biological explanations of OCD

Question 1

Orbitofrontal cortex

Answer 1

Obsessive focus on negative/ repetitive thoughts - part of brain involved in cognitive processing of decision making

Question 2

Basal Ganglia

Answer 2

Increased activity may be source of compulsions as this part of brain initiates motor functions

Question 3

Candidate genes

Answer 3

Genes that may be involved in producing symptoms of OCD eg 5HT1-D beta

Question 4

Poly genetic

Answer 4

There are different combinations of up to 230 genetic variations - Taylor

Question 5

Aetiologically heterogeneous

Answer 5

Causes are different for different individuals

Question 6

Concordance rates - studies

Answer 6

Nestalt - 68% MZ - 31% DZ
4 times more likely to develop OCD if family member diagnosed - 37% parents - 21% siblings

Question 7

Diathesis-stress model

Answer 7

Genetic vulnerability (diathesis) triggered by an environmental stressor such as trauma

Question 8

biological - Research support

Answer 8

• Strength - strong evidence base
• Variety of sources - some people are vulnerable to OCD
• Twin studies - 68% and 31%
• Family studies - 4 times as likely to develop as someone without
• Suggest that there must be some genetic influence on the development of OCD

Question 9

biological - Environmental risk factors

Answer 9

• Limitation - environmental risk factors
• Genetic variation can make a person more or less vulnerable
• OCD is not entirely genetic - environmental risk factors can also trigger or increase the risk of developing OCD
• Cromer et al - over half of OCD clients in sample had experienced a traumatic event in their past
• OCD more severe in those with one or more traumas
• Genetic vulnerability only provides a partial explanation for OCD

Question 10

biological - Animal studies

Answer 10

• Difficult to find candidate genes
• Evidence from animal studies - particular genes associated with repetitive behaviours in other species eg mice - Ahmari
• However - although mice and humans share most genes, the human mind and brain are much more complex and it may not be possible to generalise from animal repetitive behaviour to human OCD

Question 11

The role of serotonin

Answer 11

Affects mood regulation - low levels = low moods

Question 12

Orbitofrontal cortex - lateral frontal lobes

Answer 12

Increased activity = obsessive focus on negative/repetitive thoughts as part of brain involved in the cognitive processing of decision-making

Question 13

Parahippocampal gyrus

Answer 13

Associated with processing unpleasant emotions, functions abnormally in OCD

Question 14

Basal Ganglia

Answer 14

Increased activity = possible source of compulsions as part of brain that initiates motor functions

Question 15

neural - research support

Answer 15

• Strength of neural model of OCD - existence of some supporting evidence
• Antidepressants - work purely on serotonin are effective in reducing OCD symptoms
• Serotonin may be involved in OCD
• OCD symptoms form part of conditions are known to be biological in origin, such as the degenerative brain disorder - Parkinson’s disease, causes muscle tremors and paralysis - Nestadt et al 2010
• If biological disorder produces OCD symptoms - assume the biological processes underlie OCD
• Biological factors may also be responsible for OCD

Question 16

neural - no unique neural system

Answer 16

• Limitation - serotonin-OCD link may not be unique to OCD
• Many experience clinical depression - co-morbidity
• This depression probably involves disruption to the action of serotonin - logical problem with it comes to serotonin as a possible basis for OCD
• Could simply be that serotonin activity is disrupted in many people with OCD because they are depressed as well
• Serotonin may not be relevant to OCD symptoms

Question 17

neural - correlation and causality

Answer 17

• Evidence to show that some neural systems do not work normally
• This is mostly explained by brain dysfunction causing the OCD
• Simply a correlation between neural abnormality and OCD - does not equal causation
• It is quite possible that OCD causes the abnormal brain function or both are influenced by a third factor