biological explanations Flashcards
Genetics
DNA impacting psychological features - transmitted from parents
Neural correlates
Patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience
Dopamine
A neurotransmitter that generally has an excitatory effect and is linked to the sensation of pleasure
- Unusually high levels are associated with schizophrenia and unusually low levels are associated with Parkinson’s disease
Twin studies
People with schizophrenia often have relatives with the disorder
MZ twins have higher concordance rates - 48% than DZ twins - 17%, general population is 1%
Candidate genes
Individual genes that may be associated with increased risk of schizophrenia eg genes coding for functioning of neurotransmitters including dopamine
The role of mutation
Parental DNA may mutate because of radiation, virus, ect
- Explains schizophrenia when no family history
EVAL - research support
P - strength as strong evidence base
E - family studies show risk increases with genetic similarity, adoption studies who biological children with parents with schizophrenia are heightened risk even if they grow up in an adoptive family
E - recent twin study by Rikke Hilker et al showed a concordance rate of 33% of identical twins and 7% for non-identical twins
L - shows people are more vulnerable to schizophrenia as a result of their genetic make-up
EVAL - environmental factors
P - limitation of genetic explanation is clear evidence of environmental influence
E - include both biological and psychological influences - biological risk factors include birth complications and smoking THC-rich cannabis in teenage years - psychological risk factors eg childhood trauma leaves people more vulnerable
E - 67% of people with schizophrenia and related psychotic disorders reported at least one childhood trauma as opposed to 38% of matched group with non-psychotic mental health issues
L - genetic factors alone cannot provide a complete explanation for schizophrenia
EVAL - genetic counselling
P - application of understanding is genetic counselling
E - if one or more potential parents have a relative with schizophrenia, they risk having a child who would go on to develop the condition
E - however the risk estimate provided by genetic counselling is just an average figure
L - it will not really reflect the probability of a particular child going on to develop schizophrenia because they will experience a particular environment which also has risk factors
Neural correlates of schizophrenia
Research has identified some neural correlates ie brain structure or function
- Best-known neural correlate of schizophrenia is the neurotransmitter dopamine
brain structure/neurotransmitter associated with behaviour ie symptoms
Original dopamine hypothesis
High levels/activity of dopamine (hyperdopaminergia) in subcortical brain areas
- Based on discovery that drugs used to treat schizophrenia caused symptoms similar to those with parkinson’s
Updated version
Abnormally low dopamine levels/activity (hypodopaminergia) in brain’s cortex leads to hyperdopaminergia in subcortical areas
- Davis et al - cortical hypodopaminergia
EVAL - evidence for dopamine
P - strength as support for idea
E - amphetamines increase DA and worsen symptoms in people with schizophrenia and induce symptoms in people without
E - antipsychotic drugs reduce DA activity and reduce the intensity of symptoms - some candidate genes act on the production of DA or DA receptors
L - strongly suggests that dopamine involved in the symptoms of schizophrenia
EVAL - glutamate
P - limitation as evidence for central role of glutamate
E - post-mortem and live scanning studies have consistently found raise levels of neurotransmitter glutamate in several brain regions of people with schizophrenia
E - several candidate genes for schizophrenia are believed to be involved in glutamate production or processing
L - equally strong case can be made for role of other neurotransmitters
EVAL - amphetamine psychosis
P - Catherine Tenn et al - induced schizophrenia-like symptoms in rats using amphetamines
E - Relieved symptoms using drugs that reduce DA action - this supports the dopamine hypothesis
E - however, other drugs that also increase DA levels do not cause schizophrenia-like symptoms
L - Garson has challenged the idea that amphetamine psychosis closely mimics schizophrenia
