4.3.5 Schizophrenia Flashcards
1
Q
schizophrenia
A
- a psychological disorder characterised by a loss of contact with reality
- affects around 1% of the world’s population
- affects thought processes and the ability to determine reality
2
Q
classification of schizophrenia
A
- schizophrenia doesn’t have a single defining characteristic as it’s a cluster of symptoms, some of which appear to be unrelated
- these symptoms may be positive or negative
3
Q
positive symptoms of schizophrenia
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- atypical experiences in addition to normal experiences
- hallucinations; distorted perceptions of reality or perceptions that aren’t even based in reality
- e.g. a sufferer may see distorted faces, or occasionally, people that aren’t even there
- delusions; irrational beliefs with no basis in reality
- e.g. a sufferer may have a delusion that they’re an important figure, such as Jesus
- different types of delusions include that of persecution, grandeur (they’re someone of a high-status) , jealousy, erotonomia (someone’s in love with them), or somatic (something’s wrong with them)
4
Q
negative symptoms of schizophrenia
A
- a lack of normal experiences
- speech poverty; a reduction in the quality and amount (frequency) of speech
- e.g. a sufferer may give one-word answers to questions without elaborating any further detail
- avolition; a lack of interest, desire and motivation for anything
- i.e. the inability to cope with the normal pressures and motivations associated with everyday tasks
- e.g. a sufferer may sit around without engaging in daily tasks such as work, socialising, or maintaining personal hygiene
5
Q
diagnosis of schizophrenia
A
- the 2 types of classification systems for diagnosing mental disorders are the DSM-5 (the american psychiatric association’s diagnostic and statistical manual) and the ICD-10 (WHO’s international classification of disease)
- these 2 systems have different requirements for the diagnosis of schizophrenia; DSM-5 requires at least one positive symptom to be present, whereas the ICD-10 can base a diagnosis on negative symptoms alone
6
Q
reliability of diagnosis
A
- refers to how consistently schizophrenia is diagnosed
- inter-rater reliability; the extent to which multiple doctors arrive at the same diagnosis for the same patients
- if it’s diagnosed inconsistently it can be problematic as it may be over / under-diagnosed by psychiatrists, so patients will be incorrectly labelled as schizophrenic or not diagnosed at all, meaning they won’t receive the treatment they need
7
Q
reliability of diagnosis - strengths
A
- there have been improvements in inter-observer reliability as more recent studies of schizophrenia diagnosis generally find higher concordance rates among psychiatrists, suggesting it’s become more reliable over time
- Soderberg et al. (2005) found a concordance rate of 81% among psychiatrists using the DSM classification to diagnose schizophrenia
- the reliability of diagnosis for schizophrenia is higher than other disorders, e.g. 81% concordance for this, vs 63% for anxiety disorders
8
Q
reliability of diagnosis - limitations
A
- low inter-rater reliability and poor reliability between the DSM and ICD; Cheniaux et al. (2009) had 2 psychiatrists independently diagnose 100 patients using both DSM and ICD criteria. psychiatrist 1 found 26 patients according to DSM and 44 with ICD. psychiatrist 2 found 13 patients according to DSM and 24 with ICD
- co-morbidity or symptom overlap can reduce the reliability of diagnosis as different doctors may diagnose patients with different diseases
9
Q
validity of diagnosis
A
- the extent to which the classification of schizophrenia is a true reflection of the illness the patient is suffering from, i.e. does it measure what it’s intended to measure
- i.e. refers to how genuine the diagnosis is
- Rosenhan (1973) questioned the validity of schizophrenia diagnosis in his study;
- 8 healthy volunteers presented themselves to various psychiatric hospitals claiming to hear voices
- all 8 ppts were successfully admitted to the hospitals and diagnosed with schizophrenia
- depending on the ‘patient’, doctors took between 8-52 days to release them
- in a later experiment, doctors were falsely told that healthy patients would attempt to admit themselves, which led to doctors turning away genuine schizophrenic patients as they thought they were actors
- the results of these experiments suggest the doctors didn’t have valid methods for diagnosing schizophrenia
10
Q
validity of diagnosis - strengths
A
- improvements in validity; more recent studies, after Rosenhan’s, suggest schizophrenia diagnosis has become more accurate
- e.g. Mason et al. (1997) found that improvements to diagnostic manuals (DSM and ICD) over time led to more accurate diagnosis of schizophrenia
11
Q
validity of diagnosis- limitations
A
- Rosenhan’s (1973) study
- co-morbidity
- symptom overlap
- gender bias
- culture bias
12
Q
limitations of validity - co-morbidity
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- refers to the presence of 2 or more disorders occurring simultaneously in a patient
- e.g. schizophrenia and depression - Buckley et al. (2009) found that around 50% of schizophrenia patients also have depression, or substance abuse (47%). PTSD also occurred in 29% of cases and OCD in 23%
- it can lead to inconsistent diagnoses between clinicians in relation to which disorder is diagnosed, i.e. schizophrenia, or depression, or both, which also causes issues with reliability
- Jeste et al. (1996) also stated that schizophrenics with co-morbid conditions are excluded from research, but they form the majority of patients, suggesting that research findings into the causes of schizophrenia can’t be generalised to most sufferers
13
Q
limitations of validity - symptom overlap
A
- when different mental illnesses have similar symptoms so making an accurate diagnosis is difficult
- e.g. schizophrenia and bipolar disorder, where negative symptoms such as depression and avolition are similar, as well as positive symptoms like hallucinations
