‘There is considerable evidence that schizophrenia is caused by biological factors. These can be genetic, neuroanatomical, biochemical, viral or a combination of such factors.’

Discuss biological explanations of schizophrenia. (9 marks +16 marks)

The biological explanation of schizophrenia looks at the role of genes, biochemistry, neuroanatomy and infection. This essay will focus on genetic and biochemical factors in the development of schizophrenia.

The genetic explanation of schizophrenia suggests that the disorder is inherited and therefore takes the nurture side of the nature nurture debate. There is much supporting evidence for this. For example Gottesman conducted a meta-analysis of 40 European studies that allowed him to calculate the concordance rate of relatives of a schizophrenia sufferer. The percentage risk of developing schizophrenia in the general population is 1% but Gottesman found this increased dramatically to 46% concordance for offspring of two schizophrenic parents and to 48% for monozygotic twins (MZ). Therefore the closer the degree of relatedness the higher the risk.His findings were challenged when another study found a concordance rate of 6% for dizygotic twins compared with Gottesmans 17% and a concordance rate of 28% concordance for MZ twins. This reduces the reliability of Gottesmans study but subsequent studies have produced similar statistics to Gottesman proving the original study to be robust.

It is difficult however to separate the genetic from the environmental factors with these studies. For example MZ twins share more similar environments than DZ twins as they are the same sex and therefore more likely to be treated more similarly. Another issues is that MZ twins share 100% of their genes so why are they not 100% concordant?

Adoption studies are used to help separate genetic from environmental factors. Heston assembled 47 adults who had been adopted at birth because their mothers were schizophrenic and a control group of 47 adults who were adopted but had normal mothers. They were all interviewed to establish whether they had developed the disorder. It was found that 5 of the 47 adoptees from schizophrenic mothers had been hospitalised with the disorder and none of the control group. Thus supporting the genetic link. The control group was essential for ruling out the possibility that stress and the ensuing environment of adoption was the cause of the developing schizophrenia.Although this study appears to conclusively show the link between genetics and schizophrenia there are methodological issues. For example the study was retrospective meaning that data may have been lost therefore the reliability of the study is challenged. Many of the adults were diagnosed at a time when classification of schizophrenia was highly unreliable also challenging the study’s reliability.The reanalysis of data from a number of adoption studies has shown there to be less support for genetic factors than the original researchers claimed.

Research by Crespi has identified 76 genes linked to schizophrenia. However 2/3 of schizophrenics do not have any relatives with the disorder. Biochemical explanations focus on the role of neurotransmitters in the brain. For example the dopamine hypothesis states that schizophrenia is caused an excess of the neurotransmitter dopamine at the synapses that use dopamine as their main transmitter. This has been tested through the use of drugs. For example Amphetamines administered to normal control patients in large doses can cause amphetamine psychosis the symptoms of which resemble schizophrenia and even small doses can increase the severity of symptoms in the sufferers. This is because the drug works by stimulating dopamine transmission in the brain.Phenothiazines are used to alleviate schizophrenia symptoms, the side effects of which resemble Parkinson’s disease. As Parkinson’s is associated with low levels of dopamine it suggests the drug works by reducing dopamine levels in the brain. However not all dopamine agonists such as amphetamines increase symptoms in schizophrenics and phenothiazine’s do not alleviate symptoms in all patients which is problematic for the dopamine theory

Biological explanations are reductionist in that they reduce a very complex disorder to something as simplistic as genetic inheritance. It is also determinist in that it does not take into account free will

Although biological explanations have much support and can provide reasons for the gender differences in onset (males develop schizophrenia earlier due to hormonal changes) environmental and genetic factors are still difficult to separate. Therefore a diathesis stress approach is appropriate because it states that any genetic predisposition to the disorder will need an environmental trigger. For example life events such as death in the family, as suggested by the psychodynamic approach could be seen as a chronic stressor that could trigger psychosis.

Examiner Comment The candidate shows generally accurate and reasonably detailed knowledge of two explanations and a range of relevant research evidence. Understanding of the explanations is reflected in the commentary as much as in the outline of the explanations. The commentary is well focused and shows coherent elaboration of most points. Confident use of appropriate terminology.There are a few places where the commentary could be improved by providing more sustained line of argument. There is no requirement to refer to issues and debates in unit 4 and the ref to reductionism and determinism in this script detract rather than add to the quality of the commentary.

AO1: 7 AO2/3: 14Total for this question: 21 marks = A*