The interactionist approach - The diathesis - stress model

What is it?

Model sees SZ as a r of interaction of bio + environmental influences

Biological influences

Genetic risk factors

Environmental influences

• SZ mother, family d and drugs

E.g. of bio influences

• Fam/twin studies suggest that ppl have varying levels of gen v to sz

Person develops SZ is due to …

Levels of stress over their lifetime

What is SE for SZ has gen conponent in terms of vulnerability

Tienari etval 2004 - increased risk of SZ from bio rather than social factors

However Joseph (2004) found concordance rates for MZ twins were only 40%

Why do Joseph’s findings using MZ twins being only 40% indicate

MZ have 100% same DNA

60% is due to other factors - interactionist approach

Discordance e factors must play a part whether a bio vulnerability for disorder eventually manifests

What are environmental stressors?

• Childhood trauma , stress of highly urbanised living

What did Varse et al find

• Children experienced sev trauma under age of 16 were 3x more likely to = SZ later life compared gen pop

What was the conclusion Varse et al made?

• SZ was positively correlated to level of trauma

• More highly traumatic exps you have = more likely to develop SZ

What is interactionist approach

argues that several levels of explanation are necessary to explain a particular behaviour, ranging from lower (biological) to higher levels (social and cultural).

Why is original diathesis stress model said to be over-sim

• Suggested Single gene + SZ parenting styles

• See Harrington 2012 - little evidence that parental characteristics influence SZ development

• Gen v polygenic

• No single diathesis or stress source

What is SE for interactionist explanations of SZ

Tienari et al 2004

Ripke et al - support for it being polygenic combined prev data from genome studies and found 108 sep genes were linked to increased of SZ

Gene of SZ

COMT

SE for effectiveness of interactionist treatment

• Anderson et al

• Tarrier et al (2004)

• Token e + drugs targeting diff symptoms (Upper + Newton)

Anderson et al

Found a relapse rate of almost 40% when patients had drugs only

Compared to 20% when fam therapy or social skills training were used + relapse rate was less than 5% when both were used together with medication