Diathesis (vulnerability) was completely genetic - only one schizogene triggered by 'schizophregenic mother'
Led to development of 'schizotypic personality' which was vulnerable to stress
Without the schizogene no amount of stress could lead to Sz
Weaknesses
Oversimplistic - Sz is polygenic, so multiple genes increase vulnerability
Stress comes in many forms, not just dysfunctional parenting
Sz patients who suffer trauma, e.g. childhood abuse, can lead their brain to develop abnormally, meaning that stress becomes diathesis
One study - Houston - found that childhood sexual trauma was a vulnerability whilst cannabis was a trigger
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Modern Understanding of Diathesis & Stress
Diathesis
There is no single schizogene - Sz is polygenic
Include a range of factors beyond genetic, e.g. psychological trauma, so trauma becomes diathesis rather than stress
Early childhood trauma affects development of brain - hypothalamic pituitary gland (HPA) system can become overactive, making it more vulnerable to stress
Stress
Modern definition of stress in relation to diathesis-stress model is anything that increases the risk of developing Sz, not just dysfunctional parenting
Research into factors causing Sz is largely concerned with cannabis
Cannabis is a stressor - increases risk of Sz by up to 7 times as it interferes with dopamine
However most people do not develop Sz after smoking cannabis so there must be other factors
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Evidence for the Role of Vulnerability & Triggers
Tienari
Children adopted from 19,000 Finnish mothers with Sz were followed up
Adoptive parents assessed for parenting style
Rates of children with Sz compared to control group with no genetic vulnerability to Sz
Parenting style with high levels of criticism and conflict, and low levels of empathy was implicated in development of Sz for those with high genetic risk, but not those in the control group
Suggests that both genetic vulnerability and family-related stress are important in the development of Sz
Genetically vulnerable children are more sensitive to parenting style
Strong support for adopting an interactionist approach to Sz
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Treatment According to Interactionist Approach & E
Both biological and psychological factors are acknowledge so both biological and psychological treatments apply
Combination of antipsychotics (biological) and CBT (psychological)
Turkington - it is possible to believe biological causes of Sz and use CBT to relieve symptoms but this still requires the interactionist model
Increasingly common in Britain to be treated with a combination of biological and psychological methods
Unlikely to be treated for Sz by just psychological therapies
Strengths
Reseach support for combination therapies rather than just medication
Tarrier - Ps randomly allocated (increases internal validity) to either medication+CBT, medication+supportive counselling or control group (medication only)
Ps in combination groups showed lower symptom levels than control group but no difference in hospital readmission
Superior treatment outcomes shows clear practical advantage to using interactionist therapies, therefore highlights importance of interactionist approach
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