Biological Approach to Explaining OCD Flashcards
(15 cards)
1
Q
Lewis (1936):
A
- OCD patients 37% had parents with OCD and 21% had siblings with OCD.
- Suggests that OCD runs in families, although what is probably passed on from one generation to the next is genetic vulnerability not the certainty of OCD.
2
Q
Diathesis-Stress Model:
A
Certain genes leave some people more likely to suffer a mental disorder but it is not certain- some environmental stress is necessary to trigger the condition.
3
Q
Candidate Genes:
A
- Genes that create vulnerability for OCD.
- Some of these genes are involved are involved in regulating the development of the serotonin system.
- The gene 5HT1-D beta is implicated in the efficiency of transport of serotonin across synapses.
4
Q
OCD is polygenic
A
- Not caused by one single gene, but that several genes are involved.
- Taylor (2013) has analysed findings of previous studies and found evidence that up to 230 different genes may be involved in OCD.
- Genes that have been studied in relation to OCD include those associated with the action of dopamine as well as serotinin, both neurotransmitters believed to have a role in regulating mood.
5
Q
Different types of OCD
A
- One group of genes may cause OCD in one person but a different group of genes may cause the disorder in another person.
- The term used to describe this is aetiologically heterogenous, meaning that the origin of OCD has different causes.
- Some evidence to suggest that different types of OCD may be the result of particular genetic variations, like hoarding disorder and religious obsession.
6
Q
Neural Explanations: Role of Serotonin
A
- Serotonin is believed to help regulate mood.
- Neurotransmitters are responsible for relaying information from one neuron to another.
- If a person has low levels of serotonin then normal transmission of mood-relevant information does not take place and mood- and sometimes other mental processes- are affected.
- Some cases of OCD may be explained by a reduction in the functioning of the serotonin system in the brain.
7
Q
Neural explanations: Decision-Making System
A
- Some cases of OCD seem to be associated with impaired decision making.
- May be associated with abnormal functioning of the lateral of the frontal lobes of the brain.
- The frontal lobes of the front part of the brain that are responsible for logical thinking and making decisions.
- Evidence that an area called the left parahippocampal gyrus, associated with processing unpleasant emotions, functions abnormally in OCD.
8
Q
E: Supporting Evidence (GE)
A
- Variety of sources for idea that some people are vulnerable to OCD as a result of their genetic makeup.
- One of the best sources of evidence for the importance of genes is twin studies.
- Nestadt et al. 2010 reviewed previous twins studies and found that 68% of identical twins shared OCD as opposed to 31% of non-identical twins.
- Suggests a genetic influence on OCD.
9
Q
E: Too Many Candidates Genes (GE)
A
- Twins studies strongly suggest that OCD is largely under genetic control, psychologists have been much less successful at pinning down all the genes involved.
- Appears that several genes are onvolved and that each genetic variation only increases the risk of OCD by a fraction.
- Genetic explanation is unlikely to ever be very useful because it provides very little predictive value.
10
Q
E: Environmental Risk Factors (GE)
A
- It seems that environmental risk factors can also trigger or increase the risk of developing OCD (diathesis-stress model).
- Cromer et al. (2007) found that over half the OCD patients in their sample had a traumatic event in their past, and that OCD was more severe in those with more than one trauma.
- OCD cannot be entirely genetic in origin, at least not in all cases. It may be more productive to focus on the environmental causes because we are able to be something about those.
11
Q
E: Some supporting evidence (NE)
A
- Evidence to support some neural mechanisms in OCD. Some antidepressants work purely on the serotnin system, increasing levels of this neurotransmitter.
- Such drugs are effective in reducing OCD symptoms and this suggests that the serotonin system is involved in OCD.
- OCD symptoms form a part a part of a number of other conditions that are biological in origin, Parkinson’s Disease (Nestadst).
- Biological processes that cause the symptoms in those conditions may be also be responsible for OCD.
12
Q
E: Not clear what neural mechanisms are involved (NE)
A
- Studies of decision making have shown that these neural systems are the same systems that function abnormally in OCD (Cavedini et al.2002).
- However, research has also identified other brain systems that may be involved sometimes but no system has been found that always plays a role in OCD.
- We cannot really claim to understand the neural mechanisms involved in OCD.
13
Q
E: Not assume the neural mechanisms cause OCD
A
- There is evidence to suggest that various neurotransmitters and structures of the brain do not function normally in patients with OCD.
- Not the same as saying that this abnormal functioning causes the OCD.
- Biological abnormalities could be a result of OCD rather than its cause.
14
Q
E: Serotonin-OCD link may be simply co-morbidity
A
- Many people who suffer OCD become depressed. Having 2 disorders together is called co-morbidity.
- This depression probably involves (though is not necessarily caused by) disruption to the serotonin system.
- Leaves the logical problem when it comes to the serotonin system as a possible basis for OCD. Simply be that the serotonin system is disrupted in many patients with OCD because they are depressed as well.
15
Q
E: Twin Studies are Flawed as Genetic Evidence
A
- Twin studies are a standard source of evidence for genetic influence.
- They make the assumption that identical twins are only more similar than non-identical twins in terms of their genes, but overlook the fact that identical twins may also be similar in terms if shared environment.
