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Discuss one biological explanation for Schizophrenia [16 marks]
AO1
The dopamine hypothesis explains schizophrenia (at least partly) as a result of abnormal activity of the neurotransmitter dopamine.
The original version of the dopamine hypothesis suggested it was due to high levels of activity of dopamine in the subcortex (hyperdopaminergia).
For instance, an excess of dopamine receptors in Broca’s area (responsible for speech production) may be associated with poverty of speech and/or the experience of auditory hallucinations (negative symptoms)
However, the theory was updated because high levels of dopamine are not found in all schizophrenics. More recent versions have included hypodopaminergic, where low levels of dopamine in the prefrontal cortex are believed to be responsible for some of the negative symptoms of schizophrenia.
AO3
One piece of supporting research for the Dopamine hypothesis comes from Iversen 1979 who reported that during POST MORTEMS on people who had Schziphrenia that they found excess dopmaine in their limbic system. Therefore suggesting, that the neurotransmitter is involved in the disorder and supporting the dopamine hypotheisis. However, one limitation of post-mortem examination is the inability to establish causation which may reduce the validity of the dopamine hypothesis as an explanation for Schizophrenia.
One limitation of the dopamine hypothesis is that drugs that reduce dopamine levels do not always reduce the symptomps of Schizophrenia. This would suggest that there are different causes for different symptomps of Schizophrenia. This has been supported by Lieberman et al 2005 found that while drug medications effectively reduced positive symptoms, they had limited impact on negative symptomps (avolition and speech poverty) Therefore suggesting, that there must be other factors such as environmental factors (e.g. stress) which trigger the disorder.
One debate that could be applied to the Dopamine Hypothesis is the nature-nurture debate. The Dopamine hypothesis emphasises the nature side of the debate as it explains SZ as the result of abnormal activity of the neurotransmitter dopamine. However, this is a limitation as it ignores the role of nurture, environmental influences could also influence the development of the disorder. This has been supported by Tienari et al (2004) who supported the influence of family environment (nurture) on schizophrenia development among genetically vulnerable individuals. Therefore suggesting that the best approach to adopt here is an interactionist one, in particular the diathesis stress model. The diathesis-stress model suggests that schizophrenia results from a combination of genetic vulnerability (diathesis) and environmental triggers (stressors).
Evaluate the dopamine hypothesis [8 marks]
AO3
One piece of supporting research for the Dopamine hypothesis comes from Iversen 1979 who reported that during POST MORTEMS on people who had Schziphrenia that they found excess dopmaine in their limbic system. Therefore suggesting, that the neurotransmitter is involved in the disorder and supporting the dopamine hypotheisis. However, one limitation of post-mortem examination is the inability to establish causation which may reduce the validity of the dopamine hypothesis as an explanation for Schizophrenia.
One limitation of the dopamine hypothesis is that drugs that reduce dopamine levels do not always reduce the symptomps of Schizophrenia. This would suggest that there are different causes for different symptomps of Schizophrenia. This has been supported by Lieberman et al 2005 found that while drug medications effectively reduced positive symptoms, they had limited impact on negative symptomps (avolition and speech poverty) Therefore suggesting, that there must be other factors such as environmental factors (e.g. stress) which trigger the disorder.
One debate that could be applied to the Dopamine Hypothesis is the nature-nurture debate. The Dopamine hypothesis emphasises the nature side of the debate as it explains SZ as the result of abnormal activity of the neurotransmitter dopamine. However, this is a limitation as it ignores the role of nurture, environmental influences could also influence the development of the disorder. This has been supported by Tienari et al (2004) who supported the influence of family environment (nurture) on schizophrenia development among genetically vulnerable individuals. Therefore suggesting that the best approach to adopt here is an interactionist one, in particular the diathesis stress model. The diathesis-stress model suggests that schizophrenia results from a combination of genetic vulnerability (diathesis) and environmental triggers (stressors).
Outline the dopamine hypothesis [6 marks]
AO1
The dopamine hypothesis explains schizophrenia (at least partly) as a result of abnormal activity of the neurotransmitter dopamine.
The original version of the dopamine hypothesis suggested it was due to high levels of activity of dopamine in the subcortex (hyperdopaminergia).
For instance, an excess of dopamine receptors in Broca’s area (responsible for speech production) may be associated with poverty of speech and/or the experience of auditory hallucinations (negative symptoms)
However, the theory was updated because high levels of dopamine are not found in all schizophrenics. More recent versions have included hypodopaminergic, where low levels of dopamine in the prefrontal cortex are believed to be responsible for some of the negative symptoms of schizophrenia.
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