Explaining OCD

Question 1

How does the biological approach see OCD?

Answer 1

As being similar to physical illnesses caused by abnormal biological processes.​

Question 2

What are the two explanations of the biological approach?

Answer 2

Genetic explanations.

Neural explanations.

Question 3

Outline the genetic explanation of OCD.

(Genetic explanation)

Answer 3

Centres on OCD being inherited through genetic transmission.

Research focuses on twin and family studies to assess whether this is a valid view point.​​

Question 4

What is an issue with testing the genetic explanation of OCD?

(Genetic explanation)

Answer 4

Twin studies - trying to separate relative influences of genes and the environment.

Question 5

Outline Lewis’ study from 1936.

(Supports the genetic explanation of OCD)
(Genetic explanation)

Answer 5

Supports the hereditary explanation of OCD.

This is because they found that of an observational sample: 37% had parents with OCD​ and 21% had siblings with OCD​.

This suggests that OCD runs in families, although what is passed from one generation to the next is genetic vulnerability, not the certainty of OCD.

Question 6

Outline Nestadt et al’s study from 2010.

(Supports the genetic explanation of OCD)
(Genetic explanation)

Answer 6

Supports the genetic explanation of OCD.

This is because they reviewed previous twin studies and found that 68% of monozygotic twins shared OCD as opposed to 31% of dizygotic twins.​

This strongly suggests that there is a genetic influence on OCD.

Question 7

What are gene-mapping studies?

(Genetic explanation)

Answer 7

Studies involving the comparison of genetic material from OCD sufferers and non-sufferers.​

Question 8

Other than allowing the comparison of genetics between OCD sufferers and non-sufferers, what else can gene-mapping be used for?

(Genetic explanation)

Answer 8

See whether OCD truly is separate disorder, as OCD sufferers often also have Tourette’s syndrome.​

Question 9

What do gene-mapping studies suggest about OCD?

(Genetic explanation)

Answer 9

Indicate a genetic link to OCD, with particular genes being involved that make some individuals more vulnerable to developing the disorder than others.

Question 10

Outline Fallon and Nields’ study from 1994.

(Supports the neural explanation of OCD)
(Genetic explanation)

Answer 10

Supports the neural explanation of OCD.

This is because they reported that 40% of people contracting Lyme’s disease incur neural damage resulting in psychiatric conditions including OCD.

This suggests that the neural explanation can account for the onset of some cases of OCD.

Question 11

Outline Grootheest et al’s study from 2005.

(Supports the idea that different types of OCD are formed from individual causes)
(Genetic explanation)

Answer 11

Supports the idea that different types of OCD are formed from individual causes.

This is because they found that OCD originating in childhood is more genetic in nature than that originating in adulthood.

This suggests there may be different types of OCD with different causes.

Question 12

State two general evaluation points of the genetic explanation of OCD.

(Genetic explanation)

Answer 12

The fact that family members often display dissimilar OCD symptoms e.g. a child arranging dolls and an adult constantly washing dishes, weakens support for the genetic viewpoint, as if the disorder was inherited then surely exhibited behaviours would be the same.

Despite the fact that research indicates there are neural differences between OCD sufferers and non-sufferers, it is still not known how these differences relate to the precise mechanisms of OCD.

Question 13

What does COMT (gene) mean?

(The COMT gene)
(Genetic explanation)

Answer 13

It is called the COMT gene because it is involved in the production of catechol-O-methyltransferase. ​

Question 14

What does the COMT gene do?

(The COMT gene)
(Genetic explanation)

Answer 14

Regulates the breakdown of the neurotransmitter dopamine (which has been implicated in OCD).​

Question 15

How is a version of the COMT gene allele involved in OCD?

(The COMT gene)
(Genetic explanation)

Answer 15

All genes come in alleles, and one allele of the COMT gene has been found to be more common in OCD patients than people without the disorder.​

This variation produces lower activity of the COMT gene and higher levels of dopamine.​

Question 16

What does SERT mean?

(The SERT gene)
(Genetic explanation)

Answer 16

SERT -> SERotonin Transporter

Question 17

What is 5-HTT?

(The SERT gene)
(Genetic explanation)

Answer 17

An explanation of OCD, due to differing allele variants of the SERT gene.

This affects the transport of serotonin, creating lower levels of serotonin.; the lower levels are also implicated in OCD.

Question 18

How does the SERT gene affect the body?

(The SERT gene)
(Genetic explanation)

Answer 18

Decreases serotonin.

Question 19

What is serotonin?

(The SERT gene)
(Genetic explanation)

Answer 19

A neurotransmitter involved in mood regulation, sleep, and memory.

