schizophrenia - 1.2

Question 1

genes

Answer 1

sections on DNA that control production of a particular protein

Question 2

alleles

Answer 2

different versions of a gene

they lead to different biological outcomes

Question 3

genetic risk alleles

Answer 3

more genetic risk alleles a person carries, more likely they are to develop schizophrenia

Question 4

concordance rate

Answer 4

% of twins that both same the share trait, given that at least one twin has the trait

Question 5

what does a high concordance rate mean?

Answer 5

genetics has a big influence on the trait compared to other factors

Question 6

Gottesman and Shields twin study findings and conclusion

Answer 6

found that there was a 74% concordance rate in MZ twins and a 24% rate in DZ twins

SZ is particularly influenced by genetics, however CR wasn’t 100% so development of SZ is also through environment

Question 7

twin studies limitations

Answer 7

assumes MZ and DZ twins have similar amount of shared environment

MZ twins are more likely to be treated the same (dressed the same) than DZ twins so high CR could be due to shared environment as well as genetics

could overexaggerate importance of genetics

Question 8

adoption studies

Answer 8

supports genetic explanation

researchers investigate children not brought up by bio parents

if adopted at birth, bio parents could have genetic influence but not environmental one

Question 9

what type of study was Tienari et al?

Answer 9

adoption study

Question 10

what type of study was Gottesman and Shields?

Answer 10

twin study

Question 11

Tienari et al procedure

Answer 11

adoption study

compared 2 groups of adopted children

experimental group - mothers had SZ
control group - mothers didn’t have SZ

examined number of children with SZ

% of children with SZ significantly larger in experimental group

Question 12

Tienari et al findings

Answer 12

% of children with SZ significantly larger in experimental group

Question 13

Tienari et al conclusion

Answer 13

genetics play an important role in development of schizophrenia

genetics had more influence than the environment

Question 14

adoption studies limitations

Answer 14

assume that similarity between bio parent and adopted child is solely due to genetics

ignore similarities in environments shared between adopted children and bio parents

adopted children are often matched with parents similar to bio parents

therefore SZ may be caused by environmental factors as well as genetics

Question 15

how do genes influence our behaviour?

Answer 15

by controlling processes in our brain

may cause abnormalities in the brain which can cause SZ

Question 16

2 main hypotheses for which brain abnormalities cause SZ

Answer 16

neural correlates hypothesis

dopamine hypothesis

Question 17

neural correlates hypothesis

Answer 17

SZ is caused by abnormal brain structure

those with SZ have larger ventricles and a smaller frontal cortex

Question 18

neural correlates hypothesis study support

Answer 18

comes from MRI scans - provide image of structure of brain

Torrey (2002) conducted MRI scans

control group - brains of people without SZ
experimental group - had SZ

participants with SZ had on average 15% larger ventricles

Question 19

neural correlates hypothesis limitation (effects of medication on brain structure)

Answer 19

evidence obtained from MRIs is correlational

drug medication could act as confounding variable in studies of neural correlates

enlarged ventricles could be due to taking drugs

no cause and effect

MRIs look at brains after SZ development, hard to tell if ventricles were enlarged beforehand

Question 20

neural correlates hypothesis limitation (individual differences)

Answer 20

neural correlates hypothesis - SZ is caused by abnormal brain structure

some studies have found no significant difference in ventricle sizes

results haven’t always replicated

some studies have reported different abnormalities e.g. different brain shape or reduction in number of neurons

therefore, abnormal brain structure can’t be cause of SZ in all patients otherwise they would have same abnormalities

Question 21

dopamine hypothesis

Answer 21

states SZ caused by higher dopamine levels than normal and overactivity of neurons in mesolimbic system

explains positive symptoms

Question 22

dopamine

Answer 22

involved with processing reward and controlling attention

Question 23

what are levels of dopamine like in people with SZ?

Answer 23

higher than normal

Question 24

where does neuron overactivity occur in patients with SZ?

Answer 24

mesolimbic system

Question 25

why does neuron overactivity occur in patients with SZ?

Answer 25

there is too much dopamine

more electrical overactivity is generated than those of healthy people

Question 26

effects of high levels of dopamine

Answer 26

delusions and hallucinations

positive symptoms

neural overactivity

Question 27

revised dopamine hypothesis

Answer 27

explains negative symptoms

suggests in other parts of the brain, levels of dopamine are too low

frontal cortex in particular

low levels of dopamine cause underactivity of neurons in frontal cortex

Question 28

effects of low levels of dopamine

Answer 28

neural underactivity in frontal cortex

negative symptoms

Question 29

dopamine hypothesis (study support)

Answer 29

drug studies

when normal people take amphetamines (drugs which speed up messages between brain and body and increase dopamine) they experience hallucinations and delusions

drugs that reduce dopamine decrease chance of SZ patients having hallucinations and delusions

Question 30

limitation of dopamine hypothesis (drugs don’t always work)

Answer 30

we expect drugs to reduce dopamine levels to reduce positive symptoms according to hypothesis

a researcher reviewed all of the drug studies where doctors gave drugs to SZ patients to reduce dopamine levels

for 1/3 patients drugs didn’t work

therefore high levels of dopamine aren’t only cause of positive symptoms

Question 31

limitation of dopamine hypothesis (might be other neurotransmitters)

Answer 31

drugs that cause hallucinations and delusions (amphetamines) don’t just increase dopamine activity, they also increase activity of serotonin and noradrenaline

therefore could be other neurotransmitters

Question 32

limitation of dopamine hypothesis (post mortems)

Answer 32

a researcher reviewed studies that used post mortem exams to look at changes in dopamine levels of SZ patients

we should see increased levels of dopamine in mesolimbic system

researcher found lots of studies reported no difference in levels of dopamine compared to control brains (no SZ)

therefore there is little evidence to support