neurotransmitter explanation of SZ Flashcards
Increases in neurotransmitters in the brain, mainly dopamine, may cause schizophrenia. Research suggests that excess dopamine receptors at the synapse may be the cause.(AO1) Randrup and Munkvad ’66 injected rats with amphetamines to raise dopamine levels and found that their behaviour became aggressive and isolated which is consistent with psychotic behaviour.(AO3)
Excess dopamine in the mesolimbic pathway may cause positive symptoms.
Problems with dopamine functioning in the mesocortical pathway may cause negative symptoms. (AO1)Antipsychotic drugs to treat schizophrenia work by reducing levels of dopamine; this suggests high dopamine is linked to schizophrenia.(AO3) However, not all patients respond well to antipsychotics and Alpert and Friedhoff ’80 found that some schizophrenics show no improvement at all. This suggests there must be other factors causing schizophrenia.(AO3)
Newer research suggests hypersensitivity of certain dopamine receptors in the brain (D2 receptors); so sufferers may ‘overreact’ to dopamine.(AO1)There are other factors that might trigger the development of schizophrenia such as social, cognitive or environmental factors or other biological factors such as genes; therefore the explanation could be seen as reductionist by only focusing on neurotransmitters.(AO3)
Post-mortems on schizophrenics show that they have a higher density of dopamine receptors in certain parts of the brain compared to non-schizophrenics.(AO1)Evidence for this theory is only gathered after the onset of schizophrenia so we do not know if excess dopamine causes schizophrenia or if it is a result of having schizophrenia.(AO3)
Plus, early research, noted that patients who had abused large amounts of amphetamines (a dopamine agonist) showed positive symptoms of psychosis, such as hallucinations and delusions.(AO1) L-Dopa, a dopamine agonist, is often given to Parkinson’s sufferers and if the dosage is too high, (meaning dopamine levels are high) then it can cause schizophrenic type symptoms; supporting the idea that high dopamine is linked to schizophrenia.(AO3)
Newer research suggests that high serotonin and low glutamate may also play a role in the development of schizophrenia; and low glutamate may link to excess dopamine. (AO1)Some newer drugs work by blocking serotonin suggesting dopamine alone is not the cause and supporting the idea that various nts are linked to Sz.(AO3) Carlsson 2000, through a literature review, provides evidence that low glutamate is linked to Sz and that low glutamate can lead to high dopamine providing evidence of the role of different nts in Sz. (AO3)
