SZ 03 Neural correlates / dopamine hypothesis

How does the dopamine hypothesis explain positive symptoms of schizophrenia? (3)

Positive symptoms caused by...

* High levels of dopamine (hyperdopaminergia) ...

* ...at D2 receptors ...

* ...in subcortex

How does the dopamine hypothesis explain negative symptoms of schizophrenia? (3)

Negative symptoms caused by...

* Low levels of dopamine (hypodopaminergia) ...

* ...at D1 receptors ...

* ...in prefrontal cortex

Explain why the findings of Howes' scanning study support the dopamine hypothesis of schizophrenia (3)

* Review of PET scans

* Moderate- high difference in levels of dopamine at D2 receptors between patients and controls

* Suggests that high dopamine causes positive symptoms

Explain why drug trials of antipsychotics (APs) support the dopamine hypothesis of schizophrenia (4)

(Bonus: why are trials especially strong evidence?)

* APs block dopamine (DA) receptors

* Reduce DA at D2 receptors

* APs are effective

* Suggests high DA was the problem / cause in the first place.

(Bonus: clinical trial = experiment => evidence of causal relationship, so strong evidence for role of DA)

Explain how schizophrenia could be due to glutamate instead of dopamine (3)

•High glutamate may be the ultimate / primary cause of DA dysfunction...

* ... and all symptoms of SZ

* So DA is a proximate / secondary cause