, as it is so widely used across the world that you would think it was fully applicable to any type of culture.
In addition, the reliability of diagnosing schizophrenia is challenged through Rosenhan (1973) who claimed that situational factors were more important in determining the ultimate diagnosis of schizophrenia, rather than any specific characteristics of the person.
This was demonstrated through Rosenhan’s ‘Being Sane in Insane Places’ where various patients presented themselves to psychiatric hospitals in the US claiming to be hearing voices (a positive symptom of schizophrenia). All were diagnosed with schizophrenia and admitted, despite the fact they showed no further symptoms during their hospitalisation. Throughout their stay, none of the staff recognised they were normal and interpreted all their behaviour as being symptomatic of schizophrenia- for instance waiting for dinner before the canteen opened was diagnosed as characteristic of schizophrenia, though there was little else for them to do.
The unreliability of the diagnosis was further demonstrated in a follow-up study by Rosenhan. Psychiatrists at several mental hospitals were told to expect schizophrenic patients over a period of several months. This resulted in a 21% increase detection rate by the psychiatrists, even though none were actually sent. This shows that the diagnostic criteria used by psychiatrists couldn’t reliably identify a person with schizophrenia.
Alternatively, validity refers to the extent that the classification system such as DSM measures what it claims to measure. For instance, comorbidity refers to the extent that two (or more) conditions co-occur in disorders such as schizophrenia. Therefore comorbidity is the extent to which the condition is ‘real’ and distinct.
One way to avoid the issue of comorbidity is to use first-rank symptoms of schizophrenia when diagnosing (e.g. delusions and hallucinations) - Klosterkotter et al (1994) assessed 500 psychiatric admissions to Germany to determine whether positive or negative symptoms are more valid for a diagnosis of schizophrenia and found positive symptoms to be more valid. However, Bentall et al (1988) claimed that many of the first-rank symptoms of schizophrenia are also found in other disorders (such as depression and bipolar). This makes it difficult to separate schizophrenia as a distinct disorder because there is crossover in symptoms; therefore schizophrenia is not a distinct condition.
This leads on to an ethical problem – Weber et al (1995) found that a diagnosis of schizophrenia can lead to a lower standard if general medical care for a patient. They also found that many patients were also found to have medical problems such as type 2 diabetes, hypertension and hyperthyroidism and that these conditions coupled with the lack of general medical care could have a negative effect on a sufferer’s prognosis. This is unethical as it suggests that patients diagnosed with schizophrenia are receiving lower levels of medical care, which could mean they will be suffering for longer than they need to or even that they may never fully recover.