Schiz- bio explanations Flashcards
What did Ripke find
Reported 108 genetic variants that could mediate a vulnerability to the disorder, including variations on chromosome 8 and 11, and the C4 gene.
What does polygenic mean in relation to schiz
belief that no one gene is likely to be responsible for all cases of schizophrenia, but several genes are involved
What did Hong find
Found that a variation on the gene TPH was far more common with Chinese patients with schizophrenia (interestingly this codes for serotonin production).
What did Ripke find: Reported ___ genetic variants that could mediate a vulnerability to the disorder, including variations on chromosome _ and __, and the __ gene.
108
8
11
C4
What can a faulty variant on the C4 gene lead to
Hyper pruning
Where is the C4 gene found
Found at synapses in the central nervous system
What does the C4 gene do
Mediates the pruning of synapses that normally takes place during development.
What did Tienari et al do
completed an adoption study in Finland with over 164 adopted kids whose biological mothers had been diagnosed with schizophrenia. These were matched with kids whose biological mothers did not suffer from schizophrenia.
Who was the control group in Tienari’s study
kids whose biological mothers did not suffer from schizophrenia.
What did Tienari find
11 (7%) of the sample whose biological mothers had schizophrenia had also been diagnosed with the condition compared to just 4 (2%) from the control group.
What did Tierani’s study find__ (7%) of the sample whose biological mothers had schizophrenia had also been diagnosed with the condition compared to just _ (2%) from the control group.
11
4
What does Tierani’s study help to do
validate the idea that schizophrenia has a genetic component as the adopted children do not share environmental influences with their biological mothers and provides concurrent validity for the role of genes in schiz
What could be happening at a post synaptic level to account for elevated levels of dopamine in the surrounding brain cells?
1)Not enough dopamine could be being broken down after synaptic transmission, leaving too much dopamine in the surrounding cells.
2)Re-uptake processes may be impaired leaving to much dopamine in the synapse.
What two observations support the dopamine hypothesis
Drugs that increase dopamine production make symptoms of schizophrenia worse. Amphetamine based drugs (dopamine agonists) increase dopamine activity and can bring about symptoms of schizophrenia.
Higher than normal concentrations of dopamine have been found in the post-mortems of patients that suffered from schizophrenia
What did Grilly find which supports the dopamine hypothesis
People taking dopamine antagonists to raise the levels of dopamine in order to alleviate symptoms of parkinsons, were developing schiz like symptoms
What did Davis et al find that could explain negative symptoms of schiz
Pointed out that in the prefrontal cortex there are no D2 receptors and actually there appears to be a deficiency of dopamine in this region.
What is HYPO-dopaminergia
Low levels of dopamine
What is HYPER-dopaminergia
High levels of dopamine
Evaluation-incomplete research
P- concordance rate is not 100%
E- means that genetics cannot be soley to blame
E- there is something else e.g environment
L- genetic approach is incomplete
Bio chem explanations argue that schiz is caused by elevated levels of DA where?
At key synaptic sites within subcortical regions of the brain e.g the mesolimbic pathway and the limbic pathway
What is an excess of DA argued to cause
A sort of system overload where too many impulses are being transmitted (too much is happening)
This arguably triggers positive symptoms of schiz e.g delusions.
