Biological explanation for schizophrenia

Question 1

What are the 3 aspects of the biological explanation for schizophrenia?

Answer 1

Genetic basis
Dopamine hypothesis
Neural correlates

Question 2

Name 4 studies that support a genetic basis for schizophrenia.

Answer 2

Gottesman - twin studies and family studies
Ripke - molecular study
Tienari - adoption studies

Question 3

What did Gottesman find in his twin studies?

Answer 3

Concordance rate for schizophrenia:

• MZ = 48%
• DZ = 17%

Question 4

How many twins did Gottesman study?

Answer 4

40

Question 5

What did Tienari find in his adoption studies?

Answer 5

Studied 155 adopted children who’s biological mothers had schizophrenia.
Concordance rate of 10% compared to 1% in adopted children without schizophrenic parents.

Question 6

What did Gottesman find in his family study?

Answer 6

If both your parents suffer from schizophrenia, then you have a 46% chance of developing it yourself.

Question 7

Schizophrenia is polygenic. What does this mean?

Answer 7

It is determined by more than one gene.

Question 8

Why is schizophrenia aetiologically heterogenous?

Answer 8

Because studies have identified different candidate genes.

Question 9

What did Ripke find out in his study of genetic vulnerability?

Answer 9

• Carried out a study combining all previous data from genome-wide studies of schizophrenia.
• The genetic make up of 37,000 schizophrenics was compared to that of 113,000 controls.
• 108 separate genetic variations were associated with increased risk of schizophrenia.

Question 10

What is dopamine?

Answer 10

A neurotransmitter that generally has an excitatory effect and is associated with the sensation of pleasure.

Question 11

What levels is hyperdopaminergia associated with?

Answer 11

High levels of dopamine in the sub cortex.

Question 12

Give an example of hyperdopaminergia’s role in schizophrenia.

Answer 12

An excess of dopamine receptors in Broca’s area may be associated with speech poverty/the experience of auditory hallucinations.

Question 13

What levels is hypodopaminergia associated with?

Answer 13

Low/abnormal levels of dopamine in the cortex.

Question 14

Give an example of hypodopaminergia’s role in schizophrenia.

Answer 14

Goldmann-Rakic identified a role for low levels of dopamine in the prefrontal cortex (responsible for thinking and decision making) in the negative symptoms of schizophrenia.

Question 15

What are neural correlates?

Answer 15

Measurements of the function of the brain that correlate with an experience.

Question 16

Give an example of a negative symptom that provides evidence for neural correlates as an explanation.

Answer 16

• Avolition involves the loss of motivation.
• Motivation involves the anticipation of a reward, and the ventral striatum is believed to be involved in this anticipation.

Question 17

Who conducted a study into the ventral striatum’s role in schizophrenia?

Answer 17

Juckel

Question 18

What did Juckel find?

Answer 18

Measured activity levels in the ventral striatum in schizophrenia and found lower levels of activity than those observed in controls.

Question 19

Who conducted a study into neural correlates effect on positive symptoms in the development of schizophrenia?

Answer 19

Allen et al.

Question 20

What was Allen’s study?

Answer 20

• Scanned the brains of patients experiencing auditory hallucinations and compared them to a control group whilst they identified pre-recorded speech as theirs or others.
• Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus were found in the hallucination group.

Question 21

State a positive of the biological explanation for schizophrenia.

Answer 21

Multiple sources of evidence for genetic susceptibility:

• Gottesman x2
• Ripke
• Tienari

Question 22

State 3 negatives of the biological explanation for schizophrenia.

Answer 22

Mixed evidence for the dopamine hypothesis:
- L-Dopa
- Antipsychotic drugs
- Ripke: other neurotransmitters
The correlation-causation problem.
Environmental influence is unclear.