Schizophrenia-Biological explanations Flashcards
Strength, genetics, double whopper (impact sentence at the end), “Genetic Evidence”
There is strong evidence for genetic vulnerability as an explanation of schizophrenia from many sources.
Gottesman (1991) showed how genetic similarity and shared risk of schizophrenia are closely related.
If an identical twin has schizophrenia there is a 48% chance risk of the other twin developing schizophrenia. With non-identical twins it is 17%.
This suggests that genetic factors make some people more vulnerable to developing schizophrenia than others. Therefore, supporting the role of genetics as a biological explanation for schizophrenia
Strength, genetics, hamburger, “adoption evidence”
Further evidence for the role of genetics in the development of schizophrenia comes from Tienari et al. (2004).
They found that children of schizophrenia sufferers are still at heightened risk of schizophrenia if adopted into families with no history of schizophrenia.
This shows that nature has more of a role than nurture in the development of the disorder.
Limitation, genetics, double whopper, “Methodological problems”
There are methodological problems with the research used to support the genetic explanation.
Family, twin and adoption studies must be considered cautiously because they are retrospective, the impact of nature and nurture cannot be separated, and diagnosis may be biased by knowledge that other family members who may have been diagnosed.
This suggests that there may be problems when interpreting study findings. This reduces the validity of the results.
Limitation, genetics, double whopper, “Nature-Nurture problem”
It is very difficult to separate out the influence of nature vs nurture.
The fact that the concordance rates are not 100% for identical twins means that schizophrenia cannot wholly be explained by genes.
It could be the similarity of environments that causes schizophrenia, as there is an increased concordance rate for DZ twins compared to siblings.
This suggests that the genetic explanation cannot give a full explanation of the disorder.
Limitation, genetics, hamburger, “Biologically reductionist”
The genetic explanation of schizophrenia is biologically reductionist.
It focuses on the role of genes in the disorder and does not consider “larger” influences, for example the role of cognitions or the environment in the development of the illness.
It is likely that schizophrenia is caused by a combination of genetic and environmental factors and that focusing only on genes is over simplistic.
Strength, neural correlates (dopamine), double whopper, “Support for the dopamine hypothesis”
There is support for the involvement of abnormal dopamine functioning in schizophrenia.
Curran et al. (2004) found that dopamine agonists like amphetamines that increase the levels of dopamine make schizophrenia worse and can produce schizophrenia-like symptoms in non-sufferers.
Tauscher et al. (2014) found that antipsychotic drugs work by reducing dopamine activity. Both drugs studies suggest that there is an important role for dopamine in schizophrenia.
This increased the validity of the dopamine hypothesis as an explanation for the illness.
Strength, neural correlates (dopamine), hamburger, “More evidence for the dopamine hypothesis”
Further evidence for the involvement of dopamine in schizophrenia comes from Lindstroem et al (1999).
They completed a radioactive labelling study and found that the chemicals that are needed to produce dopamine are taken up faster in the brains of schizophrenia suffers than controls.
This suggests that schizophrenia sufferers are producing more dopamine.
Limitation, neural correlates (dopamine hypothesis), double whopper, “Other neurotransmitters involved”
There is evidence to suggest that dopamine does not provide a complete explanation for schizophrenia.
Some of the genes identified in by Ripke et al. (2014) code for the production of other neurotransmitters. It appears that although dopamine is likely to be one important factor in schizophrenia, so are other neurotransmitters.
This reduces the validity of the dopamine hypothesis as it does not consider the involvement of other neurotransmitters and their impact on the illness.
Limitation, neural correlates, double whopper, “The correlation-causation problem”
One criticism of the neural correlates explanations of schizophrenia is the correlation-causation problem.
It is not clear which comes first - are raised dopamine levels the cause of the schizophrenia, or is it the raised dopamine level the result of schizophrenia?
Furthermore, is it the lower activity levels in the ventral striatum that lead to the negative symptoms of schizophrenia, or is it the negative symptoms that mean less information passes through the ventral striatum resulting in the reduced activity?
The existence of neural correlates in schizophrenia explains very little about the disorder itself. This reduces the validity of the explanation.
Limitation, neural correlates, hamburger, “Biologically deterministic”
Neural correlate explanations of schizophrenia are biologically deterministic.
If an individual does have excessive amounts of dopamine, or lower activity levels in their ventral striatum, does it really mean that they will develop schizophrenia?
This explanation suggests that schizophrenia will be inevitable and we do not know that to be true.
