4.5: Genetic explanations

Question 1

Biological approach

Answer 1

The biological approach is the perception of OCD as determined by physiological means with treatments based upon chemical means

Question 2

What is the biological approach also known as?

Answer 2

The biological approach is also known as the medical model

Question 3

The biological approach is also known as the medical model and sees abnormal conditions as being similar to physical illnesses caused by what?

Answer 3

The biological approach:

1. Is also known as the medical model
2. Sees abnormal conditions as being similar to physical illnesses caused by abnormal biological processes

Question 4

The biological approach is also known as the medical model and sees abnormal conditions as being similar to physical illnesses caused by abnormal biological processes.
What are 2 possible biological explanations?

Answer 4

2 possible biological explanations are:

1. Hereditary influences through genetic transmission
2. The occurrence of OCD through damage to neural (brain) mechanisms

Question 5

Genetic explanation

Answer 5

The genetic explanation is the perception of OCD as transmitted through inherited factors

Question 6

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, what is the problem with twin studies?

Answer 6

As in other areas of psychology, the problem with twin studies is separating out the relative influences of:

1. Genes
2. Environment

Question 7

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of what, more recent attention has been upon gene-mapping studies?

Answer 7

With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies

Question 8

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies.
What do gene-mapping studies involve?

Answer 8

Gene-mapping studies involve comparing genetic material from:

1. OCD sufferers
2. Non-sufferers

Question 9

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies.
Gene-mapping studies involve comparing genetic material from OCD sufferers and non-sufferers.
Why do such studies also permit researchers to see whether OCD truly is a separate disorder?

Answer 9

Such studies also permit researchers to see whether OCD truly is a separate disorder, because OCD sufferers often also have Tourette’s syndrome

Question 10

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies.
Gene-mapping studies involve comparing genetic material from OCD sufferers and non-sufferers.
Such studies also permit researchers to see whether OCD truly is a separate disorder, because OCD sufferers often also have Tourette’s syndrome.
What do results from both forms of study indicate?

Answer 10

Results from both forms of study indicate a genetic link to OCD

Question 11

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies.
Gene-mapping studies involve comparing genetic material from OCD sufferers and non-sufferers.
Such studies also permit researchers to see whether OCD truly is a separate disorder, because OCD sufferers often also have Tourette’s syndrome.
Results from both forms of study indicate a genetic link to OCD, with particular genes being involved that make some individuals what?

Answer 11

Results from both forms of study indicate a genetic link to OCD, with particular genes being involved that make some individuals more vulnerable to developing the disorder than others

Question 12

The genetic explanation centres on OCD being inherited through genetic transmission, with research originally centring on twin and family studies to assess whether this viewpoint is valid and, if so, to what extent genes do play a part.
However, as in other areas of psychology, the problem with twin studies is separating out the relative influences of genes and environment.
With the introduction of DNA profiling, more recent attention has been upon gene-mapping studies.
Gene-mapping studies involve comparing genetic material from OCD sufferers and non-sufferers.
Such studies also permit researchers to see whether OCD truly is a separate disorder, because OCD sufferers often also have Tourette’s syndrome.
Results from both forms of study indicate a genetic link to OCD, with particular genes being involved that make some individuals more vulnerable to developing the disorder than others.
What is unlikely?

Answer 12

It is unlikely that single genes cause OCD

Question 13

It is unlikely that single genes cause OCD.

What is more likely?

Answer 13

It is more likely that it is a combination of genes that determine an individual’s level of vulnerability to the condition

Question 14

It is unlikely that single genes cause OCD.
It is more likely that it is a combination of genes that determine an individual’s level of vulnerability to the condition.
Although there seems to be some genetic similarity between OCD and Tourette’s syndrome, what is current thinking?

Answer 14

Although there seems to be some genetic similarity between OCD and Tourette’s syndrome, current thinking is that they are 2 separate disorders

Question 15

The genetic explanation sees OCD is being inherited.

What predict its presence?

Answer 15

Gene markers predict its presence

Question 16

Some mental disorders appear to have a stronger what than others, and OCD is a good example of condition that may be largely understood as biological in nature?

Answer 16

Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of condition that may be largely understood as biological in nature

Question 17

Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of condition that may be largely understood as biological in nature.
One form of biological explanation is the genetic explanation.
Genes are involved in individual vulnerability to OCD.
What did Lewis (1936) observe?

Answer 17

Lewis (1936) observed that of his OCD patients:

1. 37% had parents with OCD
2. 21% had siblings with OCD

Question 18

Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of condition that may be largely understood as biological in nature.
One form of biological explanation is the genetic explanation.
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.
What does this suggest?

