Outline and evaluate biological explanations of schizophrenia (essay)

24 mark essay: Outline and evaluate biological explanations of schizophrenia
word of advice (from experience)= don't be lazy and refer to schiz/schizo's throughout you'll lose marks!  
Hope it's useful(:  

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`Outline and evaluate biological explanations of schizophrenia' (24 marks)
The biochemical explanation offers one explanation for the cause of schizophrenia in
terms of neurotransmitter release. It suggests that schizophrenia could be caused by
an excess of dopamine and a message overload in the brain. This is due to receptor
cells requiring dopamine to fire so with a large amount of dopamine present it is
activated too much and too many messages are sent. This is what could account for
the confused and erratic behaviour seen in schizophrenic patients.
Support for this theory is the effect of amphetamines: type of drug commonly known
as `speed'. These drugs work by significantly increasing dopamine levels. When given
to a non- schizophrenic the individual has been found to develop schizophrenic-like
symptoms, this therefore suggests that the increased dopamine levels is likely to be
linked to the disorder. In addition patients with schizophrenia have been found to have
symptoms worsen when they've taken amphetamines.
Further support is the use of antipsychotics, drugs that work by blocking dopamine
receptor cells and thus inhibiting firing and message overload. These drugs are used to
treat schizophrenics and so have been proven effective in reducing symptoms. This
supports the explanation as the drug is clearly effective and so reinforcing the fact
there may well be a causal relationship between dopamine message overload and
Antipsychotic support can be criticised since once individuals begin taking the drug the
blocking occurs relatively quickly so symptoms should improve straight away. This
however is not the case, it take a while for schizophrenic patients to have improved
symptoms so the disorder can't be purely dopamine and other factors must be
involved having an effect.
It can also be criticised due to the treatment aetiology fallacy (TAF) whereby you
cannot necessarily assume excess dopamine is the direct cause. TAF essentially works
backwards in the sense that from an effective treatment, a cause can be established.
For example a drug that prevents dopamine message overload helps relieve
schizophrenic symptoms so it is therefore assumed schizophrenia is caused by
message overload of excess dopamine. It is much better to firstly find the cause of
the disorder and then develop treatments after. In response to this criticism a
second dopamine hypothesis was introduced which suggests rather than excess
dopamine causing the message overload, it may in fact be that schizophrenics have
too many receptor cells and thus more cells than normal fire, causing the message
overload. Owen's research supports this theory, since in autopsy's taken on
schizophrenic and non- schizophrenic individuals have shown more dopamine
receptor cells to be present in schizophrenics.
Another explanation is neuroanatomy, where schizophrenia has been suggested to
be caused by structural and functional difference in the individual's brain. PET scans
have shown that type 1 schizophrenics have reduced functioning in their temporal

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PET scans
reveal low activity in the frontal lobe. These differences between schizophrenics
and non- schizophrenics brains suggest that it is a brain abnormality that may be the
cause of the disorder. However the differences between the two types of
schizophrenia also suggest that it may be two different disorders, with two different
MRI scans also show differences whereby schizophrenics' brains show larger
ventricles.…read more



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