Biological explanations for schizophrenia

A01 and A02 , essay plan for 24/24 marks 

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  • Created on: 22-12-13 20:41
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A01- The Genetic explanation of Schizophrenia proposes that the
disorder is hereditary ­ it runs in families.
A01- family studies show that the risk of developing schizophrenia is
greater for those more closely related to the schizophrenic.
A01-Kendler et al (1985) found that 1st degree relatives of those
with schizophrenia are 18 times more at risk than the general
A01- Gottesman (1991) did a meta-analysis on 40 twin studies and
found that with MZ(identical) twins there was a 48% concordance
rate but in DZ(non identical) twins there was a 17% concordance
rate. A02- This shows a genetic link for Schizophrenia, if there was
no genetic factor then there should be no difference between MZ
and DZ twins. The fact that there's a difference suggests a genetic
A01- concordance rates are the chance that someone will develop a
disorder if their related to someone who has it.
A01- Sheilds (1962) found that MZ twins raised in different families
still showed around 50% concordance reinforces that genetics is
more significant than environment.
A01- Torrey (1994) reviewed evidence from twin studies, finding
that if one MZ twins develops the condition there is a 28% chance
the other twin will suggesting genetics play a role in the
development of schizophrenia.
A01- Malaspina found that patients who have schizophrenia in their
family histories are more likely to develop negative symptoms than
those families who are schizophrenia free.

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A01- Joseph who looked at nine of the most recent studies
conducted and found the concordance rate for MZ twins to be
22.4% and for DZ 4.…read more

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A01- Post mortems and PET scans show that schizophrenics have
abnormally high levels of dopamine this supports the dopamine
A01- Seeman (1987) found increases in dopamine receptor density
of between 60 ­ 110 % compared to controls.
A01- PET scans ( live investigation of the brain) Wong et al ( 1986)
found a 2-fold increase in density of dopamine receptor sites in
schizophrenic patients who hadn't been treated with
anti-psychotics.…read more

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A01- Young et al (1990) found a number o structural differences in
MRI scans when comparing the brains of schizophrenic and
non-schizophrenic individuals this suggests that brain differences
are strongly linked with the development of schizophrenia.
A01- Psychologists have reported that some schizophrenics have
difficult births which could have starved their brains of oxygen.
A01- Chua & Mckenna (1995) found Enlarged ventricles, Smaller
corpus collosum in schizophrenics suggesting brain abnormalities
are linked with schizophrenia.…read more

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A02- If there was no genetic link then there should be no difference
in the level of risk between first degree relatives and the public.
A02- the fact that concordance rates increased with genetic
relatedness may be explained by the fact that families are likely to
spend more time together which means environmental factors may
be influenced .…read more

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A02- Consistent evidence which makes it very reliable
A02- Theory is based on nature alone so it is reductionist and highly
A02- Family, twin and adoption studies must be considered
cautiously because they are retrospective and may be biased by
knowledge that another family member has been diagnosed.
A02- The sample size of twin, family and adoption studies tends to
be small so population validity may be low.
A02- Even MZ twins reared apart share a womb so environmental
factors cannot be discounted.…read more

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A02- One of the most commonly used theories because it can be
proved empirically so it's more convincing.
A02- Healy (2000) believes pharmaceutical companies were keen to
see the dopamine theory promoted because they would make huge
profits from manufacturing anti-schizophrenic drugs that inhibited
dopamine production.
A02- Brain abnormalities are not consistent amongst schizophrenics
so the Neuroanatomical approach is not reliable.…read more


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