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Biological Explanations of Schizophrenia
The strength of biological explanations of schizophrenia can be seen in the support these have
received from research studies.
The involvement of genetic factors in schizophrenia can be seen in family studies such as that
carried out by Gottsman. These studies have established that the disorder is more common
among their biological relatives. For example, a concordance rate of 46% was found in children
who have both parents suffering from Schizophrenia. Compared to 13% where only one of their
parents was affected.
Opponents of genetic explanations suggest that the disorder may run in families because of
child rearing patterns, or other factors such as family conflict, as exemplified in Laing's study of
the girl who believed she was a tennis ball, which have nothing to do with heredity, raising issues
of nature versus nurture.
Further support for the argument of nature is found in twin studies. Joseph (2004) found that
pooled data for all studies of this type before 2001 show a concordance rate of 40.4% for
monozygotic twins and 7.4% for dizygotic twins. However, this researcher also points to the fact
that monozygotic twins are treated more similarly and they encounter similar situations in doing
more things together, the difference in the rates of schizophrenia can be explained more
convincingly as a result of environmental factors.
The difficulties of attempting to unravel the influence of nature and nurture for individuals
who share genes and socialisation are addressed by adoption studies. In a study with
acknowledged strength of reliability because of its sample size and control, Tiemanan et al used
164 adoptees whose biological mother had been diagnosed with schizophrenia. 11 of this sample
(6.7%) were also diagnosed with the disorder compared to just 4 (2%) of a control group born to
non-schizophrenic mothers allowing the researchers to conclude that the genetic liability to
schizophrenia had been "decisively confirmed." Despite the strength of its methodology adoption
studies would not have statistically significant findings, due to problems of sample size.
Several neurotransmitters have been implicated in schizophrenia but the most promising line of
research has focused on dopamine. The dopamine hypothesis states that messages from neurones
which transmit dopamine fire too easily or too often lead to the characteristics of schizophrenia.
Sufferers are believed to have an abnormally high D2 on receiving membranes resulting in more
dopamine binding and therefore more neurones firing. The neurones play a key role in guiding
attention, so disturbances in this process may lead to problems relating to attention, perception,
and thought found in schizophrenic sufferers.
Support for the dopamine hypothesis has been provided by post mortem examinations of people
with schizophrenia. These have discovered an increase in dopamine in parts of the brain. However,
in a review of such studies it was found that most of those with elevated levels had shortly before
death been prescribed anti-psychotic drugs which interfere with dopamine activity. This
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While advances in PET scanning has allowed researchers to investigate dopamine activity
more precisely, evidence for altered brain activity in schizophrenic sufferers has yet to be
Scanning has also allowed researchers to discover that many schizophrenia patients have
enlarged ventricles with Tory finding these to be about 15% larger than normal. Sufferers with
this characteristic also tend to display negative symptoms with greater cognitive disturbances
and poorer reaction to anti-psychotic drug.…read more