biological explanations of schizophrenia (genetics and neural correlates)

Question 1

where does evidence for the role of genetics in schizophrenia

Answer 1

family, twin, adoption studies, candidate gene studies and gene mutation

Question 2

what % of their genes do monozygotic and dizygotic twins share

Answer 2

MZ 100%
DZ 50%

Question 3

who are first degree relatives

Answer 3

biological parents, siblings

share 50% of genes

Question 4

who are 3rd degree relatives

Answer 4

first cousins, great grandparents

Question 5

who are second degree relatives

Answer 5

biological grandparent, aunt, uncle, half-siblings

Question 6

what study gives evidence for the role of genetics in family, twin and adoption

Answer 6

gottesman

Question 7

The more genetic ….. a person carries, the …. likely they are to develop schizophrenia.

Answer 7

risk alleles
more likely

Question 8

According to the genetic explanation of schizophrenia, if some family members have schizophrenia, then it is ….. likely that you will develop schizophrenia.

This is because you may ….. a specific gene….. associated with schizophrenia.

Answer 8

more
inherit
allele

Question 9

if you inherit a gene allele that increases the likelihood of developing schizophrenia it doenst mean you will get it, what else may it depend on

Answer 9

other gene alleles you carry
environmental factors

Question 10

what does the genetic explanation say about the number of gene alleles responsible for increasing the risk

Answer 10

there are multiple not just one

Question 11

in twin studies, who is compared

Answer 11

researchers compare monozygotic and dizygotic twins

Question 12

in twin studies, a rate is calculated. what rate and what is it

Answer 12

concordance rare which is The percentage of twins that both share the same trait, given that at least one twin has the trait.

Question 13

For a particular trait, there might be a difference in concordance rates between monozygotic and dizygotic twins. What does this difference tell us about the influence that genetics has on this trait?

Answer 13

A BIG concordance rate shows that genetics has a BIG influence on the trait COMPARED to other factors.

Question 14

Gottesman & Shields twin study on schizophrenia found that there was a …..% concordance rate in MZ and a ….% concordance rate in DZ

Answer 14

mz= 74%
dz= 24%

Question 15

what does Gottesman & Shields twin study indicate about the development of schizophrenia

Answer 15

Schizophrenia is partially influenced by our genetics.

Question 16

Gottesman & Shields twin study: As the concordance rates for monozygotic twins was not ….% what can be said about schizophrenia development?

Answer 16

100%
Schizophrenia is not just caused by genetics.
Schizophrenia development is also influenced by the environment.

Question 17

What is one assumption that twin studies make?

Answer 17

The environment will have the same impact on phenotype for both monozygotic and dizygotic twins.

eg dressed the same, treated the same/mistaken for each other if (mz) may not happen so much if dz

Question 18

If monozygotic twins might also have a more similar environment than dizygotic twins, what does this mean for any differences in concordance rates between monozygotic and dizygotic twins?

Answer 18

they might be caused by environmental factors.
They might be caused by genetics.

Question 19

what is an issue that twin studies may have? over exaggerate…

Answer 19

Twin studies might over exaggerate the importance of genetics.

Question 20

example of how mz twins could have a more similar environment than dz twins

Answer 20

more likely to be both bullied at school so both get same stress which could contribute to high concordance rate

Question 21

a weakness of Gottesman and Shields’ study?

Answer 21

The study assumes that monozygotic twins and dizygotic twins have a similar amount of shared environment.

mz are more likely to be treated the same than dz so high ccr observed in mz might be due to environmental factors as well as shared genetic factors

Question 22

Explain what Tiernari’s study tells us about the role of genetics in schizophrenia.

Answer 22

Adopted children with biological mothers who have schizophrenia are more likely to develop the disorder than children whose biological mothers don’t have schizophrenia.

This suggests that genetics plays an important role in the development of schizophrenia.

Question 23

what were the control and experimental groups for Tienaris study

Answer 23

The experimental group was adopted children whose biological mothers had schizophrenia.

