Biological Explanations of SZ Flashcards
What are the 4 AO1 points?
Family Studies
Twin Studies
Adoption Studies
The Dopamine Hypothesis
What are the the 5 AO2 points?
Family Studies Twin Studies Methodological Flaws Post Mortem Studies An Evolutionary Perspective
What do family studies investigate?
Whether SZ relatives are more likely to be affective by non relative, as higher proportion of shared genes
What has been established from family studies?
SZ more common among biological relatives of SZc
Family Studies: the closer the degree of genetic relation…
The higher the risk of SZ dvlpt
What have family studies concordance rates shown?
46% with 2 SZ parents
13% with 1 SZ parent
9% SZ sibling
What does concordance rates in family studies demonstrate?
Lend support to theory of genetic basis
Twin Studies..If MZ twins (share 100% of their genes)
Are concordant in a trait such as SZ compared to DZ twins, there must be a genetic basis
Twin studies. If MZ twins are concordant in SZ then?
Nurture can be discounted to some extent, as twins would share same environment
What did Joseph find in relation to twin studies?
Identical twins - 40%
Non I twins - 7.4%
Strong argument for genetic factors
In adoption studies, why are genetically related individuals reared apart used?
To disentangle environmental influences from genetics (compared to control group of adoptees with non SZ parents)
What did Tineari find?
11/164 children whose mothers have SZ
4/197 of control group with no SZ genes
What do Tinearis findings show?
Supports the role of genes in influencing onset of SZ
What is a flaw of Twin Studies?
Assumed that high concordance rates are a product of greater genetic similarity rather than environmental similarity - CRITICAL
What might higher concordance rates be due to rather than genetic similarity?
Identical twins being more inclined to similar treatment/viewed as one person so sharing the same environment (Joseph)
How is the idea that it might be environment rather than genes reinforced?
40% concordance not 100%? Environment must play a large mitigating role…
A third and final reason why higher concordance rates might be due to environment rather than simply genetic vulnerability?
- Diathesis Stress Model, g/e interaction
- Environmental triggers and stressors might activate genetic vulnerability for SZ
What is a problem with adoption studies?
Assumption that SZ children not selectively placed
What did Joseph claim regarding placement of SZ children?
- Parents informed of genetic vulnerability
- Might wonder what sort of parents would continue with adoption
- Skewing results
What is a methodological issue regarding SZ adoption studies?
- SZ spectrum broadened to accomodate sz spectrum disorders
What would might have happened if SZ definition wasnt broadened for adoption studies?
Same statistical would not have been found
What is the Dopamine Hypothesis?
- Neurons transmitting dopamine fires too easily/often
- Strangely high numbers of D receptors on receiving neutrons, so more dopamine binding/neuron firing
What do D neurons play a role in?
Guiding attention, so disturbances may well lead to problems relating to attention such as SZ
How do AP’s strengthen the case of Dopamine playing a role in SZ?
Block dopamine activity and in turn eliminate symptoms such as hallucinations
What is a major problem with the Dopamine hypothesis?
-Dopamine blocking drugs can actually increase D levels
Why can dopamine blocking drugs increase D levels?
Neutrons struggle to compensate for D deficiency
What do post mortem studies show?
- Those with increased D levels
- Many of which had received APs shortly before death
Why might Sz be an ancestral/evolutinary disorder?
Originated in ancestral humans
Australian Aborigines became isolated from rest of human kind yet SZ still observed
Why might SZ be adaptive?
- Help split tribal communities to prevent uproar
- Charasmatic ppl facilitate the splitting of groups, bizarre beliefs etc help influence unhappy members in leaving
