Biological Explanations

Question 1

Gottesman (1991):

Answer 1

• identical twins have a 48% shared risk of schizophrenia
• parents have a 6% shared risk
• fraternal twins have 17% shared risk
• grandchildren have a 5% shared risk

Question 2

Polygenic

Answer 2

Requires a number of factors to work in combination for the development.

Question 3

Ripke et al. (2014):

Answer 3

Combined all previous data from genome-wide studies:

• genetic make-up of 37,000 patients compared for 113,000 controls
• 108 separate genetic variations associated
• genes associated with risk included those coding for the functioning of a number of neurotransmitters including dopamine.

Question 4

Aetiologically heterogenous

Answer 4

Different combinations of factors can lead to condition.

Question 5

Tienari et al. (2004):

Answer 5

Children of schizophrenia sufferers are still at a heightened risk even if adopted.

Question 6

The dopamine hypothesis

Answer 6

Dopamine is widely to believed to work differently in patients.
- important in the functioning of several brain systems that may be implicated in symptoms of schizophrenia.

Question 7

Hyperdopaminergia

Answer 7

High or excess levels of dopamine activity in the subcortex.

Question 8

Hypodopaminergia

Answer 8

Low levels of dopamine activity in the pre-frontal cortex.

Question 9

Goldman-Rakic et al. (2004):

Answer 9

Identified the role of hypodopaminergia in the prefrontal cortex within negative symptoms of schizophrenia.

Question 10

Curren et al. (2004):

Answer 10

Dopamine antagonists (e.g. Amphetamines) that increase levels of dopamine make schizophrenia worse in patients and produce schizophrenia-like symptoms in non suffers.

Question 11

Lindstroem et al. (1999):

Answer 11

Found the chemicals needed to produce dopamine are taken up faster in schizophrenia sufferers - suggests they produce more dopamine.

Question 12

Juckel et al. (2006):

Answer 12

Activity levels are lower in the ventral striatum in schizophrenia patients.
Overall negative correlation between activity levels and severity of negative symptoms.
Neural correlate of negative symptoms.

Question 13

Allen et al. (2007):

Answer 13

Scanned the brains of patients experiencing auditory hallucinations.

• Lower activation levels in the superior temporal gyrus and anterior cingulate gyrus found in the hallucination group.
• Neural correlate of auditory hallucinations

Question 14

Davis et al. (1991):

Answer 14

High levels of dopamine not found in all sufferers.

• Clozapine has very little dopamine blocking activity but works effectively against schizophrenia
• High levels of dopamine in the a mesolimbic dopamine system associated with positive symptoms
• High levels in the mesocortical dopamine system association with negative symptoms

Question 15

Iversen (1979):

Answer 15

Post-mortems on patients who’d had schizophrenia found excess dopamine in the limbic system

Question 16

A03 points for biological explanations:

Answer 16

• focuses entirely on nature and ignores nurture and the environment
• Tienari et al. - still heightened risk if adopted
• Curren et al. - amphetamines produce schizophrenia-like symptoms
• Lindstroem et al. - chemicals taken up faster in sufferers
• lack of cause and effect - correlation may be due to other issues
• validity - can still occur with no family history
• concordance rates not 100% between MZ twins - must be other factors
• over simplistic and thus reductionist - other neurotransmitters may be involved
• ## support for dopamine hypothesis - antipsychotics work by reducing dopamine activity