Schizophrenia - Biological Flashcards
What are family studies?
Gotessman’s rule
Closer the biological the link the more likely you are to also develop the disorder
First degree relatives share 50% of DNA
Second degree relatives share 25% of DNA
Look at concordance rates
What are the three types of study used when researching the genetic explanation of schizophrenia?
Family studies
Twin studies
Adoption studies
What are twin studies?
Compare concordance rates between MZ and DZ twins
MZ twins share 100% DNA
DZ twins share 50% DNA
Would expect concordance to be higher for MZ twins
What are adoption studies?
Separate genetics from environment
If an adopted child goes on to develop schizophrenia even if adopted away from schizophrenic parent it suggests there is a genetic link
Family studies key research
First degree relatives 18x more likely to develop schizophrenia than general population
First degree relatives have higher prevalence of personality disorders
Both parents - 46% chance
One parent - 16% chance
Sibling - 8% chance
Twin studies key research
MZ - 50%
DZ - 15%
MZ - 40%
DZ - 5.3%
Adoption studies key research
- 3% of adopted children with schizophrenic mother developed schizophrenia
- 1% of adopted children with non-schizophrenic mother developed schizophrenia
13% of biological relatives of adoptees with schizophrenia also had schizophrenia
2% of biological relatives of adoptees without schizophrenia had schizophrenia
Genetic explanations evaluation
Strong research support
Family studies are retrospective
Concordance is never 100%
Scientific rigour
Twin studies difficult to conduct
Twins more likely to be treated similarly
Twin studies do not all use same diagnostic criteria
Longitudinal studies
Adopted children reared apart for a reason
Twins share uterine environment
Diagnostic criteria constantly changing
What is the dopamine hypothesis?
Schizophrenia is caused by excessive levels of dopamine
Controls out movements and ability to experience pleasure and reward
If excessive can result in exaggerated movements, emotions, and sensations
How is the dopamine hypothesis tested?
Post mortems
PET scans
Pharmacological studies
How is dopamine thought to be involved in schizophrenia?
Excessive production and/or release from the pre-synaptic cell
Faulty re-uptake by the post-synaptic cell
Over-sensitivity of dopamine receptors on the post-synaptic cell
Evaluation of neurochemical explanations of schizophrenia
Research support on effects of different drugs
Correlational data
Effect of other neurotransmitters
Speed of drugs vs speed of symptom change
Post mortem and PET scan research support
Scientific rigour
Use of meta-analysis
Reductionism/determinism
What are typical antipsychotics?
Phenothiazines introduced in 1952
Work by blocking dopamine receptors on the post synaptic cell
Prevent dopamine from binding to the receptors
Links to dopamine hypothesis
Reduce acute positive symptoms
Often a marked improvement in cognitive and behavioural function
Maximum benefits within first six months
Side effects
What are the side effects of typical antipsychotics?
Increased heart rate Tremors Weight gain Blurred vision Tar dive dyskinesia
What are atypical antipsychotics?
Introduced in 1990
Work temporarily on dopamine by blocking receptors, but also work at reducing serotonin function
Work on a wider range of symptoms
Clozapine particularly effective for those who have proved resistant to other neuroleptics
Side effects
