Biological explanations of Schizophrenia Flashcards
What are the different areas that can be discussed
- genetic basis
- neural corralates
- original DA hypothesis
- updated DA hypothesis
What aspects make up genetic basis
- family studies
- candidate genes
- mutation
What is the research for the genetic basis
- Family studies - Gottesman 1991
- Finnish adoption study - Tiernari 1991
- candidate genes - Ripke et al 2014
- mutation - brown et al 2002
what research is there for neural correlates
- brain structure - Juckel et al 2006
Give research for the dopamine hypothesis
Researchers aren’t famous studies so names aren’t important.
Outline Gottesman 1991 findings
Gottesman conducted twin studies which had a concordance rate of 17% between DZ twins and 48% between MZ twins. This shows strong evidence that genetics are an important cause of SZ
monozygotic and dizygotic
Evaluate Gottesman 1991
- The problem with twin studies is that concordance rates are never 100%. This suggests that genetics are not the only factors.
e.g. hostile family relationships or environmental factors or drug abuse are important. - Another weakness is that MZ twins are rare and only 1% of them would be expected to have SZ. Therefore we must be cautious when drawing conclusions.
- Another weakness is that twins share an environment so it is difficult to determine what is due to genetics.
Outline Tienari 1991
Tienari 1991 was a Finnish adoption study which consisted of 2 groups.
group 1 - had 155 adopted children whose biological mother had SZ
group 2 - consisted of a matched group of adoptibe children with no family history of SZ.
Outline Tienari 1991 findings and conclusion
In group 1: 10% of children developed SZ.
In group 2: 1% of children developed SZ
This is strong evidence to suggest that genetics are important, but not a complete explination of the cause of SZ.
Describe what is meant by neural correlates
Neural correlates are patterns of structure or activity in the brain that occur in conjunction with an experience such as SZ and may be implicated in its origins. Both positive and negative symptoms have neural correlates.
Give an example of neural correlates of negative symptoms
avolition: loss of motivation → motivation involves anticipation of a reward → certain regions of the brain are associated with this e.g. ventral striatum. Therefore it follows that an abnormality of areas such as the ventral striatum may be involved in the development of avolition.
Give research to support neural correlates of negative symptoms
Juckel et al 2006
observed a negative correlation between activity levels in the ventral striatum and the severity of negative symptoms of SZ.
What is dopamine
dopamine is a neurotransmitter, associated with attention and motivation
Outline the original DA hypothesis
SZ has been linked to excess activity of dopamine in subcortical areas of the brain.
(Hyperdopaminergia)
Explain the original DA hypothesis
- High DA activity in subcortex associated with hallucinations and speech poverty.
- There is an excess of DA receptors in pathways linking subcortex to Broca’s area.
- May explain specific symptoms e.g. speech poverty / auditory hallucinations.