Question 20

Outline Ozaki et al’s study from 2003.

(Supports the SERT gene as a genetic explanation of OCD)
(The SERT gene)
(Genetic explanation)

Answer 20

Supports the SERT gene as a genetic explanation of OCD.

This is because they found a mutation of this gene in two unrelated families where six of the seven family members had OCD.

This suggests that the gene may have directly created the onset of OCD.

Question 21

What are the 3 neural explanations of OCD?

(Neural explanation)

Answer 21

Role of NTs.

Role of brain structures.

Infections.

Question 22

Outline infections in OCD.

(Infections)
(Neural explanation)

Answer 22

Some forms of OCD have been linked to breakdowns in the immune system functioning, such as through contracting throat infections, Lyme’s disease, and influenza.

This indicates a biological explanation through damage to neural mechanisms. ​

Question 23

What did Pichichero state in 2009?

(Infections)
(Neural explanation)

Answer 23

That damage to neural mechanisms through infections, that goes on to form OCD is more often seen in children than adults.​

Question 24

What have PET scans shown about OCD?

(PET Scans and the Orbital Frontal Cortex)

Answer 24

That OCD sufferers can have relatively highly levels of activity in the OFC.

Question 25

What role does the OFC play in OCD? (PET Scans and the Orbital Frontal Cortex)

Answer 25

Help initiate activity upon receiving impulses to act and then stop the activity when the impulse lessens.​ A non-sufferers may have an impulse to wash dirt from their hands; once this is done the impulse to perform the activity stops, and thus so does the behaviour.​ It may be that those with OCD have difficulty in switching off or ignoring impulses, so they turn into obsessions, resulting in compulsive behaviour.

Question 26

What are PET scans? (PET Scans and the Orbital Frontal Cortex)

Answer 26

A type of medical imaging, using a medical radioactive isotope within the bloodstream across blood-brain barrier.

Question 27

What is the OFC? (PET Scans and the Orbital Frontal Cortex)

Answer 27

A brain area associated with higher-level thought processes and conversion of sensory information into thoughts.​

Question 28

Where in the brain is thought to be involved in OCD? (Abnormal brain circuits) (Neural explanation)

Answer 28

Several areas in the frontal lobe of the brain.

Question 29

How does the worry cycle work for a non-sufferer? (Abnormal brain circuits) (Neural explanation)

Answer 29

The caudate nucleus (located in the basal ganglia) normally suppresses signals from the OFC. In turn, the OFC sends a signal to the thalamus about the things that are worrying, e.g. a potential germ hazard.​ When the caudate nucleus is damaged, it fails to suppress minor ‘worry’ signals and the thalamus is alerted, which in turn sends signals back to the OFC, as a worry circuit.​

Question 30

How does the worry cycle work for a non-sufferer? (Abnormal brain circuits) (Neural explanation)

Answer 30

The caudate nucleus suppresses the OFC's signals. The OFC then signals to the thalamus to stop worrying.

Question 31

How does the worry cycle work for a sufferer? (Abnormal brain circuits) (Neural explanation)

Answer 31

A damaged caudate nucleus fails to suppress the OFC's signals. This alerts the thalamus, sending signals back to the OFC, and as the caudate nucleus is damaged it cannot suppress the OFC signals so alerts the thalamus again, continuously.

Question 32

Are dopamine levels thought to be high or low in OCD?

Answer 32

Abnormally high in OCD.

Question 33

Outline Pigott et al's study from 1990. (Challenges the idea that dopamine is involved in OCD) (Abnormal levels of neurotransmitters) (Neural explanation)

Answer 33

Challenges the idea that dopamine is involved in OCD. This is because they believed that lower levels of serotonin are associated with OCD. This conclusion is based on the fact that anti-depressant drugs that increase serotonin activity have been found to reduce OCD symptoms. This suggests that serotonin may be of greater importance in explaining OCD onset.

Question 34

What is the basal ganglia?

Answer 34

A group of structures linked to the thalamus in the base of the brain and involved in co-ordination and movement.

Question 35

What is the caudate nucleus?

Answer 35

Located centrally and near basal ganglia vital role in how the brain learns, specifically storing and processing of memories. It works as a feedback processor which means that it uses information from past experiences to influence future actions and decisions.

Question 36

What is the thalamus?

Answer 36

Located deep within the brain and involved in sensory and motor single relay and the regulation of consciousness and sleep.

Question 37

What is aetiologically heterogeneous?

Answer 37

The idea that a number of different combinations of genes can lead an illness. E.g. OCD.