Biological Explanations of Schizophrenia- The Dopamine Hypothesis Flashcards
What does the dopamine hypothesis suggest?
- Schizophrenia is caused by elevated levels of dopamine at key synaptic sites within subcortical regions of the brain (e.g. the mesolimbic pathway and the limbic system)
- The excess of dopamine is argued to cause a ‘system overload’ where too many impulses are being transmitted, triggering positive symptoms of schizophrenia
- Dopamine neurons are instrumental in regulating attention, therefore if this process is disturbed it may lead to problems with attention, perception and though (which are all characteristics of schizophrenia)
What did Davis et al find?
- Pointed out that, in the prefrontal cortex, there are no D2 receptors and there appears to be a deficiency of dopamine in this region.
- He suggested that low levels of dopamine in this region (e.g. the mesocortical pathway) are more responsible for negative symptoms of schizophrenia, such as avolition.
What supports the dopamine hypothesis?
- Amphetamines as they are a dopamine agonist
- They stimulate the nerve cells which contain dopamine, causing the synapse to be ‘flooded’
- Large doses of the drug can cause hallucinations and delusions of a schizophrenic episode
If the point is:
A strength of the dopamine hypothesis as a biological explanation of schizophrenia is that there is prospective evidence to support the role of dopamine in schizophrenia.
What is the evidence and link?
Evidence- Randrup and Munkvad created schizophrenic like behaviour in a sample of rats by giving them dopamine agonists (amphetamines). They were given amphetamines to raise their dopamine levels 3 times a day for 6 days. The rats then showed long lasting abnormalities including being able to filter out irrelevant sounds. This was then reversed using anti psychotic medication.
Link- This suggests that the explanation can be seen as more reliable, due to the support that it has from research.
If the point is:
A weakness of the dopamine hypothesis as a biological explanation of schizophrenia is that, despite there being a clear relationship between high dopamine levels and schizophrenia, cause and effect cannot be inferred.
What is the explanation, evidence and link?
Evidence- We don’t know if high dopamine activity was there before the development of schizophrenia or if it increased because of developing schizophrenia.
Explanation- This is because the participant is rarely studied before they have a diagnosis, so we don’t know what their brain was like before.
Link- Hence, the dopamine hypothesis is merely correlational and as such of limited use.
If the point is:
A strength of the dopamine hypothesis as a biological explanation of schizophrenia is that it has made important practical applications to society.
What is the explanation, evidence and link?
Explanation- Understanding that schizophrenia is linked to elevated levels of dopamine in the mesolimbic pathway and limbic system has led clinicians to prescribe antipsychotics to patients.
Evidence- These work by blocking the activity of dopamine and are effective in up to 85% of patients with schizophrenia.
Link- This implies that the dopamine hypothesis for understanding the cause of schizophrenia has tangible effects in society by helping patients reduce their symptoms.
If the point is:
A strength of the dopamine hypothesis as a biological explanation of schizophrenia is that it is scientific.
What is the explanation, evidence and link?
Explanation- This is because brain chemistry can be studied in a controlled, objective and falsifiable manner.
Evidence- For example, neurotransmitter levels, such as dopamine levels within schizophrenic patients, by analysing blood samples, cerebro spinal fluid and PET scans.
Link- This implies that the dopamine hypothesis account of schizophrenia promotes psychology as a rigorous scientific subject which is worth more government funding.
What are the evaluation points for the dopamine hypothesis as a biological explanation of schizophrenia?
+ Prospective evidence to support the role of dopamine in schizophrenia
— Despite their being a clear relationship between high dopamine levels and schizophrenia, we cannot infer cause and effect
+ Made important practical applications to society
+ Scientific explanation
