Schizophrenia- Biological explanations

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Schizophrenia 2. Biological Explanations
Genetic Explanations
Family Studies.
Gottesman 1991 carried out meta analysis looking at the rates of Schizophrenia in
MZ (identical) and DZ ( twin. Found an MZ twin is more likely to get Schizophrenia if
the other twin is a sufferer. Mz has a high concordance rate (probability) than DZ.
The more genes we share with someone who is diagnosed with Schizophrenia the
greater chance we have of developing it. Children with two schizophrenic parents
have a concordance rate of 46%, children with one schizophrenic parent 13% and
siblings 9%.
Evaluation family studies:
Shared Environment ­ although not as high at MZ twins, DZ twins do show an
increased concordance rate of schizophrenia in comparison to the general public. This
means shared environment must play a part.
Multiple genes ­ Miyamoto et al argue that it is likely that many genes influence the
disorder as if has been impossible to identify 1.
Increased likelihood of having other disorders. Heston 1970 says if one twin is
schizophrenic there is a 90% chance the other twin will have some sort of mental
disorder. Suggests a predisposition for poor mental health and not necessarily for
schizophrenia alone.
Family studies: research has shown schizophrenia appears to run in families- supports
argument for a genetic basis for the disorder. Although now, researcher's say it may
be more to do with rearing patterns or other factors that have nothing to do with
heredity. Research on expressed emotional climate in some families lead to stress
beyond an individual's coping mechanisms.
Twin studies:
Offer unique opportunity for research into genetic and environment influences. MZ
twins share 100% genes are more similar in terms of a trait like schizophrenia than DZ
(fraternal) twins who only share 50%.
Joseph 2004- pooled data for all schizophrenic twin studies carries out prior to 201
shows a concordance rate for MC twins for 40.4% and for DZ twins 7.4%.
More recent methologically sound studies (researcher doesn't know whether thw
twin is MZ or DZ) have tended to report a lower concordance rate for MZ twins. Twin
research still argues that even these findings support genetic position, because they

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MC concordance rate that is many times higher than the DZ concordance
rate.
Evaluation: Twin studies
Enviroment for MZ and DZ twins are similar.
Shared Environment ­ although not as high at MZ twins, DZ twins do show an
increased concordance rate of schizophrenia in comparison to the general public. This
means shared environment must play a part.
Multiple genes ­ Miyamoto et al argue that it is likely that many genes influence the
disorder as if has been impossible to identify 1.…read more

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Joseph 2004 claims in countries like Denmark and Us, potential adoptive parents
would have been informed on genetic background of children prior to selection.
Kringlen 1987- as these adoptive parents know their background, it does wonder
who would adopt a child with a schizophrenic biological parent.
Neurochemical Explanations
Dopamine Hypothesis: Snyder 1976 argues that Schizophrenia is caused by the over
production of the neurotransmitter, Dopamine. Dopamine hypothesis states
messages from neurons that transmit dopamine too easily or too often, leading to
schizophrenic symptoms.…read more

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Because studies into dopamine activity in the brains of schizophrenics are carried out
after they have died its impossible to tell if increased dopamine causes Schizophrenia
or if Schizophrenia causing changes to the brain.
Brain scans ­ PET scans track the levels of dopamine in the brains of living patients.
The results show that although Dopamine is a key neurotransmitter however they
do not support the idea that over production of dopamine is the sole cause of
schizophrenia.
Drug Treatments ­ must consider individual differences.…read more

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MRI scans record radio waves from the brain, they are computerised to form a 3D
picture of the brains structure.
- They reveal definite structural abnormalities in the brains of schizophrenics.
- EVALUATION: Massive break through as it provides pictures of the living brain where
previous research had relied on post mortems and therefore couldn't be used to
help the patient when they are alive.
Pregnancy and Birth Factors
Overwhelmingly large no. Of schizophrenics are born in the winter and early spring.…read more

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