Genetic Approach to OCD

Question 1

What are Genetic Explanations?

Answer 1

These are hereditary influences transmitted from parent to offspring by genetic transmission.

Question 2

What are candidate genes?

Answer 2

Genes that create vulnerability to OCD

Question 3

What does polygenetic mean?

Answer 3

OCD is not caused by one single gene but by a combination of genetic variations that together cause significantly increased vulnerability

Question 4

What did Taylor (2013) find?

Answer 4

Taylor (2013) found evidence from previous studies that there are up to 230 different genes which may be involved with OCD

Question 5

What did Tukel et al. (2013) find?

Answer 5

Tukel et al. (2013) suggested a variation of the COMT gene may contribute to OCD as it is more common in patients who suffer from OCD than in those that do not. This variation produces higher levels of dopamine and lower activity of the COMT gene

Question 6

What is the 5-HTT gene?

Answer 6

The 5-HTT gene has also been linked with OCD as it affects the levels of serotonin, making them less and these lower levels of the neurotransmitter are linked with OCD

Question 7

Genetic explaination strengths:

Answer 7

A strong evidence base of research, especially within twin studies.

Nestadt et al. (2010) reviewed evidence that 68% of identical twins will both have OCD compared to 31% of non-identical twins. Marini et al (2012) found a person with a family member diagnosed with OCD is around 4 times as likely to develop it as someone without

This is a significant link to show that genetics play an important role in the development of OCD and that nature (in the nature/nurture debate) is shown to play a large role here.

Grootheest et al. (2005) found their genetic link was stronger in children that were sufferers of OCD.

Question 8

Genetic explaination limitations:

Answer 8

Ignores environmental factors, although twin studies are used as there is a greater genetic link, these twins also share the same environment, which could trigger OCD.

There is evidence to suggest that identical twins are treated ‘more similar’ in terms of their environment, (e.g. expectations, style of dress, extracurricular activities) than non-identical twins who are treated more as individuals.

Pato et al. (2001) noted that although there does seem to be a genetic link between OCD sufferers, there is not enough understanding about the actual genetic mechanisms causing OCD.

Grootheest et al. (2005) found that the genetic link was stronger in children that were sufferers of OCD, than when the OCD originated in adulthood, showing the probability of different causes.

Question 9

List neural explainations:

Answer 9

Serotonin is known to play a role in regulating mood, if a person has low levels of serotonin, the person can have low moods and other mental processes are often affected. The reduction of serotonin can explain some cases of OCD

Dopamine levels are thought to be abnormally high in people who suffer from OCD

Question 10

Abnormal brain circuits:

Answer 10

The orbital Frontal Cortex (OFC), sends signals to the thalamus about things that are worrying you, this area of the brain is overactive in people who suffer from OCD
The thalamus, which is the part of the brain that instructs the person to do a certain activity or behaviour, in OCD sufferers, this would be the ODC behaviour
The caudate nucleus is the part of the brain that in non-OCD suffers, surprises the messages from the OFC, and normalises the worry, however, in OCD suffers, this part of the brain is not completing this job and allows the OFC to make the sufferer worry. This could be due to damage or overstimulation