neurotransmitter explanation for schizophrenia Flashcards
excess of dopamine in the brain - P1, A01
In the brain there is a neurotransmitter called dopamine.
It is thought that an excess of dopamine In the mesolimbic pathway can cause the positive symptoms of schizophrenia such as delusions and hallucinations.
There are suggestions as to why individuals experience an excess level of dopamine in there brain- low levels of beta hydroxylase may build up excess dopamine in synapses and proliferation of D2 dopamine receptors on postsynaptic cells may be responsible for hypodopaminergic activity.
strength of excess dopamine, study evidence - P1, A03
A strength of using dopamine as an explanation for schizophrenia is that there is study support from amphetamine-induced psychosis in rats.
Tenn et al in 2003 found that rats which were given nine amphetamine injections over three weeks showed various schizophrenic-like symptoms.
Dopamine antagonists (drugs which block D1 receptors) successfully reversed these effects.
Therefore, this study evidence suggests that increased dopamine levels may be a cause of schizophrenia in humans.
COUNTER ARGUMENT TO strength of excess dopamine, study evidence - P1, A03
However, Depatie and Lal in 2001 showed that apomorphine, a dopamine agonist which stimulates D2 receptors, doesn’t induce psychotic symptoms in non-psychotic clients and does not worsen symptoms in those already diagnosed.
Therefore, this challenges the suggestion that hyperdopaminergia is responsible for the positive symptoms of schizophrenia.
negative symptoms - P2, A01
A lack of dopamine in the mesocortical pathway is thought to cause the negative symptoms of schizophrenia such as lack of emotion and disorganised thought.
weakness of neurtransmitters as an explanation for schizophrenia - P2, A03
One weakness of using neurotransmitters as an explanation for schizophrenia is that there is evidence of schizophrenia in second-generation immigrants.
Neurochemical theories cannot explain why certain groups are more likely to be diagnosed with schizophrenia.
Veling et al in 2008 showed that Morrccan immigrants were more likely to be diagnosed than Turkish immigrants.
Therefore, this suggests that environmental factors may interact with internal neurochemistry making some people more prone to psychosis because of both factors.
counter argument to weakness of neurtransmitters as an explanation for schizophrenia - P2, A03
However, there is study evidence to show the role of D2 receptors as an explanation for schizophrenia.
Snyder in 1985 found that chlorpromazine is an antagonist at many dopamine receptors, D1 and D2, and has an antipsychotic effect.
He also found that the dopamine antagonist haloperidol is more effective even though it has a narrower range of biochemical effects.
This suggests that symptoms of schizophrenia can be caused by an excess of dopamine receptors in the brain.
Therefore this means that there is study evidence to show that a lack of dopamine receptors in the brain may cause symptoms of schizophrenia.
irregular seretonergic activity - P3, A01
It has been suggested that irregular serotonergic activity could be a cause of the negative symptoms of schizophrenia.
Clozapine binds to the serotonin receptors in the brain and has been found to reduce the positive and negative symptoms of schizophrenia which shows that too irregular serotonin activity may cause these symptoms.
weakness of neurotransmitters, reductionist - P3, A01
One weakness of using neurotransmitters as an explanation for schizophrenia can be considered reductionist.
A complex disorder which involves multiple symptoms is explain in terms of the action of one neurotransmitter, in this case serotonin.
But the experiences of one’s life who has schizophrenia is not represented at this biological level.
Therefore, using neurotransmitters as an explanation for schizophrenia is focusing solely on serotonin and is unlikely to represent the full nature of schizophrenia.
COUNTER ARGUMENT TO weakness of neurotransmitters, reductionist - P3, A01
However, using neurotransmitters as an explanation for schizophrenia has led to research which has discovered new treatments to help schizophrenic patients.
There has been research unveiled which shows that dopamine antagonists binding to D2 receptors can successfully reduce the positive symptoms of schizophrenia.
Also, atypical drugs such as clozapine which also blocks serotonin receptors have been successful in treating both positive and negative symptoms of schizophrenia.
This means that people can live with schizophrenia in the community without the need of residential care because their symptoms are able to be controlled.
dysregulation of dopamine - P4, A01
It has been thought that a dysregulation of dopamine within the brain can lead to schizophrenia. Researchers have suggested that when using neurotransmitters as an explanation for schizophrenia that attention should turn to the high levels of presynaptic dopamine instead f the irregularities of D2 receptors in the brain.
weakness of dysregulation of dopamine - P4, A03
One weakness of using neurotransmitters to explain schizophrenia is that it is a solely biological explanation.
Evidence for biological explanations is always in the form of a observed correlation and correlations do not show causation.
Therefore, this means that we cannot be sure whether unusual brain activity such as excess dopamine activity causes schizophrenia or whether schizophrenia causes unusual brain activity.
