The Biological Approach to Explaining OCD Flashcards
What was Aubrey Lewis’ study into genetic vulnerability?
He observed that out of all his OCD patients, 37% had parents with OCD and 21% had siblings with OCD. This suggests that it runs in the family, although what is passed down is likely just the vulnerability, not the OCD itself.
What is the diathesis-stress model?
Certain genes leave people more likely to develop a mental disorder but it still is not certain. Some environmental stress is necessary to trigger the condition.
What are the candidate genes implicated in OCD?
The 5HT1-D beta gene is implicated in the transport of serotonin across synapses.
The COMT gene is also implicated in this.
What did Stephen Taylor find about OCD being polygenic?
OCD is connected by up to 230 different genes. Genes that have been studied include those associated with serotonin and dopamine, both of which play a role in regulating mood.
What does aetiologically heterogenous mean?
That there are many different groups of genes that can cause OCD, meaning the origin varies from person to person.
What is the role of serotonin in OCD?
Serotonin regulates mood, so if a person has low levels of serotonin then normal transmission of mood-relevant information does not take place and a person may experience low moods. At least some cases of OCD may be explained by this.
What is the role of decision-making systems in OCD?
Some cases, hoarding disorder in particular, are associated with impaired decision-making. This may be associated with the abnormal functioning of the lateral frontal lobes. These are responsible for logical thinking and decision-making. There is also evidence to suggest that the left parahippocampal gyrus, associated with processing unpleasant emotions, functions abnormally in those with OCD.
What is the strength for the genetic explanation of OCD?
The strong evidence base - Nestadt found 68% of identical twins shared OCD as opposed to 31% of non-identical twins.
What is the limitation of the genetic explanation of OCD?
There are environmental risk factors. There is strong evidence that genetic variation can make a person more or less vulnerable, however it does not seem to be entirely genetic and environmental factors can trigger it. Cromer found over half of her OCD clients had experienced a traumatic event in the past.
What is the strength of the neural correlates explanation of OCD?
Supporting evidence - Antidepressants that work purely on serotonin are effective - serotonin may be involved. OCD symptoms form part of conditions known to be biological, such as Parkinsons so if a biological disorder produces OCD symptoms then we an assume biological processes underlie OCD.
What is the limitation - no unique neural system?
One limitation is that the serotonin-OCD link may not be exclusive to OCD. Many people also experience clinical depression - this is called co-morbidity. This depression probably also involves serotonin, so we have an issue with serotonin as a possible basis - it is possible serotonin levels influence depression which comes alongside OCD.
