diathesis stress model - interactionist approach to schizophrenia

diathesis

vulnerability

stress

negative experience which acts as the trigger

meehl’s diathesis stress model (outdated)

diathesis is genetic (singular ‘schizogene’), stress is always neg psychological experience in childhood/adolescence e.g. parenting (usually schizophrenogenic mother), if a person does not have the ‘schizogene’ then no amount of stress would cause sz

modern diathesis-stress model - diathesis

no singular gene (‘schizogene’ doesn’t exist) - polygenic condition (ripke 2014), diathesis may be psychological trauma which then creates physiological vulnerability (ingram & luxton 2005), early trauma e.g. child abuse affects developing brain (read 2001), the HPA (hypothalamic -pituitary-adrenal) system can become overactive and this makes a person more vulnerable to later stress

modern diathesis-stress model - stress

originally seen as psychological (parenting), now recognition that stress can be anything which triggers sz (houston 2008) e.g. cannabis use increases risk of sz by up to 7x

research support for vulnerability and triggers - strength of diathesis stress model

tienari - large scale study, followed 19,000 finnish adoptees whose bio mothers had sz, high genetic risk group compared to control group of adoptees without family history of sz, adoptive parents assessed for child rearing style, found high levels of criticism + hostility and low levels of empathy strongly associated with sz development in high genetic risk group - combo of genetic risk and family stress can lead to sz

diathesis and stress are complex - limitation of meehl’s model, support for modern model

oversimplifies with schizogene and schizophrenogenic mother, houston - found childhood sexual abuse emerged as major influence on underlying vulnerability to sz and cannabis use as major trigger, multiple factors both biological and psychological affect diathesis and stress as stated in modern model

real world application - strength of diathesis stress model

acknowledges both bio and psych factors contribute to sz so compatible with a combination of bio and psych therapies e.g. antipsychotics with CBT, tarrier - randomly allocated 315 ppts to medication+cbt, medication+counselling and control group with only medication, ppts in 2 combo groups showed lower symptoms after trial compared to control although no difference in hospital readmission - practical advantage in superior treatment outcomes

treatment-causation fallacy - limitation of diathesis stress model

jarvis and okami - cannot automatically assume success of combined therapies means interactionst explanations are correct, saying successful treatment for mental disorder justifies explanation is equivalent of saying that alcohol reduces shyness so shyness caused by lack of alcohol

urbanisation - further evaluative point

sz more commonly diagnosed in urban than rural areas, used to justify diathesis stress model as urban areas more stressful than rural so living in city acts as trigger, however, may be that sz more likely to be diagnosed in cities or that people with diathesis for sz tend to migrate to cities