dopamine hypothesis

Question 1

what does the dopamine hypothesis state

Answer 1

• schizophrenics have high levels of dopamine in their brain
• s1 is caused by excess dopamine activity
• states that the brain of s1 produce more dopamine than normal brains
• lowering DA can help remove the symptoms of s1

Question 2

what is parkinson’s disease

Answer 2

neurological condition and not curable
low levels of dopamine
L-dopa raises DA activity
people with parkinsons disease develops s1 symptoms if they take too much L-dopa

Question 3

role of drugs

Answer 3

amphetamines lead to increase in DA levels
large quantities lead to delusions and hallucinations
if drugs are given to s1 patients their symptoms get worse

Question 4

post mortem

Answer 4

FALKAI ET AL
autopsies have found that people with s1 have a larger than usual number of dopamine receptors
increase in DA in brain structures and receptor density (Left amygdala and caudate nucleus putamen)

Question 5

schizophrenia or fault chemicals???

Answer 5

fault chemicals cause s1 but s1 may cause faulty chemicals

drugs may influence other systems that impact on schizophrenia so cant be 100% sure about their effects

Question 6

evaluation

strengths

Answer 6

• drugs given to s1 patients often work by blocking dopamine receptors. if the receptors are blocked then less dopamine can be taken up
• scanning techniques have shown that s1 are more sensitive to dopamine uptake. when given amphetamines those with s1 release a greater amount of dopamine than non- s1 , suggesting that those with s1 are more sensitive to excess dopamine
• sufferers from parkinson’s disease who are given l-dopa can experience symptoms similar to s1
• genes that are likely to increase sensitivity to dopamine are found in those who develop s1 symptoms
• those with s1 appear to have differences in their brain which can be linked to sensitivity to dopamine
• FIGEE ET AL looked at 13 studies using MRI scans to see the effect of antipsychotic drugs on the brain

Question 7

weaknesses

Answer 7

• drugs that block dopamine receptors take immediate effect but a reduction in symptoms is not noticed until a few days afterwards. suggests something else may be contributing
• amphetamines only produce + symptoms suggesting that the dopamine explanation is insufficient
• excess dopamine receptors in everyones brain - the same amounts were found in non s1. s1 have lower levels of dopamine in prefrontal lobes so not always a case of excess dopamine
• pet scans show that blocking dopamine receptors doesnt always stop symptoms

Question 8

both evaluation

Answer 8

• effect of amphetamines - these drugs can cause excess dopamine causing symptoms of s1. however excess dopamine can also have a stimulant effect producing symptoms such as overconfidence and high alertness which are not present in cases of s1
• PET scans show that dopamine blocking drugs were not effective in patients who have had s1 for 10 years or more. if administered early, more than 90% patients respond