The biological approach to explaining OCD Flashcards
(12 cards)
What is the Biological approach
A perspective that emphasises the importance of physical processes in the body such as
genetic inheritance and neural function.
What are Genetic explanations (3)
- Genes make up chromosomes and consist of DNA which codes the physical features of an organism (such as eye colour, height)
and psychological features (such as mental disorder, intelligence). - Genes are inherited from parents
What are candidate genes (3)
- Genes which create vulnerability for OCD
- Some of these genes are involved in regulating the development of the serotonin system.
- For example, the gene 5HT1-D beta is implicated in the efficiency of transport of serotonin across synapses.
OCD is polygenic
However, like many conditions, OCD seems to be polygenic. This means that OCD is
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
serotonin, both neurotransmitters believed to have a role in regulating mood.
Different types of OCD
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 heterogeneous, meaning that the origin (aetiology) of OCD has
different causes (heterogeneous).
There is also some evidence to suggest that different types of OCD may be
the result of particular genetic variations, such as hoarding disorder and religious
obsession.
What does it mean by ‘OCD is polygenic’ (3)
- OCD is not caused by one single gene but 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 serotonin, both neurotransmitters believed to have a role in regulating mood.
What are the Different types of OCD (3)
- 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 heterogeneous, meaning that the origin (aetiology) of OCD has different causes (heterogeneous).
- There is also some evidence to suggest that different types of OCD may be the result of particular genetic variations, such as hoarding disorder and religious obsession.
What are Neural explanations (2)
- The view that physical and psychological characteristics are determined by the behaviour of the nervous system
- In particular the brain as well as individual neurons.
Explain The role of serotonin in neural explainations (4)
- One explanation for OCD concerns the role of the neurotransmitter serotonin, which
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. - At least some cases of OCD may be explained by a reduction in the functioning of the serotonin system in the brain.
Decision-making systems (3)
- Some cases of OCD seem to be associated with
impaired decision making. This in turn may be associated with abnormal functioning
of the lateral side of the frontal lobes in the brain. - The frontal lobes are responsible for logical thinking and making decisions.
- There is also evidence to suggest that an area called the left parahippocampal gyrus is associated with processing unpleasant emotions,
functions abnormally in OCD.
There is good supporting evidence from twin studies Genetic explanation (4)
- One strength of the genetic explanations is that there is evidence from a variety of sources for the idea that some people are vulnerable to OCD as a result of their genetic make-up.
- One of the best sources of evidence for the importance of genes is twin studies.
- Nestadt et al. (2010) reviewed previous twin studies and found that 68% of identical twins shared OCD as opposed to 31% of non-identical twins.
- This strongly suggests a genetic influence on OCD.
Limitation of genetic explanations Too many candidate genes (3)
- Although twin studies strongly suggest that OCD is largely under genetic control, psychologists have been much less successful at pinning down all the genes involved.
- One reason for this is because it appears that several genes are involved and that each genetic variation only increases the risk of OCD by a fraction.
- The consequence is that a genetic explanation is unlikely to ever be very useful because it provides little predictive value
There is some supporting evidence
There is evidence to support the role of some neural mechanisms in OCD. For example, some
antidepressants work purely on the serotonin 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.
Also, OCD symptoms form part of a number of other conditions that are biological in origin,
for example Parkinson’s Disease (Nestasdt et al. 2010). This suggests that the biological
processes that cause the symptoms in those conditions may also be responsible for OCD.
It is not clear exactly what neural mechanisms are involved
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 therefore really claim to understand the neural mechanisms involved in OCD.
