Psychopathology - Biological approach Flashcards
What are the two biological explanations of OCD?
Genetics
Neural explanations
What studies support genetics as a biological explanation of OCD?
Lewis - 1936 - Studied patients with OCD - 37% had parents with OCD - 21% had siblings with OCD In conclusion, there is a genetic basis to the disorder.
Nestadt - 2010
- Twin study studying MZ and DZ twins
- MZ had 68% concordance rate
- DZ had 31% concordance rate
In conclusion, there is a genetic basis to OCD because MZ twins who share more DNA have a much higher concordance rate than DZ twins.
However, it is also evidence that there is an environmental influence on development on OCD because if it was purely genetic, MZ concordance rate would be 100%.
What is the strength and weakness of family and twin studies?
Strength - There is evidence to suggest that there is a genetic component to OCD. Twin studies are one of the best sources of evidence.
Weakness - Family studies could also be used as evidence of environmental and genetic factors.
What is the strength and weaknesses of candidate genes?
Strength - research has implicated a number of candidate genes in the development of OCD.
Weakness - There are many genes involved and there may be more yet to be identified.
Weakness - each genetic variation only increases the risk of OCD by small fraction so it lacks predictability.
What is the strength and weakness of the interaction of genes and environmental factors?
Strength - Research supports that individuals may have a genetic vulnerability towards OCD that is triggered by an environmental stressor.
Weakness - Cromer found that over half of the OCD patients in their sample had a traumatic event in the past. This means that environment is very important in explaining OCD. It may be better to focus on environmental rather than biological explanation as we may be able to change the environment.
What does the basal ganglia control?
Repetitive movement
What does the orbitofrontal cortex control?
Worry
What does the thalamus control?
Safety behaviours
What evidence is there that serotonin plays a role in OCD?
Low levels are associated with OCD because SSRI medications, which increase the activity of serotonin at the synapses of the brain, are effective at improving OCD symptoms in many cases.
How does SSRI work?
Selective serotonin reuptake inhibitor targets serotonin and blocks the reuptake channel so serotonin remains in the cleft for longer, and can continue to deliver its message at the receptor sites. It amplifies the serotonin message so that many people taking SSRI uptain some relief from taking it.
They are effective for 70% of patients.
What are the strengths of brain function as a neural explanation for OCD?
Advanced technology has allowed accurate investigation - OCD sufferers do seem to have hyperactivity in parts of the brain.
We know cleaning and checking behaviours are hard wired in the thalamus where there is hyperactivity.
What are the weaknesses of brain function as a neural explanation for OCD?
Repetitive acts may be explained by the abnormality of the basal ganglia but this doesn’t explain obsessional thoughts.
No area has been found that always plays a role in OCD.
Neural changes could be as a result of suffering from the disorder not necessarily the cause of it.
What is the strength of the role of neurotransmitters as a neural explanation?
It allows medication to be developed which helps many sufferers.
What are the weaknesses of the role of neurotransmitters as a neural explanation?
Drugs are not completely effective so neurotransmitters are not the only cause of OCD.
Just because administering SSRIs decrease OCD symptoms it does not mean that this was the cause in the first place.
What other drugs are used in treatment of OCD other than SSRIs?
Trycyclics - also alter amount of serotonin at the synapses in the brain but have more side effects and are fatal if overdosed - not recommended for patients also experiencing depression.
Antipsychotic medication - have unpleasant side effects and are used when other treatments do not work.