Answer 18

This suggests that OCD runs in families

Question 19

Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of condition that may be largely understood as biological in nature.
One form of biological explanation is the genetic explanation.
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 what, not what?

Answer 19

This suggests that OCD runs in families, although what is probably passed on from one generation to the next is:
1. Genetic vulnerability
,not
2. The certainty of OCD

Question 20

Some mental disorders appear to have a stronger biological component than others, and OCD is a good example of condition that may be largely understood as biological in nature.
One form of biological explanation is the genetic explanation.
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 model, what?

Answer 20

According to the diathesis-stress model:
1. Certain genes leave some people more likely to suffer a mental disorder
,but
2. It is not certain - some environmental stress (experience) is necessary to trigger the condition

Question 21

Researchers have identified genes that create vulnerability for OCD, called what?

Answer 21

Researchers have identified genes that create vulnerability for OCD, called candidate genes

Question 22

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
What are some of these genes involved in doing?

Answer 22

Some of these genes are involved in regulating the development of the serotonin system

Question 23

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
Example

Answer 23

For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses

Question 24

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses.
However, like many conditions, what does OCD seem to be?

Answer 24

Like many conditions, OCD seems to be polygenetic

Question 25

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses.
However, like many conditions, OCD seems to be polygenetic.
What does this mean?

Answer 25

This means that OCD is:
1. Not caused by one single gene
,but that
2. Several genes are involved

Question 26

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses.
However, like many conditions, OCD seems to be polygenetic.
This means that OCD is not caused by one single gene, but that several genes are involved.
What has Taylor (2013) done?

Answer 26

Taylor (2013) has:

1. Analysed the findings of previous studies
2. Found evidence that up to 230 different genes may be involved in OCD

Question 27

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses.
However, like many conditions, OCD seems to be polygenetic.
This means that OCD is not caused by one single gene, but that several genes are involved.
Taylor (2013) has analysed the findings of previous studies and found evidence that up to 230 different genes may be involved in OCD.
What do genes that have been studied in relation to OCD include?

Answer 27

Genes that have been studied in relation to OCD include those associated with the action of:
1. Dopamine
,as well as
2. Serotonin

Question 28

Researchers have identified genes that create vulnerability for OCD, called candidate genes.
Some of these genes are involved in regulating the development of the serotonin system.
For example, the gene 5HT-D beta is implicated in the efficiency of transport of serotonin across synapses.
However, like many conditions, OCD seems to be polygenetic.
This means that OCD is not caused by one single gene, but that several genes are involved.
Taylor (2013) has analysed the 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 doing what?

Answer 28

Genes that have been studied in relation to OCD include those associated with the action of:
1. Dopamine
,as well as
2. Serotonin
, both neurotransmitters believed to have a role in regulating mood

Question 29

One group of genes may cause OCD in one person, but what?

Answer 29

One group of genes may cause OCD in one person, but a different group of genes may cause OCD in another person

Question 30

One group of genes may cause OCD in one person, but a different group of genes may cause OCD in another person.
What is the term used to describe this?

Answer 30

The term used to describe this is aetiologically heterogeneous

Question 31

One group of genes may cause OCD in one person, but a different group of genes may cause OCD in another person.
The term used to describe this is aetiologically heterogeneous.
What does this mean?

Answer 31

This means that the origin (aetiology) of OCD has different causes (heterogeneous)

Question 32

One group of genes may cause OCD in one person, but a different group of genes may cause OCD in another person.
The term used to describe this is aetiologically heterogeneous.
This means that the origin (aetiology) of OCD has different causes (heterogeneous).
What is there also some evidence to suggest?

Answer 32

There is also some evidence to suggest that different types of OCD may be the result of particular genetic variations

Question 33

One group of genes may cause OCD in one person, but a different group of genes may cause OCD in another person.
The term used to describe this is aetiologically heterogeneous.
This means 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, for example what?

Answer 33

There is also some evidence to suggest that different types of OCD may be the result of particular genetic variations, for example:

1. Hoarding disorder
2. Religious obsession

Question 34

What are the 2 genetic explanations?

Answer 34

The 2 genetic explanations are:

1. Individual genes
2. Family structure

Question 35

The 2 genetic explanations are individual genes and family structure.
1. Individual genes:
What seem to be present with OCD?

Answer 35

1. Gene 9
2. COMT
3. SERT
   seem to be present with OCD

Question 36

The 2 genetic explanations are individual genes and family structure.
1. Individual genes:
Gene 9, COMT and SERT seem to be present with OCD.
However, there may be as many as 230 separate genes that may be involved in what?

Answer 36

There may be as many as 230 separate genes that may be involved in the development of OCD

Question 37

The 2 genetic explanations are individual genes and family structure.
1. Individual genes:
Gene 9, COMT and SERT seem to be present with OCD.
However, there may be as many as 230 separate genes that may be involved in the development of OCD - meaning what?

