Schizophrenia- Biological explanations for schizophrenia Flashcards
Genetics -
Genes consist of DNA strands. DNA produces ‘instructions’ for general physical features of an organism (such as eye colour, height) and also specific physical features (such as neurotransmitter levels and size of brain structures). These may impact on psychological features (such as intelligence and mental disorder). Genes are transmitted from parents to offspring. i.e. inherited.
Dopamine -
A neurotransmitter that generally has an excitatory effect and is associated with the sensation of pleasure. Unusually high levels are associated with schizophrenia and unusually low levels are associated with Parkinson’s disease.
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.
What evidence suggests that schizophrenia runs in families?
Schizophrenia has been noted to run in families, suggesting a genetic link, though family members also share environments.
What is the relationship between genetic similarity and the risk of schizophrenia?
There is a strong relationship between the degree of genetic similarity and shared risk of schizophrenia, with higher genetic similarity correlating with higher risk.
What percentage of genes do identical twins share?
Identical twins share 100% of their genes.
What percentage of genes do siblings or parents share?
Siblings or parents share 50% of their genes.
What did Irving Gottesman’s (1991) family study show?
Gottesman’s study showed a strong relationship between genetic similarity and the likelihood of developing schizophrenia.
What are candidate genes in schizophrenia?
Candidate genes are individual genes believed to be associated with an increased risk of inheriting schizophrenia.
Is schizophrenia polygenic?
Yes, schizophrenia is polygenic, meaning multiple genes each confer a small increased risk.
What does it mean for schizophrenia to be aetiologically heterogeneous?
It means that different combinations of genetic factors can lead to the condition.
What did Stephen Ripke et al. (2014) find in their genome-wide study of schizophrenia?
They found 108 genetic variations associated with increased risk of schizophrenia, including genes related to dopamine functioning.
What is the dopamine hypothesis?
The dopamine hypothesis suggests that dopamine dysfunction in the brain is involved in schizophrenia.
What is hyperdopaminergia in the subcortex?
Hyperdopaminergia refers to high levels or activity of dopamine in the subcortex, which may be linked to symptoms like auditory hallucinations.
What is hypodopaminergia in the cortex?
Hypodopaminergia refers to low levels of dopamine in the prefrontal cortex, which may be linked to negative symptoms like poor decision-making.
What are neural correlates?
Neural correlates are measurements of brain structure or function that correlate with specific experiences, such as schizophrenia symptoms.
What neural correlate is associated with avolition?
Lower activity levels in the ventral striatum are a neural correlate of avolition, a negative symptom of schizophrenia.
What did Juckel et al. (2006) find about the ventral striatum and negative symptoms?
They found lower activity levels in the ventral striatum in people with schizophrenia, correlating with the severity of negative symptoms.
What neural correlates are associated with auditory hallucinations?
Reduced activity in the superior temporal gyrus and anterior cingulate gyrus is a neural correlate of auditory hallucinations.
What did Allen et al. (2007) find about brain activity during auditory hallucinations?
They found lower activation levels in the superior temporal gyrus and anterior cingulate gyrus in people experiencing auditory hallucinations.
What evidence supports genetic susceptibility to schizophrenia?
Evidence includes family studies like Gottesman (1991), adoption studies like Tienari et al. (2004), and molecular studies like Ripke et al. (2014).
What did Pekka Tienari et al. (2004) find in their adoption study?
They found that children of people with schizophrenia were at heightened risk even when adopted into families with no history of schizophrenia.
What is the role of dopamine agonists in schizophrenia?
Dopamine agonists, like amphetamines, worsen schizophrenia symptoms and can induce schizophrenia-like symptoms in non-diagnosed individuals.
How do antipsychotic drugs work in relation to dopamine?
Antipsychotic drugs reduce dopamine activity, supporting the role of dopamine in schizophrenia.
What did Lindstroem et al. (1999) find about dopamine production in schizophrenia?
They found that chemicals needed to produce dopamine are taken up faster in the brains of people with schizophrenia, suggesting higher dopamine production.
What is the limitation of the dopamine hypothesis?
