9. Biological Approach To Explaining OCD

Question 1

What is a genetic explanation?

Answer 1

Genes passed down by parents are the cause of OCD

Question 2

Who did Lewis observe in 1936?

Answer 2

OCD patients and their family members

Question 3

What percentage of Lewis’ patients had parents with OCD?

Answer 3

37%

Question 4

What percentage of Lewis’ patients had siblings with OCD?

Answer 4

21%

Question 5

What is likely passed down through the genes rather than genetic certainty?

Answer 5

Genetic vulnerability

Question 6

What does the diathesis-stress model say?

Answer 6

Certain genes leave people more likely to suffer a mental disorder, but it is not certain

Question 7

What are candidate genes?

Answer 7

Genes that create vulnerability for OCD

Question 8

What are some OCD candidate genes involved in?

Answer 8

Regulation of the serotonin system

Question 9

What gene is thought to affect the transport of serotonin across synapses?

Answer 9

5HT1-D beta

Question 10

What does polygenic mean?

Answer 10

Many genes influence a trait

Question 11

How many genes did Taylor find in 2013 could be linked to OCD?

Answer 11

230

Question 12

What two neurotransmitters are most believed to be associated with OCD?

Answer 12

Serotonin, dopamine

Question 13

What does aetiologically heterogenous mean?

Answer 13

The genes that cause OCD are different from person to person

Question 14

What types of OCD are most likely the result of particular genetic variations?

Answer 14

Hoarding disorder, religious obsession

Question 15

What did Nestadt et al study in 2010?

Answer 15

Twin studies relating to OCD

Question 16

In Nestadt et Al’s study, what percentage of identical twins shared OCD?

Answer 16

68%

Question 17

In Nestadt et Al’s study, what percentage of non-identical twins shared OCD?

Answer 17

31%

Question 18

What did Cromer et al find in 2007 about the past of OCD patients?

Answer 18

Over half had a traumatic event in their past, and OCD was more severe in those who had more than one trauma

Question 19

What are neurotransmitters responsible for?

Answer 19

Relaying information between neurons

Question 20

What are neural explanations?

Answer 20

OCD is determined by the behaviour of the nervous system, including the brain and neurotransmitters

Question 21

What happens if someone has low levels of serotonin?

Answer 21

Their mood is affected

Question 22

What neurotransmitter abnormality can sometimes explain OCD?

Answer 22

Serotonin

Question 23

What do some cases of OCD, in particular hoarding disorder, seem to be associated with?

Answer 23

Impaired decision making

Question 24

What part of the brain can impaired decision making be associated with?

Answer 24

The lateral frontal lobes

Question 25

What are the lateral frontal lobes responsible for?

Answer 25

Logical thinking and decision making

Question 26

What other part of the brain functions abnormally in OCD?

Answer 26

Parahippocampal gyrus

Question 27

What is the parahippocampal gyrus associated with?

Answer 27

Processing unpleasant emotions

Question 28

What drug treatment can be given to reduce symptoms of OCD?

Answer 28

Antidepressants

Question 29

Why does the effectiveness of antidepressants show that OCD can be related to the serotonin system?

Answer 29

Antidepressants work purely on the serotonin system

Question 30

What is the issue with using brain systems to identify OCD?

Answer 30

No system has been found that always plays a role in OCD

Question 31

Why should we not argue neurotransmitter or brain structure abnormalities cause OCD?

Answer 31

They may be the result, rather than the cause

Question 32

What other mental disorder do people with OCD usually face?

Answer 32

Depression

Question 33

What is co-morbidity?

Answer 33

Having two mental disorders together

Question 34

Why is accompanying depression an issue for explaining OCD?

Answer 34

The disruption to the serotonin system may be from depression, rather than OCD

Question 35

Why are twin studies flawed as genetic evidence?

Answer 35

As well as having shared genes identical twins are likely to have a more similar environment than non-identical twins

Question 36

Why might non-identical twins not have the same environment?

Answer 36

They could be opposite genders, which leads to different life experiences

Question 37

What are the 3 aspects of the genetic explanation of OCD

Answer 37

- candidate genes - OCD is polygenic - there are different types of OCD

Question 38

What is an example of a candidate gene for OCD

Answer 38

5HT1-D, which is implicated in the efficiency of transport of serotonin across synapses

Question 39

Two weaknesses of genetic explanation

Answer 39

- too many candidate genes | - environmental risk factors

Question 40

Too many candidate genes

Answer 40

- psychologists have been largely unsuccessful at pining down all of the genes involved in OCD - this is largely because there are several genes involved, and each genetic variation increases risk by only a fraction - so the genetic explanation is unlikely to ever be very useful because it provides very little predictive value

Question 41

environmental risk factors

Answer 41

- environmental factors can also trigger OCD (diathesis risk model) - so OCD can not be entirely genetic in origin, at least not in all cases - it may be more productive to focus on the environmental causes because we are more able to do something about these

Question 42

An example of environmental stress causing OCD

Answer 42

- Cromer eat al Found that over half of the OCD patients in their sample had a traumatic event in their lives, and the OCD was more severe in those with more than one trauma

Question 43

Neural explanations

Answer 43

The view that physical and psychological characteristics are determined by the behaviour of the nervous system, in particular the brain as well as individual neurons.

Question 44

Role of serotonin

Answer 44

a neurotransmitter believed to help regulate mood

Question 45

A strength of neural explanations of OCD

Answer 45

- supporting evidence - some antidepressants which work purely on the serotonin system by increasing levels, have effectively reduced OCD symptoms - OCD symptoms also form part of other biological originated conditions like Parkinson's disease, suggesting biological processes that cause symptoms in those conditions may also be responsible for OCD

Question 46

3 weaknesses of the biological approach to explaining OCD

Answer 46

- it is not clear exactly what neural mechanisms are involved - we should not assume that the neural mechanisms cause OCD - the serotonin ocd link may simply be co morbidity with depression

Question 47

It is not clear exactly what neural mechanisms are involved

Answer 47

- cavedini et als study has shown that these neural systems are the same systems that function abnormally in OCD - but, research has also identified other brain systems that may be involved sometimes, but no system has been found that always plays a role in OCD So we can't really claim to understand the neural mechanisms involved in OCD

Question 48

We should not assume the neural mechanisms cause OCD

Answer 48

There is evidence suggesting that various neurotransmitters and brain structures function abnormally in OCD patients, but we can't be sure that these cause it- they could develop because of it

Question 49

The serotonin-ocd link may simply be co morbidity with depression

Answer 49

- many ocd sufferers also become depressed (co-morbidity) - this depression likely involves disruption to the serotonin system - so we can't be sure that serotonin disruption is involved with OCD: it may be that the serotonin system is simply disrupted because the patient is depressed as well