Biological Explanations For Schizophrenia* Flashcards
How does the risk of schizophrenia change with genetic similarity to a relative?
Increases with genetic similarity:
* 2% if an aunt has it
* 9% if a sibling has it
* 48% if an identical twin has it
Gottesman conducted a large-scale family study demonstrating these statistics.
What is the term for the involvement of multiple genes in the risk of schizophrenia?
Polygenic
Early research aimed to find a single faulty gene but it was later established that multiple genes are involved.
Which neurotransmitter is most commonly associated with schizophrenia?
Dopamine
Most likely genes involved in schizophrenia are those encoding for neurotransmitters including dopamine.
What did Ripke et al’s study reveal about genetic variations associated with schizophrenia?
108 separate genetic variations were associated with increased risk of schizophrenia
The study compared the genetic makeup of 37,000 schizophrenics to 113,000 controls.
What role do mutations play in the appearance of schizophrenia in families with no prior history?
Mutations can arise from radiation, poison, and infection
Positive correlation exists between paternal age and risk of schizophrenia.
What is the best-known neural correlate of schizophrenia?
Dopamine
Dopamine is important in the functioning of several brain systems related to the symptoms of schizophrenia.
What does the original dopamine hypothesis suggest about dopamine levels in schizophrenia?
Higher levels of dopamine in the sub cortex
The hypothesis is based on the discovery that antipsychotics can cause Parkinson’s-like symptoms.
What is hypERdopaminergia?
Excess of dopamine levels
This is thought to be related to symptoms of schizophrenia, particularly in Broca’s area.
What does the updated version of the dopamine hypothesis propose?
Involvement of both high and low levels of dopamine in different brain regions
It suggests that low dopamine in the prefrontal cortex could explain negative symptoms of schizophrenia.
What evidence supports the genetic explanation for schizophrenia?
Strong evidence from family studies
* Gottesman’s study
* Tienari et al’s findings on biological children
* Hilker et al’s concordance rates
These studies indicate that some individuals are more vulnerable due to genetic factors.
What environmental factors could contribute to schizophrenia?
Psychological influences such as:
* Traumatic birth
* THC-rich cannabis use in teen years
* Childhood trauma
67% of individuals with schizophrenia reported at least one childhood trauma.
What evidence supports the involvement of dopamine in schizophrenia?
Amphetamines increase dopamine and worsen symptoms
* Antipsychotics reduce dopamine activity
* Some candidate genes affect dopamine production
These findings suggest a strong link between dopamine and schizophrenia symptoms.
What limitation exists in the dopamine hypothesis regarding other neurotransmitters?
Evidence for a central role of glutamate
Post-mortem studies have shown higher levels of glutamate in various brain regions of those with schizophrenia.
What is the effect of amphetamines on individuals without schizophrenia?
They induce schizophrenic symptoms
These symptoms disappear when the individual stops taking amphetamines.
What is the function of antipsychotic drugs in relation to dopamine?
Block dopamine activity
They reduce positive symptoms and are classified as dopamine antagonists.
