The biological approach to explaining OCD

Question 1

What are the 2 types of OCD explanation?

Answer 1

Neural and genetic

Question 2

What 2 genes may contribute to OCD?

Answer 2

The COMT gene and the SERT gene

Question 3

What does the COMT gene do?

Answer 3

Regulates the production of a neurotransmitter called dopamine

Question 4

What is a neurotransmitter?

Answer 4

A chemical substance that transmits nerve impulses across a synapse

Question 5

What is dopamine?

Answer 5

A neurotransmitter involved with motivation and ‘drive’

Question 6

How is the COMT gene linked to OCD?

Answer 6

One allele of the gene is more common in OCD patients than people without the disorder

Question 7

How does the OCD variation of the COMT gene lead to OCD symptoms?

Answer 7

It produces lower activity of the COMT gene and higher levels of dopamine

Question 8

What does the SERT gene do?

Answer 8

Affects the transportation of serotonin

Question 9

What does SERT do to serotonin levels?

Answer 9

Decreases them

Question 10

What did a study regarding the SERT gene find?

Answer 10

In two unrelated families who had a mutated SERT gene, 6 of the 7 family members had OCD

Question 11

In OCD patients, what are dopamine levels expected to be?

Answer 11

Higher than normal

Question 12

What did animal studies find about dopamine?

Answer 12

High doses of drugs that enhance dopamine levels induce stereotyped movements resembling the compulsions of OCD patients

Question 13

What is the name of the brain circuit associated with OCD?

Answer 13

The worry circuit

Question 14

What are the 3 brain structures involved in the worry circuit?

Answer 14

The caudate nucleus, the OFC and the thalamus

Question 15

What does the caudate nucleus do in an individual without OCD?

Answer 15

Supresses signals from the orbitofrontal cortex

Question 16

What does the caudate nucleus do in an individual with OCD?

Answer 16

Fails to supress minor ‘worry’ signals

Question 17

What does the orbitofrontal cortex do?

Answer 17

Sends signals to the thalamus about things that are worrying

Question 18

What support is there for the worry circuit?

Answer 18

PET scans taken while OCD symptoms were active found heightened activity in the OFC

Question 19

Which neurotransmitters are involved in the worry circuit?

Answer 19

Dopamine and serotonin

Question 20

What are the 4 AO3 points of the biological explanation of OCD?

Answer 20

1) Family + twin studies
2) Alternative explanations
3) Research support for genes and OFC
4) Tourette’s syndrome

Question 21

In the first degree relative study into OCD, how many OCD participants were there?

Answer 21

80

Question 22

In the first degree relative study into OCD, how many relatives of OCD participants were there?

Answer 22

343

Question 23

In the first degree relative study into OCD, how many non-OCD participants were there?

Answer 23

73

Question 24

In the first degree relative study into OCD, how many relatives of the non-OCD participants were there?

Answer 24

300

Question 25

In the first degree relative study into OCD, what was found about the people who had a first-degree relative with OCD?

Answer 25

They were 5x more likely to develop OCD at some point in their life

Question 26

What did a twin study meta analysis find about OCD?

Answer 26

MZ twins were twice as likely to develop OCD if their co-twin had it, compared to DZ twins

Question 27

What type of explanation challenges the biological explanation of OCD?

Answer 27

Psychological explanations

Question 28

Which psychological model can be applied to the explanation of OCD?

Answer 28

Mowrer's two process model

Question 29

How can the two process model be applied to OCD?

Answer 29

A neutral stimulus is associated with anxiety - the association is maintained as the anxiety-inducing stimulus is avoided - this leads to the development of an obsession

Question 30

How can the diathesis stress model be applied to OCD?

Answer 30

OCD manifests in genetically vulnerable individuals after an activating event that triggers the responsible genes

Question 31

In the study that supports the role of genes + the OFC, who was in the experimental group?

Answer 31

People with OCD and their immediate family members who didn't have OCD

Question 32

In the study that supports the role of genes + the OFC, who was in the control group?

Answer 32

Individuals without OCD who were unrelated to the experimental group

Question 33

In the study that supports the role of genes + the OFC, what were the findings?

Answer 33

The OCD patients and their relatives had reduced grey matter in key regions of the brain, including the OFC

Question 34

What did researchers find about Tourette's syndrome in relation to OCD?

Answer 34

That OCD is one form of expression of the same gene that determines Tourette’s

Question 35

For which other disorders are the obsessions observed in OCD and Tourette’s patients also observed? (2)

Answer 35

Anorexia nervosa and autism