AO1

• Diathesis means vulnerability. Stress refers to the negative experiences that trigger the vulnerability. Diathesis stress model says that both vulnerability and trigger are needed to develop schizophrenia. They individually may not create schizophrenia. It is the interaction that is key.
• Meehl's model states that diathesis is genetic. In Meehl's model it was entirely the result of a single schizogene. Meehl argued that someone without this gene should never develop schizophrenia, no matter how much stress they are exposed to. But a person who does have the schizogene is vulnerable to the effects of chronic stress, especially a schizophrenic mother. The schizogene is necessary but not sufficient for development of schizophrenia.
• The modern understanding of diathesis is that it is not due to a single schizogene. Ripke et al. suggested that many genes increase the vulnerability. Diathesis doesn't have to be genetic. Early psychological trauma could also affect brain development. For example, child abuse affects the hypothalamic pituitary adrenal system, making a child vulnerable to stress.
• The modern understanding of stress includes anything that risks triggering a schizophrenia. Houston et al said it can be psychological like parenting or biological like cannabis abuse. Cannabis abuse can increase the risk of schizophrenia up to 7 times depending on dose, probably because it interferes with the dopamine system. However, most people do not develop schizophrenia after smoking cannabis because they lack the requisite vulnerability.
• To treat schizophrenia, according to the interactionist approach, you will use antipsychotic drugs in combination with CBT. It is possible to believe in biological causes and still use CBT for psychological symptoms. However, this needs the interactionist model.
• It is not possible to adopt a purely biological approach, tell a patient that a conditional is solely biological, and then give them CBT as well. This was said by Turkington et al.

  In the UK, it is standard to treat patients with a combination of CBT and antipsychotics.

  In the US, there is a conflict between psychological and biological models of schizophrenia, leading to slower adoption of the interactionist approach.