The control group was adopted children whose biological mothers did not have schizophrenia

Question 24

what study shows support for the genetic explanation using adoption studies

Answer 24

tienari

Question 25

findings of tienaris adoption study (3 things)

Answer 25

Children of biological mothers with schizophrenia were more likely to develop schizophrenia themselves. Similarities between the child and biological mother were due to genetics. Genetics had more influence on schizophrenia development than the environment

Question 26

What is one assumption made by adoption studies?

Answer 26

Biological parents of children adopted at birth can influence a child’s genes but not their environment.

Question 27

what does the neural correlates hypothesis state

Answer 27

The neural correlates hypothesis states that abnormal brain structure, such as enlarged ventricles , causes schizophrenia.

Question 28

what does dopamine do

Answer 28

Dopamine is involved in processing reward and in controlling attention.

Question 29

In the mesolimbic system, dopamine has an excitatory effect. This means that, if there are higher levels of dopamine...

Answer 29

neurons generate more electrical activity than normal causing overactivity in the mesolimbic system > +symptoms eg delusions

Question 30

What does the dopamine hypothesis suggest schizophrenia is caused by? (general)

Answer 30

abnormal brain function

Question 31

what did the revised dopamine H say about -symptoms

Answer 31

lower levels of dopamine in the frontal cortex than usual > underactivity causes -symptoms

Question 32

what does the revised dopamine hypothesis say we should seen in the brains of people with schizophrenia

Answer 32

hypodopaminergia in the cortex (abnormal dopamine systems) low levels of dopamine in cortex > negative symptoms

Question 33

support for DH: According to the dopamine a, if a person takes an amphetamine, which increases dopamine levels, what should occur?

Answer 33

increased activity in the mesolimbic pathway. healthy patients given amphetamines and get +symptoms

Question 34

what happened in nolls study

Answer 34

Noll reviewed previously conducted drug studies. In the studies, people with schizophrenia were given drugs that reduce dopamine levels. In the studies, the positive symptoms of people with schizophrenia were monitored.

Question 35

According to the dopamine hypothesis, what should we see in the brains of patients with schizophrenia? and link to an example

Answer 35

hyperdopaminergia in the subcortex (central regions of the brain) eg in brocas area, an increase in the dopamine receptors which could be responsible for auditory hallucinations and speech poverty

Question 36

Why did Montcrieff conclude that the evidence supporting the dopamine hypothesis is inconclusive?

Answer 36

Drugs that increase dopamine, like amphetamine, also increase the levels of other neurotransmitters, so we can’t be sure that it’s the increased dopamine that is causing these symptoms. Some post-mortem studies reported increased levels of dopamine in the mesolimbic pathway, but other studies reported no difference compared to the control brains.

Question 37

which neurotransmitters does amphetamines also increase as well as dopamine

Answer 37

serotonin and noradrenaline

Question 38

Name the researcher that criticised the dopamine hypothesis, by finding that amphetamine also increases noradrenaline and serotonin, alongside dopamine

Answer 38

montcrieff

Question 39

what is a strength of using antipsychotics as a treatment for sz - fully explained

Answer 39

comes from success of drug treatments. eg meta-analysis of 212 studies found that all the antipsychotics tested they were SIGNIFICANTLY more effective than a placebo in treating + and - symptoms done by reducing effects of dopamine also challenges classification of APs into typ/atyp as there wasnt much difference between the 2

Question 40

outline and evaluate genetics as a biological explanation for SZ (16) AO1- explained

Answer 40

one of bio exp is genetics. genetic exp see sz is heritable through transmission of dna. predicts higher risk of developing sz if a bio fam member has compared to not. and risk incr if genetic similarity is higher. eg 1st degree rel higher risk than 2nd and 3rd also identifying specific genes that predict development of sz using candidate genes (early studies - single gene but now polygenic ie multiple genes influence development also considers how gene mutation contributes ie genetics can still exp sz even in the absence of a family history of sz.

Question 41

outline and evaluate genetics as a biological explanation for SZ (16)