Biological explanations for schizo

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  • Created by: Gemma
  • Created on: 04-05-14 09:22
Which areas are studied?
Family studies (genetic factors), Twin studies (GF), Adoption studies (GF) and Dopamine hypothesis
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Family studies - main idea
Scizophrenia is a biological disease, in which can be transmitted via genetics- therefore those who have family members with schizo are more likely to be diagnosed
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Gottesman
Found that it was the closeness of the biological relatedness which related to the commonality of schizo appearing in an individual. 2 parents = 46%, 1 parent=13% , sibling = 9%
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Do other studies support the fact that schizo runs in families?
Yes
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AO2 of family studies/genetic factors?
Doesn't take into account psychological factors e.g. Expressed emotion whereby it is the negative emosh climate which leads to stress beyond individuals coping mechanism + so manifests itself as schizo
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What are MZ twins?
2 identical children who developed from the same zygote , which then split to give further embryos. They share 100% genetic info
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What are DZ twins?
2 non-identical children which developed from 2 separate zygotes. These children share 50% of genetic info
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Why is it so useful to study these twins?
Can give a real understanding of the contribution of biological factors in developing schizo. If purely biological then if 1 MZ twin has it , the other should; there should be a 100% concordance rate
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Joseph
Concordance rate of over 40% in MZ + just over 7% in DZ
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AO2 Joseph
Shows not purely biological + further studies into this area have found far lower rates. Joseph suggests it could be due to difference in environment, twins are expected to be treated the same, but aren't + therefore the rates could be showing this
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Why use adoption studies?
These studies are used to try and untangle genetics from environment; so if partlybiological, then could be predisposed genetically , but in fact if there is a certain environmental stimulus which triggers the schizophrenia to manifest itself
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Tienari et al
164 adoptees who had schizo mothers + 194 adoptees who didnt (control) - those with non-schizo mothers = 2% diagnosis and those with schizo = 6.7%
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AO2 Tienari et al
Not purely biological otherwise those with schizo mothers according to Joseph should have a 13% chance - suggests environment has a role to play
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What is the dopamine hypothesis?
Suggests unusual behavior + experiences of schio can be explained by changes in dopamine functions in the brain. Hypothesis suggests excess number of dopamine receptors (D2) @ post-synaptic membrane of neurone in schizo pps.
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What is the dopamine hypothesis? cont.
One suggestion is that the development of receptors in one area of the brain might lead to the inhibition of their development in another area, so explaining why there are diff numbers of dopamine receptors in diff parts of the brain.
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What is the dopamine hypothesis? cont.2
There is also a link between prefrontal cortex + schizo - this area doesn't finish developing until adolescence :( - can only observe this effect in adolescence. Much evidence comes from effect of drugs.
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What is the dopamine hypothesis? cont.3
Excessive activition of dopamine pathway is related to positive symptoms
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Problems with the dopamine hypothesis?
Only really can explain positive symptoms + so doesn't provide an explanation for the cognitive deficits that schizophrenics experience e.g. some social functions
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Corner
Dopamine neurons play a key role in guiding attention, so disturbances in this process may well lead to the problems relating to attention + thought found in people with schizo
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3 main drugs looked at ?
Amphetamines, antipsychotic drugs, Parkinsons disease - L-Dopa
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What are amphetamines?
Dopamine agonists, they stimulate nerve cells containing dopamine which causes synapses to be flooded with this - large doses = hallucinations
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What are antipsychotic drugs?
Block the activity of dopamine in brain, they eliviate hallucinates + delusions. Known as antagonists
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Parkinsons disease?
Low levels of dopamine activity found in those diagnosed with Parkinsons
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Grilly
Those with Parkinsons take L-dopa , which can bring about schizo symptoms
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Eval for drugs?
Many drugs used to treat schzio + reduce dopamine , actually end up producing more than the body needs + so the body tries to counteract the sudden imbalance
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Haracz
Post mortem of schizos - found those who had taken drugs to try + reduce dopamine levels = higher than those who didnt
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Implications?
If the basis of the disease can be understood , it can lead to better treatments being produced which will actually combat the symptoms of schizo
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Card 2

Front

Family studies - main idea

Back

Scizophrenia is a biological disease, in which can be transmitted via genetics- therefore those who have family members with schizo are more likely to be diagnosed

Card 3

Front

Gottesman

Back

Preview of the front of card 3

Card 4

Front

Do other studies support the fact that schizo runs in families?

Back

Preview of the front of card 4

Card 5

Front

AO2 of family studies/genetic factors?

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Preview of the front of card 5
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