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Schizophrenia - The Interactionist Approach (Evaluation (Evidence for role…
Schizophrenia - The Interactionist Approach
Definitions
Interactionist Approach
- approach to explain schizophrenia that acknowledges a range of factors, biological (genetic vulnerability and neurochemical / neurological abnormalities) and psychological (stress, e.g. from life events / daily hassles + poor quality interactions with family)
Diathesis-stress model
- explains schizophrenia is the result of both underlying vulnerability (diathesis) and a stress trigger, both of which are necessary for the onset of schizophrenia. Both genes and trauma are seen as diatheses, and stress can be biological or psychological.
Explaining the approach: diathesis-stress
Modern understanding of diathesis
- many genes each appear to increase vulnerability slightly (no single 'schizogene'). Also, there are a range of factors beyond the genetic, e.g. psychological trauma, where trauma is the diathesis not the stressor. Read proposed early trauma alters the developing brain. Early and severe enough trauma (e.g. child abuse) can have massive effects on brain development. Example: hypothalamic-pituitary-adrenal (HPA) system can become overactive, meaning greater vulnerability to later stress.
Modern understanding of stress
- includes anything that risks triggering schizophrenia, not just psychological stress (e.g. from parenting). Cannabis is a stressor because it increases onset risk by up to seven times depending on dose. Probably due to cannabis interfering with dopamine system. However onset from cannabis is uncommon so it seems there must be one or more vulnerability factors.
Meehl's model (original model)
- diathesis was entirely genetic, resulting from single 'schizogene'. Leads to development of biologically-based 'schizotypic personality', which includes sensitivity to stress. If a person does not have the gene, no amount of stress would lead to schizophrenia. If you are a carrier, chronic stress in childhood and adolescence (e.g. schizophrenogenic mother) could result in onset of the condition.
Treatment according to the model
- due to nature of the model, it is compatible with both biological and psychological treatments. Associated with combining antipsychotic medication with psychological therapies like CBT.
Douglas Turkington et al
- possible to believe in biological causes but still practice CBT to relieve psychological symptoms. Requires adopting interactionist model; not possible to adopt a purely biological approach and ignore significance of psychological symptoms and still treat with CBT.
In Britain it is
increasingly standard practise to treat patients with combination of drugs and CBT
, but in USA there is still conflict between biological and psychological models of schizophrenia, leading to a slower adoption of the interactionist approach. Medication without accompanying psychological treatment is more common there.
Unusual to treat schizophrenia with psychological treatments alone;
treatments like CBT and token economy systems are usually carried out on patients taking antipsychotics aswell
.
Evaluation
Evidence for role of vulnerability and stress triggers - Tienari et al.
Parenting style with high criticism and conflict and low empathy was implicated in development of schizophrenia
, but only in children with high genetic risk
(not in control group).
Strong support for interactionist approach
-
genetic vulnerability and family-related stress combine
in schizophrenia development.
Studied
children adopted away from schizophrenic mothers
. Adoptive parents'
parenting styles compared to control group
of adoptees with no genetic risk.
Useful approach for treatment - Tarrier at al.
Patients in
combination groups showed lower symptom levels than those in control group
, despite no difference in hospital readmission rates.
Clear practical advantage in adopting approach
- superior treatment outcomes.
Randomly allocated 315 patients to three groups
(medication + CBT / medication + supportive counselling / control group)
Original diathesis-stress model is too simplistic
However,
multiple genes increase vulnerability
(no single 'schizogene') and
stress can also include biological factors
(not just parenting style).
Support:
Houston et al
. found
childhood sexual trauma was a diathesis
and
cannabis use was a trigger
.
Old
idea of diathesis as biological and stress as psychological is overly simplistic
.
Original model
suggested that there was
one single 'schizogene'
that caused vulnerability, and
stress was the result of dysfunctional parenting
.
We don't know exactly how diathesis and stress work
But we do not understand the mechanisms by which symptoms of schizophrenia appear and how vulnerability and stress produce them.
This does not undermine support of the approach, but it does mean we have an incomplete understanding of the actual mechanism.
There is strong evidence that underlying vulnerability coupled with stress can lead to schizophrenia.