Biological explanations of OCD

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  • Created by: asusre
  • Created on: 18-04-21 16:24
What is obsessive compulsive disorder?
Obsessive Compulsive Disorder is a condition characterised by obsessions, which are recurring thoughts or images and/or compulsions, which are repetitive behaviours such as hand-washing.
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What are the behavioural characteristics of OCD?
Compulsions are repetitive.
Compulsive behaviours are used to reduce the anxiety created by obsessions.
Avoidance of situations that might trigger anxiety.
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What are the emotional characteristics of OCD?
Obsessive thoughts can be distressing, creating anxiety.
OCD is often accompanied by depression.
The sufferer can feel irrational guilt or disgust.
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What are the cognitive characteristics of OCD?
Obsessions - recurring intrusive thoughts that are perceived as inappropriate or forbidden.
Awareness that obsessions and compulsions are irrational.
Hypervigilance - overly aware of obsession, constant alertness of potential hazards.
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Which study found concordance rates between MZ and DZ twins for OCD?
Nestadt et al (2010) found that 68% of identical twins shared OCD as opposed to 31% of non-identical twins.
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What is the diathesis-stress model?
The diathesis-stress model suggests that some people have a genetic predisposition to OCD, but symptoms only present themselves following a trigger from the environment.
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What are candidate genes?
Candidate genes are specific genes which may cause OCD.
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What candidate gene for OCD involves serotonin?
SERT genes, also called 5-HTT, affect the transportation of serotonin. A mutation of SERT genes may be involved with OCD.
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What does it mean to say that OCD is polygenic?
Polygenic means that OCD is likely to be caused by several different genes.
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What study found that OCD is polygenic?
Taylor (2013) found that up to 230 different genes may be involved in OCD.
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What candidate gene for OCD involves dopamine?
The COMT gene regulates the production of dopamine. One form of the COMT gene has been found to be more common in OCD patients than people without the disorder.
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What does it mean that OCD is aetiologically heterogenous?
Aetiologically heterogenous means that the causes/origins (aetiology) of OCD varies from person to person (heterogenous), so different genes may cause different types of OCD for different people.
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What is one strength of the genetic explanation of OCD?
The genetic explanation of OCD has research support.
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What study supports the genetic explanation of OCD?
Nestadt et al (2010) found that 68% of identical twins shared OCD as opposed to 31% of non-identical twins.
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What is a problem of using concordance rates to prove the genetic explanation of OCD?
Concordance rates are not 100% for MZ twins, so genes are not the only factor causing OCD.
Monozygotic twins share more similar environments which may impact the concordance rate, rather than genetics.
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What is one limitation of the genetic explanation of OCD?
One limitation of the genetic explanation of OCD is that there are also environmental risk factors.
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What study investigated the effect of trauma on OCD?
Cromer et al. (2007) found that over half the OCD patients in their sample had a traumatic event in their past and OCD was more severe in those with more than one trauma.
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What is a neurochemical imbalance?
A neurochemical imbalance refers to abnormal levels of neurotransmitters in the brain, which may cause OCD.
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What is the role of serotonin in causing OCD?
Serotonin helps regulate mood. Lower levels of serotonin have been found in OCD sufferers which suggests that reduced serotonin levels in the brain may cause OCD.
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What is the role of dopamine in causing OCD?
Dopamine has effects on motivation. Abnormally high levels of dopamine have been found in people with OCD which suggests that elevated levels of dopamine in the brain may cause OCD.
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How could abnormal brain circuits cause OCD?
Abnormalities in the orbitofrontal-subcortical pathway is linked to OCD.
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Explain how abnormalities in the orbitofrontal-subcortical pathway is linked to OCD.
The orbitofrontal cortex sends signals about worrying things in the environment to the caudate nucleus in the basal ganglia, which suppresses signals from the orbitofrontal cortex, and if it fails to, they are sent back to the orbitofrontal cortex, acting
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How does an overactive orbitofrontal cortex cause excessive worrying?
The orbitofrontal cortex is overactive in people with OCD, which could explain compulsions. Excessive activity in this loop has been suggested to result in obsessive thoughts becoming ‘trapped’.
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What are the strengths of the neural explanation of OCD?
The neural explanation has reserach support and SSRIs are effective for treating OCD.
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What study supports the neural explanation of OCD?
Fineberg et al. (2017) used fMRI scanners to compare activity in the brain between people with OCD and controls and found that OCD sufferers had greater activity in their frontal cortex when anticipating an electric shock compared to a control group.
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What study supports the effectiveness of SSRIs?
Soomro et al (2009) found that 70% of patients with OCD find SSRIs effective in reducing their symptoms.
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What is a limitation of the neural explanation of OCD?
The neural explanation of OCD is biologically reductionist as it does not consider the effect of environmental and cognitive factors.
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Card 2

Front

What are the behavioural characteristics of OCD?

Back

Compulsions are repetitive.
Compulsive behaviours are used to reduce the anxiety created by obsessions.
Avoidance of situations that might trigger anxiety.

Card 3

Front

What are the emotional characteristics of OCD?

Back

Preview of the front of card 3

Card 4

Front

What are the cognitive characteristics of OCD?

Back

Preview of the front of card 4

Card 5

Front

Which study found concordance rates between MZ and DZ twins for OCD?

Back

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