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Discuss the genetic and biochemical explanations of schizophrenia

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Discuss the genetic and biochemical explanations of schizophrenia (25 marks) Biological explanations have been used in attempting to explain many mental disorders. However, such explanations have proved more successful in accounting for the development of schizophrenia than most other disorders. Two main branches of this type of explanation are genetic factors, which explain schizophrenia through inheritance of abnormal genes; and biochemical factors, which explain schizophrenia through the presence of abnormal neurochemicals. Nonetheless, there is contrasting evidence for both and it has been suggested that you can't completely separate these explanations from each other as schizophrenia is a complex and multi-cause disorder. In order to use twin studies to support genetic explanations of schizophrenia, when one twin is known to be schizophrenic, researchers are interested in the probability that the other twin may also be. This is known as concordance. Gottesman (1991) summarised 40 twin studies and found that the concordance rate was 48% when a monozygotic or identical twin had schizophrenia, but only 17% when a dizygotic twin or non-identical twin had schizophrenia. ...read more.


Despite large differences in concordance rates reported across twin studies and disagreements of their validity, two findings have been obtained repeatedly: identical and fraternal twins who have a co-twin with schizophrenia are much more likely than random members of the population to suffer from the disorder, and; among twins having a co-twin with schizophrenia, identical twins are at significantly greater risk than fraternal twins. This undoubtedly suggests that genetic factors play a significant part in the explanation of schizophrenia. Although, it may be better to consider environmental factors also. This can be seen in the study of adopted children. Tienari (1991) compared 155 adopted children who had a schizophrenic parent with 155 adopted children who did not have a schizophrenic parent. In all, 10.3% of those children with schizophrenic mothers developed the disorder, compared to only 1.1% of children without schizophrenic parent. Wahlberg et al. (1997) reported additional findings from this study, showing that environmental factors are also important. They found that children at genetic risk due to schizophrenic mothers had very good psychological health if raised by adopted families low in communication deviance (tendency to communicate in unclear and confusing ways). ...read more.


There is also more direct evidence based on post-mortem studies of schizophrenic patients. These showed that such patients had a greater density of dopamine receptors in certain parts of the brain than individuals not suffering from the disorder. There are, however, several problems relating to the dopamine hypothesis. Firstly, it is hard to assess brain levels of dopamine in patients with schizophrenia, this can only be done in a direct way by post-mortem assessment. It is also possible to assess dopamine in an indirect way. However this involves inserting a needle into the spine, which can be dangerous. The findings have generally been negative - patients with schizophrenia do not seem to produce more dopamine than other people. In conclusion, dopamine is probably of importance in understanding schizophrenia. However, it looks increasingly as if there are various complex differences in dopamine functioning between those with schizophrenia and healthy individuals. There is also the causality issue. If we find an association between having schizophrenia and having high levels of dopamine, the excessive dopamine levels might have played a part in causing the schizophrenia. However, it is also possible that elevated dopamine levels are in part a consequence of having schizophrenia. ...read more.

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