Biological approach: Explaining OCD Flashcards
Genetic explanations
Biological approach: Explaining OCD - Genetic explanations
Genes are involved in individual vulnerability to OCD
Lewis observed that of his OCD patients, 37% had parents w/ OCD & 21% had siblings w/ OCD
Suggests OCD runs in families, although genetic vulnerability is passed from one gen to the next
Diathesis-stress model suggests certain genes leave some people more likely to develop a mental disorder
Some environmental stress is necessary to trigger the condition
Candidate genes
Biological approach: Explaining OCD - Genetic explanations
Researchers have identifief genes, which create vulnerability for OCD, called candidate genes
Some of these genes are involved in regulating the development of serotonin system
E.g. gene 5HT1-D beta is implicated in transport of serotonin across synapses
OCD is polygenic
Biological approach: Explaining OCD - Genetic explanations
OCD is not caused by a single gene but by a combo of genetic variations that together sigly increase vulnerability
Taylor has analysed findings of previous studies & found evidence that up to 230 diff genes may be involved in OCD
Genes that have been studied in relation to OCD include those associated w/ action of DA as well as serotonin, both neurotransmitters believed to have a role in regualting mood
Different types of OCD
Biological approach: Explaining OCD - Genetic explanations
One group of genes may cause OCD in one person but a diff group of genes may cause disorder in another person
OCD is aetiologically heterogenous
There is also evidence to suggest that diff types of OCD may be result of particular genetic variations
Evaluation: Research support
Biological approach: Explaining OCD - Genetic explanations
Strength: strong evidence base
There is evidence from variety of sources which strongly suggests some people are vulnerale to OCD as result of genetic-make up
Nestadt et al reviewed twin studies and found that 68% of MZ twins shared OCD as opposed to 31% of DZ twins
Marini & Stebnicki found that a person w/ a family member diagnosed w/ OCD is 4x more likely to develop it than someone w/o
Therefore, these studies suggest that there must be some genetic influence on development of OCD
Evaluation: Environmental risk factors
Biological approach: Explaining OCD - Genetic explanations
Limit: there are also environmental risk factors
Strong evidence for idea that genetic variation can make a person more or less vulnerable to OCD
However, OCD doesn’t trigger or increase risk of developing OCD
Cromer et al found half the OCD clients in their sample has experienced a traumatic event in their past
OCD was also more severe in those w/ 1 or more traumas
Therefore, genetic vulnerability only provides a partial explanation for OCD
Role of serotonin
Biological approach: Explaining OCD - Neural explanations
Neurotransmitters are responsible for relaying info from 1 neuron to another
If person has low levels of serotonin then normal transmission of mood-relevent info doesn’t take place & person may experience low moods
At least some cases of OCD may be explained by reduction in functioning of serotonin system in brain
Decision-making systems
Biological approach: Explaining OCD - Neural explanations
Some cases of OCD, seem to be associated w/ impaired decision-making
This in turn may be associated w/ abnormal functioning of lateral of frontal lobes
Frontal lobes are responsible for logical thinking & making decisions
Also evidence to suggest the lefr parahippocampal gyrus associated w/ processing unpleasant emotions, functions abnormally in OCD
Evaluation: Research support
Biological approach: Explaining OCD - Neural explanations
Strength: existence of supporting evidence
Antidepps that work purely on serotonin are effective in reducing OCD symptoms & this suggests serotonin may be involved in OCD
Also, OCD symptoms form part of conditions that are known to be biological in origin, such as Parkinson’s disease, which causes muscle tremors & paralysis (Nestadt et al)
If biological disorder produces OCD symptoms, we may assume bio processes underlie OCD
Therefore, bio factors may be responsible for OCD
Evaluation: No unique neural system
Biological approach: Explaining OCD - Neural explanations
Limit: Serotonin-OCD link may not be unique to OCD
Many people w/ OCD experience clinical depp - this is co-morbidity
Depp probably involves disruption to action if serotonin
This leaves logical problem when it comes to serotonin as possible basis for OCD
Could simply be that serotonin activity is disrupted in many people w/ OCD because they are depped as well
Therefore, serotonin may not be relevant to OCD symptoms
