Biological explanations for schizophrenia Flashcards
what is the AO1 for the Genetic Basis of Schizophrenia
- Systematic versions of family/twin studies can be used to show that Schizophrenia has biological roots.
- We can compare concordance rates in various first, second and third degree relatives to work out the likelihood that schizophrenia has genetic links.
what is the AO3 for the genetic basis of schizophrenia
- Irving Gottesman
- Tienari et al
expand on the +ve AO3 point, Irving Gottesman, for the Genetic Basis of Schizophrenia
- Looked at peoples genetic similarity, and how likely they were to develop schizophrenia - examined peoples historic data (medical reports etc) (counts as a twin study)
- The more genetically related you are to a person with schizophrenia, the higher the concordance rate, the more likely they are to develop schizophrenia
- Higher concordance rate → the more likely the biology explanation is correct
- Schizophrenia in population = 1%
expand on the +ve AO3 point, Tienari et al, for the Genetic Basis of Schizophrenia
- Tienari et al (2004) carried out longitudinal adoption studies in Finland and found that children with schizophrenic mothers were seven times more likely than controls to develop schizophrenia despite living, since birth, with adoptive parents who had NO mental health problems.
- Shows that genetics + nature is more powerful than nurture → supports the biological explanation
what is the AO1 for candidate genes
- Schizophrenia appears to be polygenic - a number of genes working in combination to cause it
- It also seems to be aeitiologically heterogenous in that different combinations of factors could be the cause
what is the +ve AO3 for candidate genes
- Ripke (2014)
- Compared the genetic makeup of 37,000 patients with Schizophrenia and 113,000 controls
- Found 108 separate genetic variations were associated with developing Schizophrenia
- These genes were largely linked to functioning of dopamine pathways within the brain
what is the AO1 for the dopamine hypothesis
- The neurotransmitter dopamine is believed to work differently in patients with S.
- There are two major theories proposing what is going wrong with this system:
- Hyperdopaminergia in the subcortex
- Hypodopaminergia in the pre-frontal cortex
what is hyperdopaminergia
- in the subcortex
- High levels of dopamine in the most central and oldest part of the brain
- An excess of dopamine receptors in Broca’s Area (speech) –> could explain ALOGIA, derailment, auditory hallucinations
what is hypodopaminergia
- in the pre-frontal cortex
- More recent research has pointed to the possibility of LOW levels of dopamine in parts of the neocortex.
- The prefrontal cortex is responsible for higher order brain processes such as decision making, thinking processes. –> This could explain symptoms such as avolition, cognitive disturbances
what is the AO3 point drug treatment
- Evidence for the dopamine hypothesis comes from two different types of drugs:
- DOPAMINE AGONISTS such as AMPHETAMINES which INCREASE dopamine
- ANTI-PSYCHOTICS or DOPAMINE ANTAGONISTS which BLOCK dopamine
The drugs work therefore it’s biological - When amphetamines are given to schizophrenic patients, their symptoms increase dramatically. They can even produce schizophrenic symptoms in HEALTHY individuals.
- Antipsychotic drugs have been shown to be effective in reducing the symptoms of S in hundreds of peer reviewed studies.
- The efficacy of these 2 types of drug lend support to the dopamine hypothesis.
- Both of these drugs work, given in the correct circumstance
However…
- We are working on the premise that it’s dopamine
- Some of the genes identified in Ripke’s study do not relate to dopamine pathways in any way.
- The neurotransmitter GLUTAMATE is now being investigated as an alternative biological explanation.
what is the AO1 for Neural correlates of Schizophrenia
- Neural correlates are investigations of which brain structures or brain functions correlate with which behaviour
- Both positive and negative symptoms of schizophrenia are associated with specific neural correlates (specific areas of the brain)
what is the AO3 point Research Support for Neural Correlates
The following areas were all found to be functioning differently in schizophrenic patients:
- Wernicke’s Area (speech) which would explain the auditory hallucinations
- Occipital lobe (vision) would explain the visual hallucinations
- Basal ganglia (movement) would explain psychomotor disturbances
- Ventral Striatum (motivation) would explain avoilition
