the biological approach to explaining OCD

Question 1

genetic explanations - basis

Answer 1

• OCD is a condition that may be largely understood as biological in nature
• genes are involved in individual vulnerability in OCD
• Aubrey Lewis observed that 37% of his OCD patients had parents with OCD, 21% had siblings with OCD
• suggests that OCD runs in families, although what is likely passed is genetic vulnerability, not the certainty of OCD
• the diathesis-stress model says that certain genes leave some people more likely to develop a mental disorder, but it is not certain
• some environmental stress is necessary to trigger the condition

Question 2

genetic explanations - candidate genes

Answer 2

• researchers have identified genes which create vulnerability for OCD
• some of these are involved in regulating the development of serotonin

Question 3

genetic explanations - OCD is polygenic

Answer 3

• OCD is not caused by one single gene but by a combination of genetic variations that together increase vulnerability
• Steven Taylor found that up to 230 genes are involved in OCD

Question 4

genetic explanations - different types of OCD

Answer 4

• one group of genes may cause OCD in one person but a different group of genes may cause it in another (aetiologically heterogeneous)
• some evidence to suggest that different types of OCD may be the result of particular genetic variations

Question 5

neural explanations - the role of serotonin

Answer 5

• neurotransmitters relay info from one neuron to another
• if someone has low levels of serotonin then transmission of mood-relevant info does not take place and the person may experience low mood

Question 6

neural explanations - decision making systems

Answer 6

• some cases of OCD are associated with impaired decision-making
• abnormal functioning of the lateral of the frontal lobes of the brain, frontal lobes responsible for logical thinking and making decisions
• evidence to suggest that the parahippocampal gyrus functions normally with OCD, this usually processes unpleasant emotions

Question 7

evaluation of genetic explanations - research support

Answer 7

• evidence from a variety of sources which strongly suggests some people are vulnerable to OCD due to their genetic makeup
• Gerald Nestadt reviewed twin studies, found 68% of identical twins shared OCD, compared to 31% of non-identical

Question 8

evaluation of genetic explanations - environmental risk factors

Answer 8

• OCD does not appear to be completely genetic in origin, environmental risk factors can also trigger or increase the risk of developing OCD
• Kiara Cromer found that over half of her OCD clients had experienced a traumatic event in the past
• OCD was more severe in those with multiple traumas

Question 9

evaluation of neural explanations - research support

Answer 9

• antidepressants that work on serotonin are effective in reducing OCD symptoms, suggesting the involvement of serotonin
• OCD symptoms form part of conditions that are known to be biological, such as Parkinson’s

Question 10

evaluation of neural explanations - no unique neural system

Answer 10

• serotonin-OCD link may not be unique to just OCD
• many people with OCD also experience clinical depression, this is called co-morbidity
• depression probably involves disruption to the action of serotonin
• could be that serotonin is only abnormal in people with OCD because they have depression too