Schizophrenia: Biological Explanations Flashcards
(29 cards)
Name the two biological factors influencing schizophrenia
1) Genetic factors
2) The dopamine hypothesis
Name the three types of studies within genetic theory
1) Family studies
2) Twin studies
3) Adoption studies
Key reason for family studies in determining biological explanation?
Find individuals with SZ and determine whether their biological relatives are similarly affected more often than non-biological relatives.
What have family studies established?
SZ is more common among biological relatives; closer degree of genetic relation shows greater risk.
Family studies:
Concordance rate for children with two SZ parents compared to children with one SZ parent?
Two SZ parents: 46%
One SZ parent: 13%
What opportunity do twin studies offer?
Opportunity for researchers to investigate relative contributions of genetic and environmental influences.
Twin studies:
What would it mean if there were a higher concordance rate of SZ between monozygotic twins than dizygotic twins?
The greater concordance rate is due to genetic factors.
Who studied concordance rate of twins?
Joseph (2004)
What did Joseph (2003) find by pooling all twin study data prior to 2001 regarding concordance rates?
Concordance rate for monozygotic twins was 40.4%
Rate for dizygotic twins was 7.4%
What do adoption studies allow researchers to do?
To study genetically related individuals who have been reared apart; allows them to distinguish between genetic and environmental factors.
Who studied 164 adoptees with SZ mothers in Finland?
Tienari et al (2000)
What did Tienari et al (2000) find in his study of 164 adoptees with SZ biological mothers?
Adoptees with SZ mothers had 6.7% rate of diagnosis whereas the control group with healthy mothers only had rate of 2% diagnosis.
Genetic liability confirmed.
Evaluation: ☹️
Family studies: what has research shown that may be the main reason for schizophrenia to run in a family instead of genetics?
May be more to do with common rearing patterns or other factors that have nothing to do with heredity.
Evaluation: ☹️
Family studies: research on expressed emotion has shown what?
The negative emotional climate in some families may lead to stress beyond an individual’s already impaired coping mechanisms, leading to a SZ episode.
Evaluation: ☹️
Twin studies: what crucial assumption behind twin research may be wrong?
Assumption that the environments of monozygotic and dizygotic twins are equivalent.
Evaluation: ☹️
Twin studies: who pointed out that MZ twins are treated more similarly and share more similar environments than DZ twins?
What does this mean?
Joseph (2004)
There is reason to believe that the difference in concordance rates reflect nothing more than the environmental differences that distinguish the two types of twin.
Evaluation: ☹️
Adoption: what is the (false) general assumption of adoption studies?
Assumption that adoptees are not ‘selectively placed’ ie adoptive parents who adopt children with SZ mothers are no different than adoptive parents who adopt children with a normal background.
Evaluation: ☹️
Adoption: who pointed out that adoptees are likely to be selectively chosen by people who know their background?
Joseph (2004)
What is dopamine?
One of many neurotransmitters that operate the brain.
What does the dopamine hypothesis suggest about the role of dopamine in SZ?
Messages from neuroma transmit dopamine too easily and too often- leading to SZ characteristics.
What are the three main sources of evidence for the dopamine hypothesis?
1) amphetamines
2) antipsychotic drugs
3) Parkinson’s disease
How has the use of amphetamines highlighted the role of dopamine in SZ?
Amphetamines are dopamine agonists, stimulating nerve cells containing dopamine causing the synapse to be flooded with it. Large doses of the drug can cause characteristics such as hallucinations and delusions.
How has the role of antipsychotic drugs highlighted the role of dopamine in SZ?
These drugs are dopamine antagonists because they block dopamine activity; this leads to reduced or eliminated symptoms. This strengthens biological argument.
How has Parkinson’s disease research highlighted role of dopamine in SZ?
Low levels of dopamine activity found in people who suffer Parkinson’s disease, a degenerative neurological disorder. It was found that some people taking the drug ‘L-Dopa’ to raise levels of dopamine were developing SZ-like symptoms.
