The Biological Explanation of OCD

Question 1

How does the biological approach see OCD?

Answer 1

Being similar to physical illnesses caused by abnormal biological processes.

Question 2

What are the 2 main biological explanations for OCD?

Answer 2

Genetic and Neural explanations

Question 3

What is the genetic explanation?

Answer 3

Hereditary influences through genetic transmission from parent to offspring.

Question 4

What is the neural explanation?

Answer 4

Abnormal functioning of neural mechanisms and neurotransmitters.

Question 5

What are the main two genes involved in the genetic explanation?

Answer 5

COMT and SERT gene

Question 6

Why is the gene called the COMT gene?

Answer 6

It is involved in the production of catechol-O-methyltransferase

Question 7

What does the COMT gene do?

Answer 7

Regulates the production of the neurotransmitter dopamine.

Question 8

Why is the COMPT gene linked to OCD?

Answer 8

As it regulates dopamine which is implicated to OCD.

Question 9

One form/allele of the COMT gene is more common in what?

Answer 9

OCD patients than people without the disorder.

Question 10

One form/allele of the COMT gene produces what?

Answer 10

Produces lower activity of the COMT gene and higher levels of dopamine

Question 11

What is another name for the SERT gene?

Answer 11

5-HTT

Question 12

What does the SERT gene do?

Answer 12

Affects the transport of serotonin creating lower levels of the neurotransmitter

Question 13

What are low levels of serotonin associated with?

Answer 13

OCD

Question 14

Ozaki et al. Found out what about the SERT gene?

Answer 14

A mutation of the gene in 2 unrelated families where 6/7 had OCD

Question 15

What is the hormone involved in the neural explanation?

Answer 15

Serotonin

Question 16

What does serotonin do?

Answer 16

Regulates mood

Question 17

Lower levels of serotonin are associated with what?

Answer 17

Mood disorders

Question 18

What is further support for the role of serotonin in OCD?

Answer 18

It comes from research examining anti-depressants

Question 19

What has been found about drugs that increase serotonin levels?

Answer 19

They are effective in treating OCD

Question 20

Higher levels of dopamine as associated with what?

Answer 20

Symptoms of OCD particularly the compulsive behaviour.

Question 21

What are the two regions in the brain that have been implicated with OCD?

Answer 21

Basal ganglia and orbitofrontal cortex

Question 22

What does the orbitofrontal cortex (OFC) do?

Answer 22

Converts sensory information into thoughts and impulses including ‘worry signals’

Question 23

What have PET scans found about the orbitofrontal cortex (OFC)?

Answer 23

Higher activity in patients with OCD

Question 24

A suggestion is that the heightened activity in the orbitofrontal cortex increases what?

Answer 24

The conversion of sensory information and worry signals to actions resulting in compulsions

Question 25

What is the basal ganglia?

Answer 25

A brain structure involved in multiple processes such as the coordination movements.

Question 26

What is the name of the nucleus located in the basal ganglia?

Answer 26

Caudate nucleus

Question 27

What does the caudate nucleus do?

Answer 27

Suppress signals from the OFC

Question 28

What is the link between the caudate nucleus and OCD?

Answer 28

Those with OCD have a difficulty in switching off or ignoring signals actions sent from the OFC as the caudate nucleus is damaged

Question 29

What happens if the caudate nucleus is damaged?

Answer 29

Prevents patients from stopping compulsive behaviours.

Question 30

The link between the caudate nucleus is supported by what?

Answer 30

PET scans of patients with OCD taken while their symptoms are active. Scans show heightened activity in the OFC.

Question 31

What did Comer et al report about serotonin?

Answer 31

It plays a key role in the operation of the OFC and the caudate nuclei.

Question 32

What did Comer et al report about abnormal levels of serotonin?

Answer 32

Cause the areas of the OFC and caudate nuclei to malfunction.

Question 33

What does high levels of dopamine do to the basal ganglia where it is located?

Answer 33

Over activity

Question 34

A strength of the genetic explanation is that there is evidence that people are vulnerable to OCD because of their genetic makeup. What evidence supports this?

Answer 34

A review of twin studies found that 68% of identical twins shared OCD compared to 31% of non-identical twins.

Question 35

A strength of the genetic explanation is that there is evidence that people are vulnerable to OCD because of their genetic makeup. How can this be evaluated?

Answer 35

There is supporting evidence for genetic influence on OCD. Validity of the theory increases. Make effective treatment to alter levels of serotonin and dopamine.

Question 36

A weakness of the genetic explanation is that twin studies assume that identical twins are only more similar than non-identical twins in terms of their genes. What evidence supports this?

Answer 36

They overlook that identical twins may also be more similar in terms of shared environment as non-identical may be boy and girl who have different experiences.

Question 37

A weakness of the genetic explanation is that twin studies assume that identical twins are only more similar than non-identical twins in terms of their genes. How can this be evaluated?

Answer 37

Limits the validity of using evidence from twin studies. It is not clear if findings are due to genetics or similar environment . Impossible to determine genes as a causal factor in OCD.

Question 38

A strength of the neural explanation what Max et al. found. What evidence is there to support this?

Answer 38

When the basal ganglia is disconnected from the frontal cortex during surgery, OCD-like symptoms are reduced.

Question 39

A strength of the neural explanation what Max et al. found. How can this be evaluated?

Answer 39

Support for the role of the basal ganglia and OCD. Supports the validity Implications for possible treatment for OCD focused on activating the basal ganglia.

Question 40

A weakness of the neural explanation is that environmental factors can also trigger or increase the risk of developing OCD. What evidence supports this?

Answer 40

It has been found that over half of OCD patients in one study had a traumatic experience in their past, and that OCD was more severe with more trauma.

Question 41

A weakness of the neural explanation is that environmental factors can also trigger or increase the risk of developing OCD. How can this be evaluated?

Answer 41

The biological explanation is reductionist. Environmental factors play a part and OCD may be nature and nurture. According to diathesis-stress model biological factors may be predisposition rather than a cause.