Biological approach to explaining OCD

Question 1

What are concordance rates?

Answer 1

The measure of genetic similaritiy.

Question 2

Explain Lewis et al’s study into the concordance rate between OCD and their family.

Answer 2

• 37% had parents with OCD.
• 21% had siblings with OCD.
• Suggests OCD runs in families.

Question 3

What are candidate genes?

Answer 3

They have been identified as creating vulnerability for OCD.

Question 4

What are polygenic genes?

Answer 4

OCD is not caused by one particular gene, but instead a combination of genetic variations increasing vulnerability.

Question 5

What is the COMT gene responsible for?

Answer 5

breaking down neurotransmitters (such as dopamine) and brings you’re your heartbeat down to a normal levels and helps you manage stress.

Question 6

What is the SERT gene?

Answer 6

Linked to the neurotransmitter serotonin and affects the transport of the serotonin, causing lower levels of serotonin which is also associated with OCD (and depression)

Question 7

What does aetiologically heterogeneous mean?

Answer 7

One group of genes may cause OCD in one person but a different group may result In OCD in another.

Question 8

Explain the role of serotonin as a neural explanation?

Answer 8

• Neurotransmitters send messages from one neuron to
  another.
• Low levels of serotonin affect the transmission of mood
  relevant information.
• A person then experiences low mood, as well as other
  mental processes.
• At least some cases may be explained by a reduction in
  the functioning of the serotonin system in the brain.

Question 9

What is a strength of genetic explanations? - Research support

Answer 9

• Evidence for OCD being a part of their genetic make-up.
• Nestadt reviewed twin studies: 68% of MZ twins shared OCD. 31% non-identical twins shared OCD.
• People with a family member with OCD are 4x more likely to develop it.

Question 10

What is a limitation of the genetic explanation? - Fail to consider environmental risk factors

Answer 10

• Some people are more likely to be vulnerable than others.
• Cromer et al found that over half of OCD patients had experienced a traumatic event.

Question 11

What is a strength of the neural model? - Research support

Answer 11

• Antidepressents that work on serotonin have been provided to reduce OCD, showing serotonin plays a role.
• OCD symptoms have been shown to form part of Parkinson’s - biological disorder.
• If a biological disorder produces OCD symptoms, we assume the biological processes causes OCD.

Question 12

What is a limitation of the neural model? - The serotonin-OCD link isn’t unique to OCD

Answer 12

• Many people with OCD experience clinical depression (2 disorders is called co-morbidity).
• Depression likely involves disruption to the action of serotonin.
• If serotonin is disrupted with OCD, as well as with depression, then serotonin may not be relevant to OCD symptoms.