Biological explanations - genetics

Question 1

What is the genetic theory?

Answer 1

We inherit 50% of our genes from each parent, and these build our bodies, especially the brain which is the source of all mental states

Question 2

How could schizophrenia have a genetic basis?

Answer 2

It is a disorder of the mental state, which is affected by the brain and genes so could be heritable

Question 3

What was the original belief about the cause of schizophrenia?

Answer 3

It could be entirely genetic

Question 4

What is the modern believe about the cause of schizophrenia?

Answer 4

Most see genes as the diathesis in the diathesis-stress model

Question 5

What have family studies found about schizophrenia?

Answer 5

That schizophrenia runs in families to some extent

Question 6

What have twin studies and adoption studies tested?

Answer 6

The effect of genes

Question 7

How can a genetic component of schizophrenia be found?

Answer 7

By identifying specific candidate genes and what they do

Question 8

What was the original belief about genes and schizophrenia?

Answer 8

There could be a gene for schizophrenia

Question 9

What is the modern belief about genes and schizophrenia?

Answer 9

Schizophrenia is polygenic so it involves multiple genes

Question 10

How do genes link to the dopamine hypothesis?

Answer 10

Many of the candidate genes for schizophrenia code for the neurotransmitter dopamine

Question 11

How do we test for candidate genes?

Answer 11

Studies of molecular genetics

Question 12

What is research evidence for the genetic explanation of schizophrenia?

Answer 12

Gottesman’s meta-analysis

Question 13

What were Gottesman’s innings?

Answer 13

The concordance rate for DZs was 48% and 17% for MZs

Question 14

What were the conclusions of Gottesman’s meta analysis?

Answer 14

There was a large difference, so there is a moderate to strong effect of genes

Question 15

What is the logic of twin studies?

Answer 15

Siblings have 50% in common and different ages, so environment is similar but different, whereas MZs have 100% of genes in common, but DZs have 50%, do DV is relatedness and is a natural experiment

Question 16

What do twins studies control?

Answer 16

Environment, as both twin are raised together at the same time so are very similar

Question 17

What is a strength of twin studies?

Answer 17

They enhance the scientific credibility of genetic theory as evidence is better is more controlled and there is more of it

Question 18

What are the strengths of Gottesman’s meta-analysis?

Answer 18

Shows a pattern of data across studies, merging data reduces the effect of variation, estimates of concordance rates are likely to be accurate and enhances scientific credibility of genetic theory

Question 19

What are the limitations of twin studies?

Answer 19

MZs are treated more similarly than DZs, twin studies may exaggerate influence of genetics and reduces scientific credibility of genetic theory

Question 20

What is research evidence for adoption?

Answer 20

Tienari’s adoption study

Question 21

What were Tienari’s findings?

Answer 21

Concordance rate between biological mothers with sz and their adopted away offspring was 7%, and concordance rate of adopted away offspring without sz was 1.5%

Question 22

What were the conclusions of Tienari’s study?

Answer 22

There was a reasonable size difference so moderate effect

Question 23

What are strengths of adoption studies over twin studies?

Answer 23

There is full separation of genetic and environmental influences so is strong evidence, enhancing scientific credibility of genetic theory

Question 24

What are strengths of twin studies and adoption studies?

Answer 24

Findings have been replicated many times, so triangulated evidence from different types of research, enhancing scientific credibility of genetic theory

Question 25

What is the interactionist approach to explains schizophrenia?

Answer 25

The diathesis stress model

Question 26

What is the issue with twin and adoption studies evidence?

Answer 26

The concordance rates are too low for it to be entirely genetic

Question 27

What is the issue with the genetic theory?

Answer 27

It is incomplete otherwise concordance would be much higher so no single factor explains schizophrenia, such as genes and family stressors

Question 28

What the issue with the environmental explanation?

Answer 28

It can’t be complete or rates of schizophrenia would be much higher as stressors are common

Question 29

How do stressors affect schizophrenia?

Answer 29

They only trigger schizophrenia in already genetically vulnerable people, genes don’t lead to schizophrenia in those with low stressors

Question 30

What is the polygenic model?

Answer 30

Schizophrenia is due to multiple genes and is a better alternative to the single gene view

Question 31

What is evidence for the polygenic model?

Answer 31

Ripke’s meta-analysis

Question 32

What were the findings of Ripke’s meta-analysis?

Answer 32

108 genes link to SZ, often including genes linked to dopamine reduction, with only each risk gene increasing the risk by a small amount

Question 33

What were the findings of Ripke’s meta-analysis?

Answer 33

108 genes link to SZ, often including genes linked to dopamine reduction, with only each risk gene increasing the risk by a small amount