Answer 37

There may be as many as 230 separate genes that may be involved in the development of OCD - meaning that the disorder is polygenetic

Question 38

The 2 genetic explanations are individual genes and family structure.
2. Family structure:
In the general population, 2% have OCD.
However, among first degree relatives, what is the figure?

Answer 38

Among first degree relatives, the figure is 10%

Question 39

The 2 genetic explanations are individual genes and family structure.
2. Family structure:
In the general population, 2% have OCD.
However, among first degree relatives, the figure is 10%, indicating what?

Answer 39

Among first degree relatives, the figure is 10%, indicating a genetic basis

Question 40

The 2 genetic explanations are individual genes and family structure.
2. Family structure:
In the general population, 2% have OCD.
However, among first degree relatives, the figure is 10%, indicating a genetic basis.
Twin studies also provide evidence with concordance rates among MZ twins as high as what?

Answer 40

Twin studies also provide evidence with concordance rates among MZ twins as high as 87%

Question 41

The 2 genetic explanations are individual genes and family structure.
2. Family structure:
In the general population, 2% have OCD.
However, among first degree relatives, the figure is 10%, indicating a genetic basis.
Twin studies also provide evidence with concordance rates among MZ twins as high as 87%, compared to what % with DZ twins?

Answer 41

Twin studies also provide evidence with concordance rates among:
1. MZ twins as high as 87%
,compared to
2. 47% with DZ twins

Question 42

Genetic explanation research:
Lenane et al. (1990) performed a study into the prevalence of OCD among related family members, finding evidence for the existence of heritable contributions to the onset of the disorder.
This supports the genetic viewpoint.

Samuels et al. (2007) used gene mapping to compare OCD sufferers who exhibited compulsive hoarding behaviour with those who didn’t, finding a link to a chromosome, implying a genetic influence to compulsive hoarding behaviour, which may also indicate the existence of a separate OCD sub-type.

Stewart et al. (2007) performed gene mapping on OCD patients and family members, finding that a variant of the OLIG-2 gene commonly occurred, which suggests a genetic link to the condition.

Tang et al. (2014) decided that as complex genetics hinder attempts to understand their role in OCD in humans, they would perform research using dogs.
Dogs suffer from naturally occurring compulsive disorders that closely model human OCD, but the limited diversity within dog breeds makes identifying genetic influences easier.
Gene analysis showed that OCD-affected dogs had significantly higher levels of particular gene variants than dogs without the condition, which suggest a genetic link to OCD.
The extent to which the findings can be generalised to humans, however, is debatable.

Answer 42

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Question 43

Genetic explanation evaluation:
For:
1. As evidence indicates genetic factors are at work in the expression of some forms of OCD, especially obsessions about contamination, aggression and religion, and compulsions involving washing, ordering and arranging, it may well be that some types of OCD are more genetic in nature than others.

2. As studies like Grootheest et al. (2005) OCD originating in childhood is more genetic in nature than that originating in adulthood.
   This suggests that there may be different types of OCD with different causes.
3. There is good supporting evidence.
   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.

Against:
1. Although research suggests a genetic component to OCD, there must be some environmental influences upon the disorder, or else the concordance rate between MZ twins would be 100%.

2. There does not appear to be a single gene involved in the transmission of OCD.
   Instead, what research suggests is that many genes are scattered throughout the genome that each contribute a small amount to an individual’s overall risk of developing the disorder.
   Whether an individual does go on to develop the disorder is then dependent on the degree of environmental triggers that an individual encounters.
3. Pato et al. (2001) report that a substantial amount of evidence suggests that OCD is a heritable condition, but that few details are understood about actual genetic mechanisms underpinning the disorder.
   This indicates the need for more focused research.
4. The fact that family members often display dissimilar OCD symptoms, for example a child arranging dolls and an adult constantly washing dishes, weakens support for the genetic viewpoint, because if the disorder was inherited then surely exhibited behaviours would be the same?
5. Too many candidate genes.
   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.
6. Environmental risk factors.
   It seems that environmental factors can also trigger or increase the risk of developing OCD (the diathesis-stress model).
   For example, 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.
7. Twin studies are flawed as genetic evidence.
   Twin studies are a standard source of evidence for genetic influence.
   However, 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 more similar in terms of shared environments.
   For example, non-identical twins might be a boy and a girl who have quite different experiences.
8. While evidence from family studies seem to indicate a strong genetic factor, these studies cannot fully control for the influence of shared environmental factors (such as diet) and social learning theory in their methods.
   Conversations abut and awareness of OCD will be more common with a sufferer in the household, making other family members more likely to seek treatment.

Answer 43

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