List two behavioural characteristics of OCD
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Nestadt 2010
68% monozygotic twins both diagnosed with OCD and 31% dizygotic twins
Whilst this provides evidence that genes play a role, it also indicates that they cannot be the only factor as monozygotic twins share 100% of their DNA, hence if this was the only factor the concordance rate would be 100%; this does however support the diathesis stress model as it could be that an environmental factor is required also.
Why is the usefulness of the genetic explanation limited?There are potentially thousands of candidate genes due to OCD being aetiologically heterogenous, ergo finding a definitive cause and ergo cure is unlikelyDescribe serotonin as a neural explanation of OCDLow levels of serotonin leads to impaired transmission of mood related information, leading to a lowered mood and linked to the obsessive thoughts characterising OCDWhat area of the brain functioning abnormally leads to impaired decision making and OCD symptoms?Abnormal functioning of the frontal lobeWhat area of the brain functioning abnormally leads to greater processing of negative emotions?Abnormal functioning of the parahippocampal gyrusWhat is the supporting evidence for the role of serotonin as a cause of OCD?Antidepressant studies - increased levels of serotonin reduce OCD symptoms, suggesting it's related to its onset and developmentWhy is the idea of OCD's comorbidity with depression a limiting factor?As depression is also linked to low levels of serotonin, meaning the OCD-serotonin link is not unique and that the low levels of serotonin seen in patients may be due to accompanying depression and not OCDWhy is the cause-effect relationship between serotonin and OCD not known?It is unclear whether low levels of serotonin cause OCD or whether it's the other way around, weakening the neural explanation.What is the purpose of drug therapies to treat OCD?To increase the levels of a specific neurotransmitter (serotonin, noradrenaline) in the brain, which in turn increases the stimulation of the post synaptic neuron.What does SSRI stand for?selective serotonin reuptake inhibitorDescribe the action of SSRI's-as serotonin is released by the presynaptic neuron, it travel across a synapse as it chemically conveys the mood related information/ action potential to the post synaptic neuron, where it is then reabsorbed by the presynaptic neuron to be reused or broken down -SSRI's prevent the reabsorption and breakdown of serotonin, increasing its levels in the synapse and causing it to continue stimulating the postsynaptic neuron to compensate for its low levels.What is the benefit of using SSRI's in combination with CBT?There is a decrease in emotional symptoms which allows the individual to engage more actively with the CBTWhat is the dosage of Fluoxetine (SSRI)?20mg per day, can be increased gradually. Around 3-4 months to see major improvementName the older antidepressant that has more side effects than SSRI's and give an exampleTricyclics e.g. clomipramineWhat are SNRI's and when are they used?Serotonin-noradrenaline reputable inhibitor Same action as SSRI's but with both serotonin and noradrenaline Used in those who do not respond to SSRI'sGive evidence of the effectiveness of SSRI'sSoomro et al 2009 found SSRI's saw better results than the control placebo group, proving their effectivenessLimitation of the effectiveness of SRRIs as a treatment for OCDSkapinakis et al. 2016 - argued cognitive and behavioural therapies work better than antidepressants for OCDWhy is the non-disruptive and cost effective nature of drug therapies a benefit?1. Doesn't interfere with the life of the patient - saves them time. 2. Costs less than psychological treatments therefore it is good value for public health systemsWhy can't we trust the evidence of the effectiveness of SSRIs?Effectiveness of SSRI's is biased because drug companies suppress evidence (don't publish) that doesn't support their effectivenessAs with any medication, what is a major limitation of antidepressants?Side effects, e.g. indigestion, loss of sex drive, blurred vision.