The Biological Approach To Explaining Obsessive Compulsive Disorder Flashcards
Genetic explanations for OCD
- Family Studies 👨👩👧👦 👵🏼👴🏼
* Candidate Genes
What does Family Studies show in terms of the genetic explanation of OCD?
The genetic explanation suggests that OCD is inherited through genetic transmission.
Family studies have shown that relatives of OCD sufferers have a greater tendency to suffer from OCD and anxiety related problems themselves.
The disorder seems to be transmitted through families, which indicates a possible genetic contribution to OCD.
Pauls et al 2005 found that 10% of people with 1st degree relative with OCD also suffered from the disorder compared to 2% of people in the general population.
What do Candidate genes show in terms of the genetic explanation of OCD?
Candidate genes are specific genes that have been identified that create a vulnerability for OCD.
1 possible gene is the SERT gene (aka 5-HTT) which affects the transport of serotonin, creating lower levels of this neurotransmitter.
What are the evaluation points of the genetic explanation for OCD?
1) Research Support
2) Environmental influences
3) OCD is polygenic
4) Further research needed
Outline the evaluation point
1) Research Support in terms of genetic explanation for OCD
Point:
Supporting evidence for the genetic bases of OCD comes from studies of 1st degree relatives.
Example:
Nestadt et al 2000 found lifetime incidence of OCD was higher in relatives of OCD patients (11.7%) compared to relatives of healthy Controls (2.7%).
Elaborate:
Additionally, Wendland 2007 found support for the role of specific gene which affects the transportation of serotonin, resulting in little serotonin available for the important cell communication.
Re-cap:
Research strongly suggests generic influence in OCD.
Outline the evaluation point
2) Environmental Influences in terms of genetic explanation for OCD
Point:
Limitation is that concordance rates are never 100%.
Explain:
Means that Environmental factors must play a vital role in the development of OCD.
Example:
Cromer et al 2007 found that over 1/2 of the OCD patients sample had a traumatic experience in their past, and that OCD was more severe in those with more than one trauma.
Elaborate:
Suggests that OCD cannot entirely be genetic in origin and environmental stressors influence its development.
Re-cap:
All evidence suggests that OCD is a complex interaction of nature and nurture and it may be be beneficial to use the diathesis stress model to explain origins of OCD.
Outline the evaluation point
3) OCD is polygenic in terms of genetic explanation for OCD
Point:
OCD is polygenic
Explain:
It’s unlikely that a single candidate gene is responsible for causing OCD; it’s more likely that it’s a combination of genes that determine an individual’s level of vulnerability to the condition.
Elaborate:
Psychologists have been unsuccessful at identifying all the genes involved and there is lack of consistency in research findings regarding specific genes related to OCD.
Example:
1 reason for this is because it appears that several genes are involved and that each genetic variation only increases risk of OCD by a fraction.
Re-cap:
Consequence is that a genetic explanation is unlikely to ever be useful because it provides little predictive value.
Outline the evaluation point
4) Further research needed in terms of genetic explanation for OCD
Point:
Pato 2001 suggests that Further research is needed to investigate the idea that OCD is a heritable condition, as few details are fully understood about the actual genetic mechanisms underpinning the disorder.
Explain:
It may be that different genetic factors, contribute to the different subtypes if OCD e.g. hoarding, tic-related, early-onset.
Example:
Hemmings et al. found that a defect in a gene for dopamine was much less common in people with early onset than late onset of OCD.
Re-cap:
This indicates the need for more focused research to fully understand the role of genes in exposing OCD.
Neural explanations for OCD
- Abnormal levels of neurotransmitters
* Abnormal brain circuits
What is meant by Abnormal Levels Of Neurotransmitters
Lower levels of serotonin are associated with OCD.
Although, serotonin’s contribution to OCD is not fully understood , it’s thought that serotonin has a role in preventing the repetition of tasks.
Lack of serotonin therefore results in loss of a mechanism that inhibits takes repetition.
Antidepressant drugs that increase serotonin activity have been shown to reduce OCD symptoms (Piggot et al 1990) whereas antidepressants that have less effect on serotonin do not reduce OCD symptoms.
Also dopamine levels are thought to be abnormally high in people with OCD.
What is meant by Abnormal brain circuits
Several areas in frontal lobes of brain are thought to be abnormal in people with OCD.
The Caudate Nucleus which is located in the Basal Ganglia normally suppresses signals from the OrbitoFrontal Cortex (OFC).
The OFC sends ‘worry’ signals to the thalamus, such as potential germ hazard.
When the caudate nucleus is damaged it fails to suppress minor worry signals from the OFC and the thalamus is alerted and confirms the worry to the OFC creating a worry circuit.
Serotonin is linked to these regions of the Frontal Cortex. Comer 1998 reports that serotonin plays key role in the operation of the OFC and the caudate nuclei and it appears that abnormal levels in serotonin might cause these areas to malfunction.
What are the evaluation points of NEURAL explanations of OCD
1) Research Support for the neural explanation of OCD.
2) Mixed Support for the role if serotonin in OCD
3) Cause and Effect
4) Alternative Explanations
Outline the evaluation point
1) Research Support for the neural explanation of OCD.
Point:
There’s strong evidence that suggests certain brain circuits are associated with OCD.
Explain:
PET scans of patients with OCD, taken while their symptoms are active (e.g. when person with germ obsession hold dirty cloth) showed heightened activity in the OFC.
Example:
Paul et al 2014 used neuroimaging and repeatedly found unusually high activation within the OFC and several studies have found excessive activity in the Caudate Nucleus for patients with OCD.
Elaborate:
In addition, Hu 2006 compared serotonin activity in 169 OCD sufferers and 253 non - OCD sufferers, finding serotonin levels to be lower in the OCD patients, which supports the idea of low levels of serotonin being associated with the disorder.
Re-cap:
Combined this evidence offers strong support for a NEURALl explanation for OCD.
Outline the evaluation point
2) Mixed Support for the role of serotonin in OCD
Point:
Whilst SSRI’s (selective serotonin reuptake inhibitors) which increase the amount of serotonin in the brain can successfully treat the symptoms of OCD, the exact role of the neurotransmitter in OCD is far from clear.
Explain:
1 problem is serotonin based drugs are not helpful for all sufferers.
Example:
Bastani et al 1990 found that increasing the levels of serotonin in the brain can actually make OCD symptoms worse. Other neurotransmitters have also been implicated in OCD such as dopamine and glutamate.
Elaborate:
It is not clear whether OCD is caused by problems with particular neurotransmitters or by imbalances in how several interact. Symptoms can vary between sufferers so it may even be that OCD has a variety of neurochemical causes.
Re-cap:
Therefore it is unlikely that abnormal levels of serotonin are a sole cause of OCD.
Outline the evaluation point
3) cause and effect
Point:
Limitation of the neural explanations for explaining OCD is that we cannot assume that NEURAL mechanisms cause OCD.
Explain:
Brain scan studies show an association between increased activity in certain brain areas (the OFC, caudate nucleus, serotonin) and OCD.
Elaborate:
As it is only an association it doesn’t show that those brain areas play a role in causing OCD.
Re-cap:
These biological abnormalities could be a consequence of OCD rather than its cause.
