Biological explanations of SZ Flashcards
Outline the genetic basis of SZ.
Biological characteristics are inherited from parents, so therefore conditions such as SZ could be inherited.
What genes contribute to the development of SZ?
Candidate genes.
Define polygenic.
More than one gene involved.
SZ is polygenic.
Give an example of a candidate gene?
COMT gene.
What does the COMT gene do?
Increases dopamine, and increased dopamine has been linked to hallucinations.
Give supporting evidence from twin studies for the role of genetic basis of SZ.
Gottesman- conducted a meta analysis and reviewed over 40 twin studies. The average concordance rate was 48% for MZ twins and 17% for DZ twins.
This suggests that SZ is likely to be, partly genetic.
Give limitations of the genetic basis of SZ.
-SZ is too biologically deterministic.
This genetic explanation ignores other possible contributing factors (e.g. free will).
-Methodological concerns with twin studies.
They not only share genetics but share similar environmental influences. (Nature or Nurture?)
Give an advantage of the genetic basis of SZ.
+Supporting evidence from Joseph (2004).
The concordance rate for MZ twins was higher than it was for DZ twins.
However, the concordance rate for MZ twins was not near 100%, suggesting genetics are not the sole cause of SZ.
What does the dopamine hypothesis suggest?
Suggests that abnormalities in these dopamine systems are responsible for causing SZ.
Explain hyperdopaminergia.
-Suggested that an increase in dopamine activity in the subcortex of the brain leads to positive symptoms of SZ.
What is one cause for the dopamine overactivity?
Abnormally high levels of D2 receptors.
If this occurs in Broca’s area it may lead to hallucinations and speech difficulties.
Explain hypodopaminergic.
Decrease in dopamine activity in the cortex has been linked to negative symptoms of SZ (avolition, speech poverty).
Decreased dopamine in the prefrontal cortex can be linked to the unusual cognitive functioning of patients with SZ.
Give 2 advantages of the dopamine hypothesis.
+Supporting evidence, studying the effects of drugs on symptoms of SZ.
Antipsychotic drugs have an antagonistic effect (reduce dopamine levels). Suggests high dopamine is linked to SZ.
+Has real life applications.
Psychoactive drugs alter levels of dopamine. Treatments are effective also, therefore have positive implications for the economy.
Give 2 disadvantages of the dopamine hypothesis.
-Inconclusive or contradictory evidence for the dopamine hypothesis.
Noll (2009) found that antipsychotic drugs only work in 1/3 of cases. Suggests that other neurotransmitters may be involved, not just dopamine.
-Too biologically reductionist.
potentially other neurotransmitters that are possibly involved in causing SZ.
What does the neural correlates theory suggest causes SZ?
Abnormalities in structural or functional features of the brain may be linked to SZ.
