Schizophrenia: topic 9 ‘the interactionist approach to explaining and treating SZ, diathesis-stress model’

Question 1

What is the diathesis stress model?

Answer 1

• the diathesis stress model sees schizophrenia as the result of an interaction between biological (innate) and environmental (external) influences
• family studies suggest that people have variant levels of inherited genetic vulnerability to schizophrenia, from very high to very low
• however, whether or not the person develops schizophrenia is partly determined by this internal vulnerability and also partly by the amount and level of stresses experience over their lifetime

Question 2

Where does evidence come from to suggest that genes play a key role in the development of schizophrenia?

Answer 2

• twin studies

Question 3

diathesis

Answer 3

• MZ twins who share 100% of the same jeans are at a greater risk of developing schizophrenia than a sibling or DZ twin
• In about 50% of our identical twins in which one has the disorder, the other does not
• This suggests that environmental factors must also play a role in determining whether a biological vulnerability for schizophrenia actually develops into the disorder

Question 4

stress

Answer 4

• the sort of stressful life events that trigger schizophrenia take a variety of forms such as childhood drama
• varse found that children who experienced severe trauma before the age of 16 were 3x as likely to develop schizophrenia in later life compared to the general population
• it has also been suggested that living in an urban environment also increases the risk of developing SZ, possibly as a result of the stressful living conditions of densely populated environments
• breakdown of a relationship and academic pressure could also trigger schizophrenia

Question 5

what is the interactionist approach?

Answer 5

• The interactionist model of SZ acknowledges both biological and psychological factors in schizophrenia
• It is therefore compatible with both biological and psychological treatments

Question 6

What would the interactionist approach suggest for treatment?

Answer 6

• The model would recommend combining antipsychotic medication and psychological therapies (most commonly CBT)

Question 7

strengths of the diathesis-stress model

Answer 7

P - evidence to support the dual role of vulnerability and stress in the development of schizophrenia comes from tienari
E - assessed adopted children whose biological mother was a sufferer of schizophrenia compared to a control group of adoptee without any genetic risk
E - found that parent in style characterised as high levels of criticism and conflict, with low levels of empathy was implicated in the development of the disorder, but only for the children with high genetic risk and not in the control group
L - this suggests that both genetic vulnerability and family related stress are important in the development of schizophrenia, and that poor parenting could be a possible source of stress

P - support for the effectiveness of combinations of treatment from tarrier
E - phone number after patients were randomly allocated to a medication + CBTp group, or medication + supportive counselling group, or control group, patients in the two combined treatments group showed lower levels of symptoms than those in the control group
E - studies like this show that there is a clear practical advantage to adopting an interactionist approach to achieving superior treatment outcomes for patients
L - therefore, the interactionist approach can be praised for taking a holistic view to explaining and treating schizophrenia

Question 8

limitations of the diathesis-stress model

Answer 8

P - diathesis may not be exclusively genetic
E - many have argued that the increased risk of SZ that was originally thought to always come from genetics, may also result from brain damage caused by environmental factors
E - for example, verdoux estimated that risk of SZ for individuals who experienced birth complications are 4x greeter than those who experience no such complications, meaning birth complications may produce a vulnerability
L - this suggests that the diathesis is not always due to genetics, and diathesis can’t be due to damage to brain structure which can be caused by environmental factors

P - stress may not be exclusively environmental
E - although in the original diathesis stress model of SZ, stress was seen as psychological in nature, more modern versions suggest biological factors like illness and drug use may trigger SZ
E - for example, cannabis is seen as a key stressor because it increases the risk of SZ by up to 7x according to the dose, probably because cannabis interferes with the dopamine system
L - this suggests that biological factors can also be a source of stress for the trigger of diathesis of schizophrenia

P - we do not know exactly how diathesis and stress work
E/E - well there is strong evidence to suggest that some sort of underlying vulnerability coupled with stress can lead to schizophrenia, we do not yet fully understand the mechanisms by which the symptoms of schizophrenia appear, and how both vulnerability and stress interact to produce them
L - this suggests that the interactionist explanation of schizophrenia is incomplete and limited in its explanation of how schizophrenia develops