The Biological Approach to Explaining OCD
- Genetic Explanation
- Genes are involved in individual vulnerability to OCD.
- Nestadt et al (2010) - 68% of identical twins shared OCD, as opposed to 31% of non-identical twins.
- OCD seems to be polygenic - not caused by one single gene but several genes are involved.
- Taylor (2013) - there are up to 230 genes involvement: possible candicate genes:
- 5HT1-D gene - transport serotonin across synapse.
- SERT gene - regulating serotonin, neurotransmitter > facilitates messages.
- COMT gene - regulates production of dopamine.
- If concordance rate for MZ twins is not 100% this suggest - other factors must be involved for cause of OCD
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The Biological Approach to explaining OCD
- Neural Explanation
- The perception of OCD as a result from abnormality functioning brain mechanism.
- OCD seems to be associated with impaired decision making which in turn may be associated with abnormal functioning of the lateral frontal lobe of the brain.
- Neurotransmitter are responsible for relaying information from one neuron to another.
- If a person has low levels of serotonin then normal transmission of mood-relevant information does not take place - mental process may be affected.
- The left paraphippocampal gyrus - associated with processing unpleasant emotions, functions abnormally in OCD.
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Biological Approach to OCD - Evaluation
- Good supporting evidence
- Nesdath et al - 68% identical twins = OCD. 31% non identical twins =OCD.
- Some people are vulnerable to OCD as a result of their genetic make up.
- It strongly suggest that there is a genetic influence on OCD.
- Too many gene candidate involved
- Several genes are onvolved and that each genetic variation only increases the risk of OCD by a fraction.
- Genetic explanation is unlikely to eve be very useful because it provides little predictive value.
- It isn't completely genetic.
- Environmental factor are involved can trigger or increase the risk of developing OCD.
- Cromer et al (2007) - OCD patients had a traumatic event in the past, OCD was more severe in those with more than one trauma.
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Biological Approach to Treating OCD
- Drug Therapy - aims to increase/decrease levels of neurotransmitter i the brain to increase/decrease their activity.
- Drugs work in various ways to increase the level of serotonin in the brain.
- SSRIs - work on the serotonin system in the brain. Serotonin released by certain neurons in the brain.
- Neurotransmitter chemically conveys the signal from the presynaptic neuron to the postsynaptic neuron - it is reabsorbed by the presynaptic neuron where it is broken down and re-used.
- Prevention of re-absorbtion and breakdown of serotonin SSRIs effectively increase its levels in the synapse.
- Compensates for whatever is wrong with the serotonin system in OCD.
- Takes 3-4 months of daily use of SSRIs to have impact on symptoms.
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Biological Approach to treating OCD
- Combination of SSRIs with CBT
- Drugs reduce patients's emotional symptoms such as anxious or depressed.
- Patients can engage more effectively with the CBT
- Alternative to SSRI = SNRIs
- Serotonin-noradrenaline reuptaake inhibitors.
- Clomipramine - second line of defence for patients who dont's respond to SSRIs.
- SNRIs increase levels of serotonin as well as another different neurotrasmitter - noradrenaline.
- SNRI has also been used to treat OCD in the last 5 years
- Ha the same effect on the serotonin system as SSRIs.
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Biological Approach Treatment to OCD - Evaluation
- Drug therapy tuckles OCD symptoms.
- Clear evidence that SSRIs reduces the severity of OCD symptoms = improving the quality of life for OCD pateitns.
- Soomro et al (2009) - compared SSRIs to placebos in treatment of OCD. = all 17 studies showed significantly better results for SSRIs than Placebos conditions.
- SSRI's combined with a psychological treatment (CBT) is very effective.
- Cost effectve and non-distruptive
- Drug treatments are cheap compared to psychological treatments.
- SSRIs are non-disruptive to patient's lives as it declines sumptoms and does not engage with hard wok of psychological therapy.
- Many doctors and patients prefers drug treatments for these reasons.
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Biological Approach Treatment to OCD - Evaluation
- Drugs can have side effects
- Side effects such as indigestion, blurred vision and loss of sex drive are usually temporary.
- Patients taking Clomipramine have common side effects = becoming aggressive and suffer disruption to blood pressure and heart rhythm.
- One OCD pateitns stop taking medication, it can have factors which reduces effectiveness of the drug therap.
- In some cases, psychological therapies is better than drug therapy.
- Some cases, OCD follow trauma
- OCD is widely believed to be biological in origin - standard of treatment should be biological
- It is acknowledge that OCD can have a range of other causes in some cases, a response to a traumatic life event.
- If OCD is caused by trauma, drug treatment may not be appropriate.
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