Biological explanation Flashcards
What are genetics?
Inherited factors which make certain individuals more likely to develop a behaviour or mental disorder
What genetic factor has schizophrenia been linked to?
Polygenetic sets of candidate genes
What have family studies established?
That schizophrenia is more common among biological relatives of a person with schizophrenia
With regards to family studies, what increases the risk of schizophrenia?
The degree of genetic relatedness
What type of study did Gottesman conduct?
Family study
What concordance rate did Gottesman find when both parents had schizophrenia?
46%
What concordance rate did Gottesman find when one parent had schizophrenia?
13%
What concordance rate did Gottesman find when one sibling had schizophrenia?
9%
What do twin studies show?
A genetic link - but only when the concordance rate of MZ twins is higher than DZ twins
What type of study did Joseph conduct?
A twin study
What concordance rate did Joseph find for MZ twins?
40.4%
What concordance rate did Joseph find for DZ twins?
7.4%
What do adoption studies allow us to do?
Disentangle genes from environmental factors
What type of study did Tienari conduct?
An adoption study
How many Finnish adoptees took part in Tienari’s study?
164
What percentage of the adoptees in Tienari’s study developed schizophrenia?
6.7%
What percentage of the control group in Tienari’s study developed schizophrenia?
2%
What does the dopamine hypothesis claim?
That an excess of dopamine in certain brain regions is associated with positive symptoms
What are amphetamines?
Dopamine agonists
What happens when ‘normal’ individiduals are exposed to amphetamines?
They start displaying schizophrenia-like positive symptoms
What do antipsychotics do?
They block the activity of dopamine in the brain
What effect do antipsychotics have on individuals with schizophrenia?
It reduces their positive symptoms
What is hyperdopaminergia?
Too much dopamine
What is hypodopaminergia?
Too little dopamine
What can hyperdopaminergia in the subcortex cause?
Positive symptoms
What can hypodopaminergia in the prefrontal cortex?
Negative symptom
What hypothesis has been drawn about the cognitive symptoms of schizophrenia?
It’s the result of a deficit in the prefrontal cortex, and its connections with other brain regions like the hippocampus
What happens to the hippocampus in schizophrenic patients?
It undergoes anatomical changes
What happens to grey matter in schizophrenic patients?
The volume decreases
Where does the volume of grey matter decrease in schizophrenic patients?
Frontal + temporal lobes
What happens to white matter in schizophrenic patients?
They experience a decrease in the myelination of white matter pathways
What are the 4 AO3 points for the biological explanation of schizophrenia?
1) MZ twins encounter more similar environments
2) Treatment support for dopamine hypothesis
3) Adoptees may be selectively placed
4) Challenges to the dopamine hypothesis
What is the key assumption of twin studies?
MZ and DZ have an equal degree of shared environment
Which type of twins experience more similar shared environment?
MZ
What are MZ twins more likely to experience?
Identity confusion
Where does evidence for the dopamine hypothesis come from?
Successful treatments which aim to reduce dopamine levels in the brain
In the meta-analysis of studies into the use of antipsychotics, how many studies were included?
212
In the meta-analysis of studies into the use of antipsychotics, what was found?
Antipsychotics are more effective than placebos at reducing schizophrenia symptoms
What is a key assumption of adoption studies?
That adoptees are not selectively placed into families with particular backgrounds
What belief was there about children of schizophrenic mothers?
There was a belief that any child of a mother admitted to a psychiatric hospital would be feeble-minded, insane and degenerate
What did one study find about the adoptive placement of children of schizophrenic mothers?
It was highly unlikely they would be placed into families who had no history with schizophrenia
Why have psychologists claimed that both the original and revised dopamine hypothesis have limited explanatory power?
Because antipsychotics do not alleviate hallucinations + delusions in around ⅓ of people who suffer from them
