Discuss the interactionist approach for schizophrenia - 16 marks
The interactionist approach is a way of explaining the development of behaviour through many
factors, including biological and psychological ones. These factors interact and cannot be studied in
isolation and separately. The diathesis stress model is a way to present an interactionist approach.
The diathesis-stress model suggests that someone can have an underlying genetic vulnerability or
predisposition to schizophrenia, but there needs to be an environmental trigger such as trauma or
abuse to cause the onset or development of schizophrenia. In early versions of the diathesis-stress
model, vulnerability was genetic, and triggers were psychological. Nowdays, both genes and trauma
are seen as diatheses, and stress can be psychological or biological in nature.
Meehl’s original diathesis-stress model (1962) said the diathesis was entirely genetic, due to single
“schizogene”. This led to idea of a biologically based schizotypic personality, one characteristic of
which is sensitivity to stress. According to Meehl, if a person does not have the schizogene then no
amount of stress would lead to schizophrenia.
Modern understanding of the diathesis makes it clear that many genes each appear to increase
genetic vulnerability only slightly, meaning there is no single “schizogene” (Ripke et al). Modern
views suggest a range of factors can trigger the development of schizophrenia beyond genetic
factors, such as trauma (Ingram and Luxton 2005). Here, trauma becomes the diathesis rather than
the stressor. Furthermore, Read et al (2001) propped a neurodevelopmental model in which early
trauma alters the developing brain. For example, the hypothalamic-pituitary-adrenal system can
become overactive, making a person much more vulnerable to later stress. Also, genes are
aetiologcally heterogeneous which means they play out differently in different people.
Modern understanding of the stress is different to the original diathesis-stress model, where stress
was seen as psychological in nature. The modern definition of the stress includes anything that risks
triggering schizophrenia (Houston et al 2008). Contemporary research by Di Forti et al has concerned
the risk of schizophrenia with use of THC rich cannabis. They found that participants that smoked
cannabis were x7 more likely to develop schizophrenia than those who didn’t. This may be because
cannabis interferes with dopamine system. However, the majority of people who smoke cannabis do
not develop schizophrenia because they lack the requisite vulnerability factors.
As the interactionist model acknowledges both biological and psychological factors it is compatible
with both biological and psychological treatments. The interactionist approach combines
antipsychotic medication and psychological therapies, most commonly CBT. Turkington et al (2006)
point that it is perfectly possible to believe in biological causes of schizophrenia and still practice CBT
to relieve psychological symptoms, however this involves adopting an interactionist model. In US
there is more of a history of conflict between psychological and biological models, so this has led to
slower adoption of interactionist approach. Thus, medication without accompanying psychological
treatment is more common in US than UK.
One strength of the interactionist approach to schizophrenia is evidence supporting the role of both
vulnerability and triggers. In a large-scale study, Tienari et al (2004) investigated the impact of both
genetic vulnerability and a psychological trigger (dysfunctional thinking). The study followed 19,000
Finnish children whose biological mothers has been diagnosed with schizophrenia. In adulthood this
high genetic risk group were compared to a control group of adoptees without a family history of
schizophrenia. Adoptive patients had been assessed for child-rearing style and it was found that high
levels of criticism, hostility and low levels of empathy were strongly associated with the
development of schizophrenia, but only in the high genetic risk group. This is a strength of the
The interactionist approach is a way of explaining the development of behaviour through many
factors, including biological and psychological ones. These factors interact and cannot be studied in
isolation and separately. The diathesis stress model is a way to present an interactionist approach.
The diathesis-stress model suggests that someone can have an underlying genetic vulnerability or
predisposition to schizophrenia, but there needs to be an environmental trigger such as trauma or
abuse to cause the onset or development of schizophrenia. In early versions of the diathesis-stress
model, vulnerability was genetic, and triggers were psychological. Nowdays, both genes and trauma
are seen as diatheses, and stress can be psychological or biological in nature.
Meehl’s original diathesis-stress model (1962) said the diathesis was entirely genetic, due to single
“schizogene”. This led to idea of a biologically based schizotypic personality, one characteristic of
which is sensitivity to stress. According to Meehl, if a person does not have the schizogene then no
amount of stress would lead to schizophrenia.
Modern understanding of the diathesis makes it clear that many genes each appear to increase
genetic vulnerability only slightly, meaning there is no single “schizogene” (Ripke et al). Modern
views suggest a range of factors can trigger the development of schizophrenia beyond genetic
factors, such as trauma (Ingram and Luxton 2005). Here, trauma becomes the diathesis rather than
the stressor. Furthermore, Read et al (2001) propped a neurodevelopmental model in which early
trauma alters the developing brain. For example, the hypothalamic-pituitary-adrenal system can
become overactive, making a person much more vulnerable to later stress. Also, genes are
aetiologcally heterogeneous which means they play out differently in different people.
Modern understanding of the stress is different to the original diathesis-stress model, where stress
was seen as psychological in nature. The modern definition of the stress includes anything that risks
triggering schizophrenia (Houston et al 2008). Contemporary research by Di Forti et al has concerned
the risk of schizophrenia with use of THC rich cannabis. They found that participants that smoked
cannabis were x7 more likely to develop schizophrenia than those who didn’t. This may be because
cannabis interferes with dopamine system. However, the majority of people who smoke cannabis do
not develop schizophrenia because they lack the requisite vulnerability factors.
As the interactionist model acknowledges both biological and psychological factors it is compatible
with both biological and psychological treatments. The interactionist approach combines
antipsychotic medication and psychological therapies, most commonly CBT. Turkington et al (2006)
point that it is perfectly possible to believe in biological causes of schizophrenia and still practice CBT
to relieve psychological symptoms, however this involves adopting an interactionist model. In US
there is more of a history of conflict between psychological and biological models, so this has led to
slower adoption of interactionist approach. Thus, medication without accompanying psychological
treatment is more common in US than UK.
One strength of the interactionist approach to schizophrenia is evidence supporting the role of both
vulnerability and triggers. In a large-scale study, Tienari et al (2004) investigated the impact of both
genetic vulnerability and a psychological trigger (dysfunctional thinking). The study followed 19,000
Finnish children whose biological mothers has been diagnosed with schizophrenia. In adulthood this
high genetic risk group were compared to a control group of adoptees without a family history of
schizophrenia. Adoptive patients had been assessed for child-rearing style and it was found that high
levels of criticism, hostility and low levels of empathy were strongly associated with the
development of schizophrenia, but only in the high genetic risk group. This is a strength of the
