The biological approach to explaining OCD

A Level Psychology Psychopathology (The biological approach to explaining OCD): Biological approach definition

A perspective that emphasises the importance of physical processes in the body such as genetic inheritance and neural function.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Genetic explanations definition

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 transmitted from parents to offspring.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Neural explanations definition

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.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of a condition that may be largely understood as biological in nature.

One form of biological explanation is the genetic explanation.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Genes are involved in individual vulnerability to OCD

Lewis (1936) observed that of his OCD patients 37% had parents with OCD and 21% had siblings with OCD.

This 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.

According to the diathesis-stress mode 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.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Researchers have identified genes, which create vulnerability for OCD, called candidate genes.

Some of these genes are involved in regulating the development of the serotonin across synapses.

A Level Psychology Psychopathology (The biological approach to explaining OCD): 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 aswell as serotonin, both neurotransmitters believed to have a role in regulating mood.

A Level Psychology Psychopathology (The biological approach to explaining 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 of OCD has different causes.

There is some evidence to suggest that different types of OCD may be the result of particular genetic variations, such as hoarding disorder and religious obsession.

A Level Psychology Psychopathology (The biological approach to explaining OCD): One explanation for OCD concerns the role of the neurotransmitters serotonin which is believed to help regulate mood.

Neurotransmitters are responsible for relating information to help regulate mood.

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.

A Level Psychology Psychopathology (The biological approach to explaining OCD): Some cases of OCD and in particular hoarding disorder, seem to be associated with impaired decision making.

This in turn may be associated with abnormal functioning of the lateral of the frontal lobes of the brain. The frontal lobes are the front part of the brain that are responsible for logical thinking and making decisions.

There is also evidence to suggest an area called the left parahippocampal gyrus associated with processing unpleasant emotions, functions abnormally in OCD.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): 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.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): 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 consequences is that a genetic explanation is unlikely to ever be very useful because it provides little predictive value.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): It seems that environmental factors can also trigger or increase the risk of developing OCD

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.

This suggests that 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 more able to do something about these.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): There is evidence to support the role of some neural mechanisms in OCD

Some antidepressants work purely on the serotonin, increasing levels of this neurotransmitter.

Such drugs are effective in reducing OCD symptoms and this suggests that the serotonin system is involved in OCD.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): OCD symptoms form part of a number of other conditions that are biological in origin, for example Parkinson's disease.

This suggests that the biological processes that cause the symptoms in those conditions may also be responsible for OCD.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): Studies of decision making have shown that these neural systems are the same systems that function abnormally in OCD.

Research has also identified other brain systems that may be involved sometimes but no systems has been found that always plays a role in OCD.

We cannot therefore really claim to understand the neural mechanisms involved in OCD.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): There is evidence to suggest that various neurotransmitters and structures of the brain do not function normally in patients with OCD.

This is not the same as saying that abnormal functioning causes the OCD.

These biological abnormalities could be a result of OCD rather than its cause.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): Many people who suffer OCD become depressed, having two disorders together is called co-morbidity.

This depression probably involves disruption to the serotonin system.

This leaves us with a logical problem when it comes to the serotonin system as a possible basis for OCD.

It could simply be that the serotonin system is disrupted in many patents with OCD because they are depressed as well.

A Level Psychology Psychopathology (The biological approach to explaining OCD) (Evaluation): Twin studies are a standard source of evidence for genetic influence.

However, they make the assumption that identical twins in terms of their genes, but overlook the fact that identical twins may also be more similar in terms of shared environments.