biological (dopamine hypothesis) explanations

Question 1

the dopamine hypothesis

Answer 1

• dopamine is a neurotransmitter that causes neurons to fire, its responsible for transmitting signals between neurons in the brain
• the theory was updated by davis et al (1991) as high dopamine levels aren’t found in everyone with sz. they found the anti-sz drug clozapine (with little dopamine blocking activity) worked against sz

Question 2

the original dopamine hypothesis

Answer 2

hyperdopaminergia in the sub cortex
- focused on the possible role of high levels or activity of dopamine in the subcortex
- this excessive activity causes the neurons that respond to dopamine to fire too often and transmit too many messages
- this overload may produce many symptoms of sz

Question 3

the recent dopamine hypothesis

Answer 3

hypodopaminergia in the cortex
- focused on abnormal dopamine systems in the brains cortex which could explain negative symptoms
- abnormally low levels of dopamine activity

Question 4

give a strength of the dopamine hypothesis
1/2

Answer 4

it has real-world practical applications such as the development of effective treatments. due to research drugs like clozapine have been developed, which is more effective in treating sz behaviour than neuroleptics. therefore psychiatrists can understand the role of neurotransmitters when treating sz

Question 5

give a strength of the dopamine hypothesis
2/2

Answer 5

research suggests people with sz have more dopamine receptors, which may lead to more neural firing and so an over-production of messages. autopsies show a larger number of dopamine receptors, and an increased amount of dopamine in the left amygdala, caudate nucleus and putamen in those with sz. this suggests there is evidence of dopamine abnormalities in the brains of people with sz

Question 6

give a limitation of the dopamine hypothesis
1/3

Answer 6

newer drugs like clozapine are more effective than traditional ones. these affect other neurotransmitters like serotonin alongside dopamine, suggesting several neurotransmitters are involved in the development of sz. therefore this explanation may be too simplistic.

Question 7

give a limitation of the dopamine hypothesis
2/3

Answer 7

there is an issue with cause and effect: are the raised dopamine levels the cause or result of sz? lloyd et al state if dopamine is a causing factor, it is an indirect one mediated by environmental factors (e.g. abnormal family circumstances can cause high dopamine). therefore cause and effect cannot be established

Question 8

give a limitation of the dopamine hypothesis
3/3

Answer 8

dopamine abnormalities aren’t present in everyone with sz, especially those with neg symptoms. dopamine issues are associated more with pos symptoms so may only explain certain aspects of sz. davis et al (1991) suggests the variation of symptoms and types of sz implies several neurotransmitters are involved