4.2 Biological and Psychological Explanations for Schizophrenia Flashcards
What is neural correlates?
Patterns of structure/activity in the brain that occur in coexistence with an experience (may be implicated in the experiences origins)
e.g dopamine in schizophrenia
What is dopamine?
A neurotransmitter with an excitatory effect, linked to the sensation of pleasure
What are the 3 genetic explanations of schizophrenia?
- Family studies
- Candidate genes
- The role of mutation
What have family studies shown about the risk of schizophrenia?
Confirm that the risk of schizophrenia increases in line with genetic similarity
What is a candidate gene?
A gene that is associated with the development of a particular disorder/condition
Why is schizophrenia polygenic and aetiologically heterogenous?
- Polygenic: involves a number of different genes
- Aetiologically heterogenous: a different combination of factors e.g genetic variations lead to the condition
Describe Ripke et al (2014) study into candidate genes
- Combined previous data from genome wide studies of schizophrenia
- Genetic make-up of 37,000 schizophrenics compared to control of 113,000 people
- 108 separate genetic variations associated with increased risk of schizophrenia
What is the role of mutation in schizophrenia?
The absence of a family history of the disorder may indicate a genetic origin of schizophrenia
What did Brown et al (2002) research show about the role of mutation in schizophrenia?
- Positive correlations between paternal age (increased risk of sperm mutation) and risk of schizophrenia
- Increases risk from 0.7% in under 25 to 2% in fathers over 50
Describe the original dopamine hypothesis
- Drugs used to treat schizophrenia (antipsychotics) reduce DA
- Therefore, schizophrenia a result of high DA levels
- E.g excess of DA receptors may explain schizophrenia symptoms e.g speech poverty
Describe the updated version of the dopamine hypothesis
- Addition of cortical hypodopaminergia (abnormally low DA in brain cortex)
- E.g low DA in prefrontal cortex (responsible for thinking) can explain cognitive problems
- Cortical hypodopaminergia leads to subcortical hyperdopaminergia (both high and low levels are influences in schizophrenia)
AO3 for genetic basis of schizophrenia
1. Research support: family studies e.g Gottesman shows risk increases with genetic similarity, Tienari et al (2004) adoption study biological children of parents with schizophrenia are at heightened risk if raised in adoptive family, twin study by Hilker et al (2018) showed concordance rate of 33% in identical and 7% in non-identical twins
2. Environmental factors: include both biological and psychological influences, biological = birth complications, smoking THC-rich cannabis in teenage years, psychological = childhood trauma (increases vulnerability to mental disorders), Morkved et al (2017) 67% of those with schizophrenia reported at least one childhood trauma compared to 38% for matched control group
AO3 for neural correlates of schizophrenia
1. Evidence for dopamine: Curren et al (2004) amphetamines increase DA and worsen schizophrenia symptoms/induce symptoms in those without, ALSO antipsychotic drugs reduce DA activity and increase symptom intensity, ALSO some candidate genes act on the production of DA/DA receptors
2. Glutamate: post-mortem/live scanning studies consistently found raised levels of neurotransmitter glutamate in several brain regions of those with schizophrenia, ALSO several candidate genes for schizophrenia involved in glutamate production/processing, strong evidence for the role of neurotransmitters
Who proposed the updated version of the dopamine hypothesis?
Davis et al
What did Howe et al state about the origins of abnormal DA function?
Genetic variations and early experiences of stress (psychological and physical) make people more sensitive to cortical hypodopaminergia and subcortical hyperdopaminergia
