Paper 3: Schizophrenia Flashcards
problems with validity in diagnosing SZ?
chineaux et al found in a study w 2 psychiatrists that the DSM was much more likely to diagnose SZ than the ICD (44 diagnosed w ICD and 26 diagnosed w DSM in case of 1 psychiatrist) either 1 system is over diagnosing or the other system is under diagnosing. either way highlights an issue with concurrent validity.
problems with reliability in diagnosing SZ?
poor inter-rater reliability - in the chineaux et al study, the two psychiatrists used differed significantly in diagnosis even when using the same system (eg 44 vs 24 diagnoses when using ICD)
positives of reliability in diagnosing SZ?
jakobson et al tested reliability of the ICD-10 and found an inter-rater reliability of 98% - contrasts with chineaux et al research
what is the issue with symptom overlap?
many symptoms of SZ (including hallucinations and delusions) are shared by other disorders, such as bipolar. this poses a significant issue with validity in diagnosing SZ as it can be difficult to distinguish disorders at times.
A consequence of this issue could mean that individuals are misdiagnosed which can
lead to years of delay in receiving relevant treatment, during which time suffering and
further degeneration of symptoms can occur for the individual.
what is the issue of co-morbidity?
comorbidity is an issue for the diagnosis and classification of
schizophrenia. Different diagnoses could be given for the same person; in one
instance they could be diagnosed with schizophrenia, diagnosed with bipolar in
another instance or they could be diagnosed with both conditions. This issue could
lead to inconsistencies in diagnoses between clinicians in relation to which disorder is
diagnosed e.g. Schizophrenia or Depression, creating problems for the reliability of
diagnosis.
study into co-morbidity?
Buckley et al. (2009) concluded that
around half of patients with a diagnosis of schizophrenia
also have a diagnosis of depression (50%) or substance abuse (47%). Posttraumatic stress disorder also occurred in 29% of cases and OCD in 23%.
what is the issue of cuture bias?
Culture bias is another problem which affects the validity
of diagnosis. Although cross-cultural research of
schizophrenia suggest a similar prevalence across races,
research has shown that Schizophrenia, despite culturally
formulated updates to diagnostic manuals, is repeatedly
diagnosed at a higher rate in the African American population.
This is an issue as it suggests a lack of validity in diagnosing schizophrenia in people
of African-American origin as differences in symptom expression are overlooked or
misinterpreted by clinicians. The consequence of the misdiagnosis is that it prevents
them receiving the optimal treatment for their disorder and puts them at risk of the
side effects of medication taken for schizophrenia, such as diabetes and weight gain.
study into culture bias?
Cochrane (1977) reported the incidence of schizophrenia in the West
Indies and Britain to be similar, at around 1%, but that people of Afro-Caribbean
10
origin are 7 times more likely to be diagnosed with schizophrenia when living in
Britain. Considering the incidence in both cultures is very similar this suggests that
higher diagnosis rates are not due to a genetic vulnerability, but instead may be
due to a cultural bias
Gara et al (2019) found that African American men with severe depression tend to
be misdiagnosed with schizophrenia in comparison to other racial groups. The findings
suggest that clinicians put more emphasis on psychotic than depressive symptoms in
African-Americans, which skews diagnoses toward schizophrenia even when these
patients show similar depressive and manic symptoms as white patients.
what is the issue of gender bias?
The tendency for diagnostic criteria to be applied differently to male and
females and for there to be differences in
the classification of the disorder.
study into gender bias?
Loring and Powell (1988) - had 290 male and female psychiatrists make judgements on descriptions of patients. when patients were described as male or gender not specified, 56% of psychiatrists gave a SZ diagnosis for the patients. when they were described as female only 20% were diagnosed.
what is the genetic link theory of SZ?
this is the theory that SZ is passed on through genes. the closer related two relatives are, the more likely they are to both have SZ (eg parent and child are 50% similar)
supporting evidence for genetic link theory?
gottesman (1991) - conducted a large-scale family study and found a strong
relationship between the degree of genetic similarity and shared risk of schizophrenia.
For example, 48% concordance rate in MZ twins in comparison to 17% in DZ twins.
what is the polygenic explanation for SZ?
because studies have identified different candidate genes it also
appears that schizophrenia is aetiologically heterogenous,
i.e. different combinations of factors can lead to the condition.
supporting evidence for the polygenic explanation for SZ?
Ripke et al. (2014) carried out a huge study combining all previous data from
genome-wide studies (i.e. those looking at the whole genome as opposed to
particular genes) of schizophrenia. The genetic make-up of 37,000 patients was
compared to that of 113,000 controls; 108 separate genetic variations were
associated with increased risk of schizophrenia.
Genes associated with increased risk included those in the brain and in tissues with
an important role in immunity, as well as those coding for functioning of a number of
neurotransmitters including dopamine. This supports the overall idea of a biological
causation in the disorder.
