Biological Explanations Of OCD Flashcards
Genetic explanations - candidate genes e.g 5HT1-D beta
Candidate genes -
Specific genes which create a vulnerability for OCD:
Serotonin genes - e.g. 5HT1-D beta are implicated in the transmission of serotonin across synapses
Dopamine genes - also implicated in OCD
Both the dopamine + serotonin neurotransmitters have a role in regulating mood
Genetic explanations- OCD is polygenic
OCD is caused by several genes rather than 1
Taylor (2013) found there may be up to 230 genes involved in OCD
Genetic explanations- different types of OCD
Different gene groupings can cause OCD in different people - it is not the same gene combination that causes OCD every time - meaning OCD is aetologically heterogeneous.
Evidence also suggests that different genetic variations may cause different types of OCD - such as hoarding disorder or religious obsession
Neural explanations - Low levels of serotonin lower mood
Neurotransmitters relay information between neurons.
Since serotonin is implicated in mood - if someone has low levels - then normal transmission of mood-relevant information cannot occur - and the mood will be affected.
Neural explanations- impairment of decision-making systems in frontal lobes.
Some OCD cases e.g. Hoarding disorder appear to be related to impaired decision-making.
The frontal lobes of the brain are responsible for logic and decision-making - so the impaired decision-making seen in OCD could be related to abnormal functioning in the frontal lobes.
Neural explanations- Parahippocampal gyrus dysfunction
Evidence also suggests that this area - associated with the processing of unpleasant emotions - is implicated in OCD - since abnormal functioning here seems to co-occur frequently with OCD
✅AO3- genetic explanation has good supporting evidence
Wide base of evidence supports idea of a vulnerability to OCD being present in some people as a result of genetic makeup
Nestadt et al (2010) reviewed twin studies - found 68% of MZ twins shared OCD compared to only 31% of DZ twins.
This research strongly supports an influence of genetics on OCD.
However, anything but 100% concordance in MZ twins tells us that OCD cannot have a solely genetic basis.
❌AO3- genetic explanations- too many candidate genes
Psychologists have had difficulty identifying all the genes involved in OCD.
This is because the polygenic nature of OCD means that each genetic variation only increases the risk of OCD by a fractional amount.
Failure to identify the specific genes is a weakness for the biological explanation- as it is unlikely to ever be very useful since it doesn’t have any predictive value.
❌AO3- environmental risk factors are also involved
Cromer et al (2007)
Found that over half of OCD patients from their sample had experienced severe trauma in their pasts - and generally, the more traumatic events someone had experienced, the worse the severity of their OCD.
Supports the diathesis-stress model. As well as this - focusing on environmental influences is far more useful as we are actually able to do something about these.
✅AO3- some supporting evidence for neural explanations
Antidepressants that solely affect the serotonin system have been seen to be effective in reducing OCD symptoms - supporting the notion that the serotonin system is active in OCD.
Further, in biological conditions such as Parkinson’s Disease - sufferers are seen displaying the same symptoms associated with OCD patients.
This could suggest that the biological systems that cause these Parkinson’s symptoms may also be responsible for OCD.
❌AO3- serotonin-OCD link may not be exclusive to OCD.
Many OCD sufferers have co-morbid depression.
Depression is believed to involve disruption to the serotonin system because of serotonin’s implications in mood.
This is a weakness as it could be that many OCD patients suffer disruption to the serotonin system but this is associated with co-morbid depression rather than OCD.
