Biological explanation

Question 1

What is the genetic explanation of SZ?

Answer 1

• Candidate genes are individual genes associated with the risk of inheriting schizophrenia
• Most likely genes would be those coding for neurotransmitters including dopamine
• It is polygenic, a number of genes give an increased risk (108 separate genetic variations)
• It is aetiologically heterogenous, different combinations of genes are linked to it

Question 2

What is the dopamine hypothesis (hyperdominergia)

Answer 2

• Hyperdopaminergia in the sub-cortex, means too much areas of the brain. (EG: Broca’s area is responsible for speech production. Leads to poverty of speech and or auditory hallucinations)
• High levels of dopamine activity results in positive symptoms of schizophrenia
• High levels of dopamine receptors in Broca’s area and auditory cortex

Question 3

What is the dopamine hypothesis (hypodominergia)

Answer 3

• Hypodopaminergia in the cortex, too little in the cortex of the brain. (EG: prefrontal cortex is responsible for thinking and decision making. Leads to negative symptoms)
• A deficit in dopamine activity which leads to negative symptoms of schizophrenia

Question 4

What are the neural correlates?

Answer 4

• Hypodominergia/ dopamine abnormally low in the prefrontal cortex. It is responsible for thinking, hence why it can explain cognitive problems such as negative symptoms.
• Hyperdopaminergia/ excess dopamine activity high in the mesolimbic pathway associated with positive symptoms.

Question 5

Strength of genetic: family studies

Answer 5

• Gottesman > found identical twins had a 48% risk of developing SZ and fraternal twins had a 17% risk.
• Tienari > adoption study of Finnish children with SZ mother compared to matched control group, found biological children with SZ are at a heightened risk even if they grow up in an adoptive family.

Question 6

Weakness of genetic: environmental factors

Answer 6

• Does not consider environmental factors
• Evidence that cannabis can increase the development of SZ up to 7x
• Other psychological risk such as childhood trauma leaves people more vulnerable
• Genetic factors alone cannot provide a complete explanation for SZ

Question 7

Strength of neural: evidence for dopamine

Answer 7

• Evidence of amphetamines increase dopamine and worsen symptoms in people with SZ and induce symptoms in people without
• Antipsychotic drugs reduce dopamine activity and also reduce intensity of symptoms
• Strongly suggests dopamine is involved in the symptoms of SZ

Question 8

Weakness of neural: central role of glutamate

Answer 8

• Post-mortem and live scanning studies consistently found raised levels of glutamate in several brain regions of people with SZ
• Several candidate genes for SZ are believe to be involved in glutamate production or processing
• Limits dopamine hypothesis, an equally strong case can be made for other neurotransmitters