Biological approach to explaining OCD

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Why is the COMT gene asociatied with OCD?
Because it is more regularly found in people with OCD
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What does the COMT gene do?
It produces (Catechol-O-transferase) COMT which regulates the neurotransmitter, dopamine
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In what form is the COMT gene most likly to contribute to OCD
in the allel which produices lower activity and allows for higher dopamine which contributes to OCD Tukel (2013)
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How may the SERT gene contrbute to OCD?
by creating low levels of Seretonin
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what evidence has Ozaki eth al (2003) that the SERT gene contributes to OCD?
The same gene mutation was found in 6/7 members of two unrelated families that suffered from OCD
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Which other disorders is the SERT gene a component of?
Depression and PTSD
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What is the exact relation between these genes and OCD?
these genes are the diathasis for a range of psychopathologies including depression and PTSD. Other stressors determine if a mental illness will or can develop
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How did Szechtman et al (1997) conclude that high levels of dopamine are a factor in OCD?
through animal tests Szechtman et al (1997) demonstrated that the body movments of animals with artifically high levels of dopamine are similar to the stereotyped movments of an individual with OCD
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How did Piggott et al (1990) and Jenicke (1992) make the argument that low levels of seretonin contributes to OCD?
Pigott (1990) deomonstrated that antidepressents aimed at increasing the levels of seretonin where effective in curing OCD. inversly Jenicke (1992) demonstrated that anti depressents that do not increase seretonin hve little effect on OCD
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What is the normal function of the claudate nucleus?
The Claudate Nucleus is located in the basil ganglia and supresses signals from the orbitofrontal cortex (OFC).
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What is the normal function of the OFC?
to saind signals to the thalamus about things that are worrying, like germs
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What happens when the caudate nucleus is damaged?
It fails to supress minor worry signals from the OFC which go to the thalamus. The Thalamus sends the signal back to the OFC creatuing a worry circuit
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What evidence is there to support the worry circuit?
PET scans reveal that while OCD symptoms are active (germ phope holdign a dirty cloth) there is heightened activity in the OFC
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Why might abnormal levels of seretonin cause the claudate nuclei to fail?
Comer (1998) provided evidence that seretonin plays a key role in the OFC and the Claudate nuclei
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Why might abnormal levels of dopamine contribute to abnormal brain circuits?
Sukel (2007) showed that because dopamine is the main nerotransmitter in the basil ganglia high levels would cause overactivity
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E1: How did Nestadt et al (2000) use family studies to demonstrate the genetic factor in OCD?
He compared 80 OCD sufferers with 343 of their first degree relatives. He used a control study of 73 people without an mental illnesses compared to 300 of their first degree relatives
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E1: What did Nestadt et al (2000) find?
Nestadt et al (2000) idnetified that first degree relatives of an OCD sufferer were 5 times more likely to suffer from a mental illness themselves
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E1: what did Billet et al (1998) find from reviewing 14 twin studies on OCD?
In MZ twins one is twice as likely to deelop OCD if the other sufers a mental illness compared to DZ twins
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E1: In non of the biological studies was the concordance rates 100%. what should we conclude from that?
That environmental factors still play a significant role. This reinforces the concept of diathasis stress
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E2: how did Pauls and Leckman (1986) conclude that Tourette's syndrome was a different expression of the same gene that contributed to OCD?
Tourette's paitents shared the same obsessional behaviour as OCD sufferers
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E2: which other mental disorders is OCD asociated with?
OCD sufferers share the same compulsive behaviour with autistic children and anorexia sufferers
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E2: how many OCD sufferers also suffer from depression?
2/3
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E2: what does this support?
There is no specific gene that causes OCD but only causes a predisposition
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E3: how did Menzines (2007) show that OCD sufferers have a aquire high amounts of certain neurotransmitters on a genetic basis?
by conducting MRI scans of OCD sufferers and comparing them to healthy individuals Menzies (2007) demosntrate that they had reduced amounts of grey matter in the basil ganglia
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E4: How has biological reaserch into OCD had real world implications?
the ability to identify the mutated COMT gene means that potential mothers can have their eggs screened and abort the ones with the mutated COMT gene thus lowering the chance of OCD in an offspring
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E4: What alternatives to abortion does the mother have, and what are the ethical implications?
Certain genes like the mutated COMT gene can be turned off, however this does raise the question of whether that gene may have certain unseen benefits that would effect the woman health, especially since there isn't a straight forward causal link
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E5: How can learning theory be used to explan OCD?
Dirt is the can become associated with anxiety. the association is maintained through avoidance leading to an obsession being formed such as hand washing
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E5: What is ERP and how does it help tackle OCD?
ERP (exposure and response prevention) works similarly to SD, it encourages the patient to confront the feared stimulus while depriving them of their compulsive behviour
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E5: how successful is ERP?
it helps 60-90% of OCD sufferers
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What does the COMT gene do?

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It produces (Catechol-O-transferase) COMT which regulates the neurotransmitter, dopamine

Card 3

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In what form is the COMT gene most likly to contribute to OCD

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Card 4

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How may the SERT gene contrbute to OCD?

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Card 5

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what evidence has Ozaki eth al (2003) that the SERT gene contributes to OCD?

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