The biological approach to explaining OCD

Question 1

Outline Lewis’ observation and what does his study suggest

Answer 1

• observed that of his OCD patients 37% had parents with OCD and 21% had siblings with OCD, this suggests that OCD runs in families

Question 2

According to the diathesis-stress model…

Answer 2

• certain genes make some people more likely to suffer from a mental disorder, it is not certain however as some environmental stress is necessary to trigger the condition

Question 3

Outline how candidate genes can relate to OCD

Answer 3

• candidate genes can create a vulnerability towards OCD some of these genes are involved in regulating the development of the serotonin systems

Question 4

Give evidence to support the claim that OCD is polygenic

Answer 4

• Taylor analysed findings of previous studies and found evidence that up to 230 different genes may be involved in OCD
• these genes include those associated with the action of dopamine and serotonin, both neurotransmitters are believed in playing a role in regulating mood

Question 5

Define aetiologically heterogeneous

Answer 5

• one group of genes may cause OCD in one person but a different group of genes may cause the disorder in another person meaning the origin of OCD has different causes

Question 6

What is the role serotonin has to play in the development of OCD

Answer 6

• if a person has low levels of serotonin then normal transmissions of mood-relevant info does not take place
• mood and other mental processes are affected

Question 7

OCD in particular hoarding disorder seem to be associated with impaired decision making, how may this relate to the frontal lobes of the brain

Answer 7

• it may be associated with abnormal functioning of the lateral of the frontal lobes

Question 8

What other part of the brain functions in an abnormal way in OCD

Answer 8

• parahippocampal gyrus which is associated with processing unpleasant emotions

Question 9

What is a strength of the genetic explanation (refer to Nestadt et al)

Answer 9

• good supporting evidence
• Nestadt et al 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 in OCD

Question 10

What is a limitation of the genetic explanation (refer to cromer in your answer)

Answer 10

• it seems that environmental factors can trigger or increase the chance of developing OCD
• Cromer et al half the OCD patients had a traumatic event occur in the past and OCD was more severe in those with more than one trauma
• OCD cannot be entirely genetic in origin

Question 11

What is a strength of the neural explanation

Answer 11

• some supporting evidence
• some antidepressants work purely on the serotonin system, causing the levels of serotonin to increase which reduces OCD symptoms, showing that the serotonin system is involved in OCD

Question 12

What is a limitation of the neural explanation

Answer 12

• the abnormal functioning in some areas of the brain could be a result of OCD rather than a cause and so we should not assume that neural mechanisms cause OCD