- it can lead to inconsistencies in diagnosis as different clinicians may diagnose different disorders, also reducing the reliability of diagnosis
14
Q
limitations of validity - gender bias
A
- the tendency for diagnostic criteria to be applied differently to males and females
- men seem to be far more likely to be diagnosed, perhaps because women are able to cope better with the symptoms
- Long and Powell (1988) randomly selected 290 male and female psychiatrists to read descriptions of patients’ behaviour and then diagnose them. when patients were described as males, 56% gave a diagnosis, compared to 20% when described as female
- this disparity may be due to gender bias in diagnosis, as no gender bias was found when the psychiatrist was female
- or, it may be due to valid differences in the incidence of schizophrenia between men and women, e.g. Cotton et al. (2009) suggests the better interpersonal functioning of women may cause doctors to miss schizophrenia diagnosis in women
- however, Kulkarni et al. (2001) found that administration of oestrogen reduces schizophrenia symptoms, suggesting biological differences may partly explain gender differences in schizophrenia
15
Q
limitations of validity - culture bias
A
- the tendency to over-diagnose members of other cultures as suffering from schizophrenia
- several studies have found that people of Afro-Caribbean descent living in Britain are much more likely than white people to be diagnosed as schizophrenic, and are also more likely to be confined in secure hospitals than white schizophrenics
- e.g. Cochrane (1977) found that rates of schizophrenia among Afro-Caribbeans living in the Caribbean are roughly the same as white people in Britain, suggesting either;
- an invalid diagnosis; Afro-Caribbean people in Britain are being over-diagnosed or the people in the Caribbean are being under-diagnosed
- a valid diagnosis; the diagnosis reflects a valid difference in schizophrenia rates and so environmental stressors in Britain, e.g. poverty and racism, are contributing to higher levels of schizophrenia in such cultural groups
- this suggests higher diagnosis rates are due to a cultural bias, rather than a genetic vulnerability
16
Q
biological explanations for schizophrenia
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- sees schizophrenia as determined by biological factors, including genetics, abnormal dopamine functioning, and neural correlates
- although causes of schizophrenia aren’t fully understood, research indicates that biological factors do play a role in the development of the disorder
17
Q
genetics
A
- sees schizophrenia as transmitted through genes passed onto individuals from their families
- Gottesman (1991) conducted a large-scale family study and found a strong relationship between the degree of genetic similarity and shared risk of schizophrenia - e.g. 48% concordance rate in MZ twins compared to 17% in DZ twins
- it’s believed that several genes are involved in increasing an vulnerability to developing schizophrenia, rather than one single gene - Ripke et al. (2014) found 108 genetic variations correlated with schizophrenia in a study of over 37,000 patients
18
Q
genetics - strengths
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- Kety and Ingraham (1992) found that prevalence rates of schizophrenia were 10x higher among genetic than adoptive relatives of schizophrenics, suggesting genetics play a greater role than environmental factors
19
Q
genetics limitations
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- methodological issues; family studies fail to consider the contribution of shared environmental influences on the development of the disorder, i.e. by living in the same house, and it may also be argued that MZ twins are treated more similarly than DZ twins, causing their concordance rate to be higher in Gottesman’s study
- concordance rates in MZ twins would be 100% if it was entirely genetic, but it’s not, suggesting environmental factors do play a role
20
Q
neural correlates
A
- suggests that abnormalities within specific brain areas may be associated with development of schizophrenia
- by using scanning techniques such as fMRI, researchers can compare the brains of schizophrenics and non-schizophrenics to identify differences in brain structures that may be linked to the disorder
21
Q
neural correlates - strengths
A
- several studies demonstrate correlations between neural structures and schizophrenia, e.g;
- Johnstone et al. (1976) found that enlarged ventricles are particularly linked with negative symptoms of the disorder, such as avolition and speech poverty
- Allen et al. (2007) found that reduced activity in the superior temporal gyrus and anterior cingulate gyrus is linked to positive symptoms of schizophrenia, such as auditory hallucinations
- Boos et al. (2012) found that schizophrenics had reduced grey matter and cortical thinning compared to their non-schizophrenic relatives
22
Q
neural correlates - limitations
A
- conflicting evidence; there are many people with enlarged ventricles who don’t have the disorder, and also many people with the disorder that don’t have enlarged ventricles
- it can be difficult to determine whether abnormal brain structures are a cause of schizophrenia, or an effect of it, i.e. correlation vs causation
- Ho et al. (2003) found evidence of brain damage worsening over time in patients as the severity of their symptoms also increased, suggesting brain damage increases in schizophrenics over time and may not be the initial cause of the disorder
23
Q
the dopamine hypothesis
A
- explains schizophrenia as a result of abnormal activity of the neurotransmitter dopamine
- it’s probable that genetic factors are linked to faulty dopaminergic systems;
- the original dopamine hypothesis focused on the role of high levels / activity of dopamine in the subcortex, e.g. an excess of dopamine receptors in Broca’s area may be associated with speech poverty
- more recent versions of the dopamine hypothesis instead focus on low levels of dopamine in the prefrontal cortex, e.g. in the negative symptoms of schizophrenia
- so, both high and low levels of dopamine in different brain regions may be involved in schizophrenia