The dopamine hypothesis does not fully explain schizophrenia, as other neurotransmitters like glutamate may also play a role.
What is the correlation-causation problem in neural correlates?
Neural correlates do not prove causation; unusual brain activity could be a cause, effect, or influenced by another factor.
What is the role of mutation in schizophrenia?
Mutations in parental DNA, such as in paternal sperm cells, can increase the risk of schizophrenia, even without a family history.
What did Brown et al. (2002) find about paternal age and schizophrenia risk?
They found a positive correlation between paternal age and schizophrenia risk, with risk increasing from 0.7% in fathers under 25 to over 2% in fathers over 50.
What is the role of the psychological environment in schizophrenia?
Psychological factors, such as family functioning during childhood, may play a role, as biological factors alone do not fully explain schizophrenia.
What does the probability of developing schizophrenia in identical twins suggest?
Even if one identical twin has schizophrenia, the other has less than a 50% chance of developing it, suggesting environmental factors also play a role.
What is the current focus of schizophrenia research beyond dopamine?
Research has shifted to exploring the role of other neurotransmitters, such as glutamate.
What does the mixed evidence for the dopamine hypothesis suggest?
It suggests that while dopamine is important, it is not the sole factor in schizophrenia, and other neurotransmitters are likely involved.
What does the existence of neural correlates tell us about schizophrenia?
Neural correlates highlight brain systems that may not function normally but do not definitively explain the cause of symptoms.
What is the significance of the Gottesman (1991) study?
It provides strong evidence for genetic vulnerability to schizophrenia by showing a clear relationship between genetic similarity and shared risk.
What does the Ripke et al. (2014) study suggest about schizophrenia genetics?
It suggests that schizophrenia involves multiple genetic variations, including those related to dopamine and other neurotransmitters.
What does the role of mutation in paternal sperm suggest about schizophrenia?
It supports the importance of genetic factors, as mutations in sperm can increase schizophrenia risk even without a family history.
What does the correlation between ventral striatum activity and negative symptoms suggest?
It suggests that reduced activity in the ventral striatum may be linked to negative symptoms, but the exact causal relationship is unclear.
What does the evidence for genetic and environmental factors suggest about schizophrenia?
It suggests that schizophrenia results from a combination of genetic susceptibility and environmental influences.
What does the overemphasis on dopamine in schizophrenia research overlook?
It overlooks the potential role of other neurotransmitters and environmental factors in the development of schizophrenia.
What does the study by Allen et al. (2007) suggest about auditory hallucinations?
It suggests that reduced activity in the superior temporal gyrus and anterior cingulate gyrus is associated with auditory hallucinations.
What does the study by Juckel et al. (2006) suggest about negative symptoms?
It suggests that lower activity in the ventral striatum is associated with the severity of negative symptoms like avolition.
What does the evidence from drug studies suggest about dopamine and schizophrenia?
Drug studies suggest that dopamine plays a significant role, as dopamine agonists worsen symptoms and antipsychotics reduce dopamine activity.
What does the correlation between paternal age and schizophrenia risk suggest?
It suggests that mutations in paternal sperm, which increase with age, may contribute to the risk of schizophrenia.
What does the role of glutamate in schizophrenia research indicate?
It indicates that dopamine is not the only neurotransmitter involved, and glutamate may also play a significant role.
What does the evidence from adoption studies suggest about schizophrenia?
Adoption studies suggest that genetic factors are significant, as children of people with schizophrenia remain at higher risk even when raised in unaffected families.
What does the mixed evidence for the dopamine hypothesis imply for treatment?
It implies that treatments targeting dopamine may not be sufficient, and other neurotransmitter systems should also be considered.
What does the correlation-causation problem imply about neural correlates?
It implies that while neural correlates are useful for identifying brain abnormalities, they do not necessarily explain the cause of schizophrenia symptoms.
What does the role of psychological factors suggest about schizophrenia?
It suggests that while biological factors are important, psychological and environmental factors also contribute to the development of schizophrenia.
What does the evidence for genetic susceptibility and environmental factors suggest about schizophrenia?
It suggests that schizophrenia is a complex condition influenced by both genetic vulnerability and environmental triggers.
