Dopamine Explanation of Schizophrenia

Question 1

What is the overview of the hypothesis?

Answer 1

Sz is caused by chemical imbalances in the brain, specifically, the overproduction of dopamine.

• high levels of DA = development of symptoms and illness
• high levels cause the neurons that use DA to fire excessively and transmit too many messages. This message ‘overload’ may produce many of the symptoms. Associated with paranoia.

Question 2

What are the three ways that dopamine can influence Sz?

Answer 2

• high levels
• too many dopamine receptors
• sensitivity to dopamine (possibly genetically inherited)

Question 3

Which symptoms is dopamine specifically linked to?

Answer 3

Over-activity of dopamine controlled synapses = hallucinations and paranoia.

Question 4

How does the dopamine explanation link with brain areas?

Answer 4

• high DA in mesolimbic system = positive symptoms

- high DA in meso-cortical system = negative symptoms

Question 5

Supporting evidence?

Answer 5

+ Carlsson (1999/2000): found that high levels of DA is linked to development of psychosis/Sz through brain structure scan studies e.g. Abi-dargham et al. (1998) and Breier et al. (1997).
+ Seeman (2013): found that Sz’s have a higher amount of D2 receptors.
+ Randrup and Munkvad (1966): injected rats with amphetamines to raise DA levels and they began showing psychotic-type behaviours e.g. aggression, isolation, which are linked to Sz.

Question 6

Conflicting evidence?

Answer 6

• Carlsson (1999/2000): also found that there are other neurotransmitters which play a role e.g. glutamate.
• Kwon et al. (1999): found that there was a 25% reduction of grey matter in the frontal and temporal lobes of Sz’s = may be caused by other brain differences.

Question 7

Other theories?

Answer 7

• genetics: inherited through genes, particularly the C4-A gene which intensifies synaptic pruning, putting them at greater risk of developing Sz.

Question 8

Usefulness?

Answer 8

+ useful for drug treatments e.g. drugs which reduce dopamine levels

• but drugs don’t work instantly
• cause and effect - does Sz = high DA or other way or 3rd variable
• doesn’t account for social factors e.g. environmental breeder

Question 9

Testability?

Answer 9

+ objectively measured = neurotransmitters in the brain = scientific