Biological Approah to explaining OCD Flashcards
Define genetic explanations and neural explanations
Genetic explanations - Genes are inherited and make up chromosomes that consist of DNA and code the physical and psychological functions of an organism.
Neural explanations - View that physical and psychological functions are determined by behaviour of the nervous system ie) brain and individual neurons.
Explain the genetic explanations
OCD is a disorder that is said to have a biological nature, as Lewis found in his study that 37% of his OCD patients had a parent with OCD and 21% had siblings with, so the genetic vulnerability for OCD is passed down and environmental triggers are needed for the OCD itself to become apparent.
Candidate genes - have been found that create a vulnerability for OCD ie) genes involved in regulating serotonin system/ 5TH1-D Beta- a gene implicated in efficiency of transporting serotonin across synapses.
OCD is Polygenic - Multiple genes are responsible for OCD, Taylor analysed studies and found over 230 genes may be responsible. Genes responsible are those to do with serotonin, and dopamine- our mood regulators.
Different types of OCD - OCD results due to different groups of genes in different people, so is aetiologically heterogeneous. There’s evidence to suggest different types of OCD are result of different genetic variations ie) religious obsession or hoarding.
Evaluate Genetic Explanations
Good supporting evidence - Twin studies show people can be born with a vulnerability to OCD, Nesdat reviewed twin studies and found 68% MZ twins shared OCD vs 31% DZ.
Too many Candidate genes - Very little value of genetic explanations because it barely provides predictability as many genes can be responsible and can only contribute to genetic vulnerability by a fraction.
Environmental risk factors- diathesis stress model- Cromer found over 1/2 OCD patients had traumatic past event and the more traumatic events they had, the worse the OCD. So, it doesn’t only have genetic origins.
Twin studies are flawed as genetic evidence - because fail to note MZ twins may have closer similarity in environment too , not just genes!
Explain neural explanations
Role of serotonin- Some cases of OCD can be explained by a reduction of serotonin system in the brain as it is a mood enhancer and when there are low levels mood-info transmission doesn’t take place as quickly enough.
Decision making systems- Some types of OCD, mainly hoarding system can be said to be due to impaired information processing as the lateral parts of the frontal lobes are abnormally functioning. Evidence also suggest the left parahippocampal gyrus is abnormally functioning (to do w/unpleasant thoughts).
Evaluate neural explanations
Some supporting evidence -Some antidepressants to treat OCD are focused solely on increasing serotonin levels, so shows neural explanation. Also, Nesdat says OCD is also formed in Parkinson’s Disease, which has a biological explanation, so OCD must too.
It’s unclear what neural mechanisms are involved- No neural system has been found to be consistently involved in OCD ie) Cavendini found that abnormal functioning decision making neurons in OCD are also apparent in decision making.
We shouldn’t assume neural mechanisms cause OCD- Cause and result can be mixed up as these abnormally functioning neurons may not necessarily be the cause of OCD, but can instead be the result.
Serotonin OCD link may simply be co-morbidity with depression- Many OCD sufferers have depression (co-morbidity ie)2 disorders). Depression can be explained by low serotonin levels too, so is it OCD explanation or depression explanation with patients who happen to have OCD?
