Biological Explanations Flashcards
Describe Gottesman’s research into the genetic basis of schizophrenia
Large scale family study
Someone with an aunt who had schizophrenia has a 2% chance of getting it. Increased to 9% if it is a sibling. Up to 48% if MZ twin. (Correlation)
Explain candidate genes and schizophrenia
Appears schizophrenia is polygenic. Most Likely the genes that code for a neurotransmitter.
Describe Ripke et al research into genes and schizophrenia
Combined previous data from genome wide studies. Genetic makeup of 37000 people with it and 113000 controls.
108 separate genetic variations associated with schizophrenia (aetiologically heterogenous)
Describe the role of mutation and schizophrenia.
Mutation of parental DNA due to radiation, poison or viral.
Evidence of a positive correlation between paternal age and risk.
0.7% risk for fathers having children under 25
2% risk for fathers having children over 50
One strength of genetic evidence is research support (AO3)
Grottoeman: showed risk increased with similarity to a family member with it.
Tirenari et al: biological children of parents with it are at a heightened risk even if grow up with adoptive family.
Hilker et al: concordance rate of 33% for MZ and 7% for DZ twins.
One limitation of genetic evidence for schizophrenia is the environment (AO3)
Clear evidence to show environment increases risk of developing schizophrenia
Biological risk factors: smoking rich THC cannabis at a young age
Psychological risk factors: childhood trauma which leave people more vulnerable to adult mental health (with childhood trauma 67%, 38% with controls)
What is the original dopamine hypothesis based on? (And explain this)
Based on discovery that drugs are used to treat schizophrenia (antipsychotics which reduce dopamine). Caused symptoms similar to Parkinson’s (low DA) —> schizophrenia could be concerned with high DA in sub cortical areas of the brain eg. Excess DA receptors in Broca’s area, speech poverty.
Who created the updated dopamine hypothesis?
Davis et al
Explain the updated dopamine hypothesis
Proposed cortical hypodomaminergia (low DA in brain cortex) could explain symptoms eg. Cognitive problems.
Both genetic and early experience of stress make some people more sensitive to cortical hypodominergia/ subcortical.
One strength of neural explanations is the evidence for dopamine (AO3)
1st- amphetamines increase DA and worsen symptoms in people with schizophrenia and induce it in people without schizophrenia.
2nd- antipsychotic drugs reduce DA activity and intensity of symptoms
3rd- some candidate genes act on production of DA or DA receptors
Strongly suggests DA involvement
One limitation of neural explanation is glutamine (AO3)
Post mortem and live scanning studies have constantly found raised levels of neurotransmitter glutamine, in several brain regions of PPS with schizophrenia (McClutchen et al)
Several candidate genes for schizophrenia are believed to be involved in glutamine production or processing. Strong case for neurotransmitter.
