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Biological explanations for
AQA A2 Psychology-
psychopathology (schizophrenia)…read more

Slide 2

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Genetic explanation
Suggests that one or more of our genes we inherit can put us
at risk of schizophrenia.
Gottesman (AO1)
· Investigated the concordance rates between a
schizophrenic individual and their family of having
· Found that monozygotic twins who have identical genes
only had a 48% concordance rate of developing
· Whilst this shows that schizophrenia can be genetic it also
shows that other factors affect it as we would expect the
concordance rates to be 100% is genes were the single
reason for developing schizophrenia…read more

Slide 3

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Genetic explanation
Gottesman (AO2)
· Unreliable as the study doesn't separate nature from
nurture- the chances of developing schizophrenia may
also be due to the way a person is brought up.
Therefore we can't be certain that all of the 48%
concordance rates are due to the MZ twins identical
genes.…read more

Slide 4

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Genetic explanation
Twin studies (AO1)
· Investigated the concordance rates for schizophrenia
between MZ and DZ twins. Found that MZ twins had
higher concordance rates than DZ twins. MZ twins had a
concordance rate of 39% whereas DZ twins had
concordance rates of only 5%.
· This shows that genes play a big role in explaining
schizophrenia as DZ twins have lower concordance rates
than MZ twins, because DZ twins only share 50% of their
genes unlike MZ twins who share 100%.
· This further suggests that MZ twins have a higher chance
of developing schizophrenia if their twin has
schizophrenia.…read more

Slide 5

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Genetic explanation
Twin studies (AO2)
· Conflicting evidence- genetic influence of MZ twins
varies between studies. Gottesman showed
concordance rates as 48% whereas this study showed
them as being only 39%. Therefore results are
unreliable due to the difference so we cannot be sure
that genes do affect the chances of developing
schizophrenia.…read more

Slide 6

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Genetic explanation
Kety et al (AO1)
· Studied siblings who were separated then adopted. Kety
found that the rate of chronic schizophrenia was 14% in
biological relatives which was higher than the rate of
chronic schizophrenia in the adopted family which was a
rate of 2.7%
· This shows that genes have a greater influence in
developing schizophrenia than the environment they were
brought up in.
· Also due to the fact that there was a rate of chronic
schizophrenia during adoption, even though it was a low
rate, this suggests that the stress caused by adoption
could also be a cause of schizophrenia if strong enough.…read more

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