Interactionist Approach Flashcards
what is an interactionist approach to schizophrenia?
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the diathesis stress model
what is the diathesis stress model?
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proposes that schizophrenia is the result of an interaction between biological and environmental influences
it therefore believes that schizophrenia is caused by a combination of psychological, environmental and biological influences
the symptoms of schizophrenia are triggered or made worse when significant stressors in the person’s life are combined with a biological vulnerability to schizophrenia known as the diathesis
this model may explain why not all people who have a genetic vulnerability to schizophrenia go on to develop the disorder
family studies suggest that people have varying levels of inherited genetic vulnerability to schizophrenia, but whether or not a person develops the disorder is partly determined by this vulnerability and partly by the stresses they experience over their lifetime
explain diathesis
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schizophrenia has a genetic component in terms of vulnerability to the disorder
twin studies support the existence of genetic influences in schizophrenia as they have found that the identical twin of someone with schizophrenia has a greater chance of developing the disorder than a sibling or fraternal twin — as identical twins are more genetically similar, it must be genetics that causes this increased risk
Tienari et al (2004) also found that adoptive relatives do not share the increased risk of developing schizophrenia that biological relatives have
however, in about 50% of identical twins in which one twin is diagnosed with schizophrenia, the other never meets the diagnostic criteria for the disorder
this discordance among identical twins indicates that environmental factors must also play a role in determining whether a biological vulnerability for schizophrenia actually develops into the disorder
explain the role of stress in developing schizophrenia
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stressful life events that can trigger schizophrenia take a variety of forms, such as childhood trauma or the stresses associated with living in a highly urbanised environment
stresses: childhood trauma
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Varese et al (2012) found that children who experienced severe trauma before the age of 16 were three times as likely to develop schizophrenia in later life compared to the general population
there was a relationship between the level of trauma and the likelihood of developing schizophrenia, with those severely traumatised as children being at greater risk
stresses: urbanised environments
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research also suggests that a high level of urbanisation is associated with an increased risk of developing a range of different psychoses, including schizophrenia
a meta analysis by Vassos et al (2012) found that the risk for schizophrenia in the most urban environments was estimated to be 2.37 times higher than in the most rural environments
the reason why urbanisation and schizophrenia are linked is not clear, although it is possible that the more adverse living conditions of densely populated urban environments may be a contributory factor
many people live in densely populated urban areas, but only a tiny minority of these will develop schizophrenia — the relationship between urban stress and schizophrenia is conditional on other factors such as a pre existing genetic vulnerability for the disorder
the additive nature of diathesis and stress
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there are several ways in which a combination of diathesis and stress can lead to the onset of schizophrenia
for example, relatively minor stressors may lead to the onset of the disorder for an individual who is highly vulnerable
or a major stressful event might cause the onset of the disorder in a person low in vulnerability
whatever the combination, this idea presupposes additivity — the diathesis and stress add together in some way to produce the disorder
key study: procedure
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Tienari et al (2004) reviewed hospital records for nearly 20,000 women admitted to Finnish psychiatric hospitals between 1960 and 1979
researchers identified those who had been diagnosed at least once with schizophrenic or paranoid psychoses
the list was checked to find mothers who had one or more of their offspring adopted away
these 145 adopted away offspring (the high risk group) were then compared with a sample of 158 adoptees without this genetic risk of developing schizophrenia (the low risk group)
both groups were independently assessed after a median interval of 12 years, with a follow up after 21 years
psychiatrists also assessed family functioning in the adoptive families using the OPAS — a scale that measures families on various aspects of functioning such as parent-offspring conflict, lack of empathy and insecurity
the interviewing psychiatrists did not know whether the biological mother was schizophrenic or not
key study: findings
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of the 303 adoptees, 14 had developed schizophrenia over the course of the study
of these 14, 11 were from the high risk group and had biological mothers who had been diagnosed with schizophrenia or a paranoid psychosis
the other 3 were from the low risk group
however, being reared in a ‘healthy’ adoptive family (families with low OPAS ratings) appeared to have a protective effect even for those with a high genetic risk for schizophrenia
high genetic risk adoptees reared in such families were significantly less likely to develop schizophrenia than high genetic risk adoptees reared in families with high OPAS ratings
adoptive family stress was a significant predictor of the development of schizophrenia in high genetic risk adoptees but not in low genetic risk adoptees (the control group)
x4 evaluation points
diatheses may not be exclusively genetic
real world applications
urban environments are not necessarily more stressful
research support
EVALUATION
diatheses may not be exclusively genetic
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most diathesis stress models emphasise vulnerability to schizophrenia in terms of genetic influences alone
these genetic influences are assumed to cause neurochemical abnormalities that result in an increased risk of schizophrenia
however, this increased risk can also result from brain damage caused by environmental factors
for example, individuals may also develop a vulnerability to schizophrenia if they experience birth complications
Verdoux et al (1998) estimated that the risk of developing schizophrenia later in life for individuals who have experienced obstetric complications at birth, such as prolonged labour which can cause oxygen deprivation, is four times greater than those who experience no such complications
however, as the diathesis stress model does not seem to consider this, it may be limited in its ability to explain schizophrenia
EVALUATION
real world applications
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the diathesis stress model has implications for the treatment of schizophrenia
if the onset of schizophrenia is a result of the additive effects of genetic vulnerability and environmental stress, then this has implications for the treatment of the disorder
although genetic vulnerability is difficult to control, certain other important factors known to interact with genetic vulnerability can be addressed using knowledge gained from the diathesis stress model
for example, Borglum et al (2014) found that women infected with the cytomegalovirus during pregnancy were more likely to have a child who developed schizophrenia, but only if both mother and child carried a particular gene defect
this suggests that anti-viral medicine during pregnancy may prevent the onset of schizophrenia in the offspring of women known to have this gene defect
therefore, the diathesis stress model has important real world applications which increases its usefulness
EVALUATION
urban environments are not necessarily more stressful
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the Vassos et al study suggested that living in densely populated urban environments was a significant stress factor for schizophrenia
however, not all research has agreed with this finding
for example, Romans-Clarkson et al (1990) found no urban-rural differences in mental health among women in New Zealand
other studies, although finding evidence of urban-rural differences, also noted that these differences disappeared after adjusting for the socio-economic differences for the two groups
this suggests that, although social adversity may well be a significant trigger for the onset of schizophrenia, claims that social adversity and urbanisation are synonymous is likely to be an oversimplification
research is inconclusive about whether living in an urban environment is a significant stressor in the onset of schizophrenia, challenging the element of the diathesis stress model which claims that it is
EVALUATION
research support
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Tienari et al (2004) reviewed hospital records for nearly 20,000 women admitted to Finnish psychiatric hospitals between 1960 and 1979
researchers identified those schizophrenic and found women who had one or more of their offspring adopted away
145 adopted away offspring (the high risk group) were then compared with a sample of 158 adoptees without this genetic risk of developing schizophrenia (the low risk group)
they found that of the 303 adoptees, 14 had developed schizophrenia over the course of the study
of these 14, 11 were from the high risk group and had biological mothers who had been diagnosed with schizophrenia or a paranoid psychosis
however, high genetic risk adoptees reared in healthy families with low OPAS ratings were significantly less likely to develop schizophrenia than high genetic risk adoptees reared in families with high OPAS ratings
adoptive family stress was a significant predictor of the development of schizophrenia in high genetic risk adoptees but not in low genetic risk adoptees (the control group)
this suggests that there is both a genetic and environmental influence in schizophrenia, which supports the diathesis stress model and increases its ability to explain schizophrenia
