OCD Flashcards

Question

7. Biological explanation of OCD Neural explanations: 2 strengths of the neural explaination of OCD

Answer 1

OFC has empirical supportive evidence from structal and functional imaging studies • empirical evidence from the effects of SSRI's that neurotransmitters do play a role P: OFC has empirical supportive evidence from structal and functional imaging studies Eg: Menzies et al. found that OCD sufferers and their family members had reduced grey matter in the key regions of the brain including the OFC. In addition, several neuroimaging studies using PET scanners have shown hyperactivity in the OFC and the caudate nucleus in people with OCD both while scanning the brain at rest and when symptoms are stimulated Ex: This supports the involvement of the ventral motivation cortico-striato-thalamic circuit in OCD, also known as the 'Worry circuit' Cou: However, one problem with this evidence is that it is correlational: researchers cannot be sure if the hyperactivity in these areas is the cause of OCD or a consequence of having OCD. Maia et al. (2008) reviewed evidence from other lines which permitted stronger causal inferences, including the development of OCD following brain injury, pediatric autoimmune neuropsychiatric disorders associated with streptococcal infection, and neurosurgical lesions that attenuate OCD. L: findings therefore suggest that there are multiple lines of evidence which support the involvement of the OFC and caudate in OCD, which strengthens the involvement of the OFC and caudate in OCD, which strengthens the validity of the biological explanation P: empirical evidence from the effects of SSRI's that neurotransmitters do play a role Eg: A meta-analysis by Soomro et al. (2008) demonstrated SSRIs are more effective than placebos, suggesting there is serotonergic involvement in OCD Ex: These drugs are effective at reducing OCD symptoms, and SSRIs work by increasing the levels of this neurotransmitter by blocking the serotonin reuptake process, the data therefore suggests that serotonin does play a role in OCD. Cou: However despite altering levels of serotonin in the synapse within hours, these drugs take weeks to reduce symptoms, and 40% to 60% of patients show no or just partial symptom improvement L: findings suggest low levels of serotonin have a role to play in OCD but are not the sole cause of OCD

Answer 2

Selective serotonin reuptake inhibitors Common Brand names include: prozac (flouxitine) and sertraline

Answer 3

Low levels of serotonin neurotransmitters SSRI increase levels of serotonin in the brain to regulate mood and anxiety Remember: high levels of serotonin transporter = low levels of serotonin bc the transporter is removing serotonin from the synapse

Answer 4

Neurotransmitters are stored in pre-synaptic vesicles -when an action potential stimulates it, the vesicle is pushed to the end of the axon terminal and fuses with the presynaptic neurons membrane to release the neurotransmitters stored inside it across the synapse from the pre-synaptic neuron to the post-synaptic neuron -the neurotransmitter bind to the post-synaptic receptors which increase or decrease the likelihood of the post-synaptic neuron firing (excites it over the threshold charge so more likely and inhibits lower than the threshold charge so less likely) -the neurotransmitter is cleared from the synapse by reuptake mechanisms -serotonin is a neurotransmitter -OCD is thought to involve a lack of serotonin at the synapse -SSRI's block the reuptake of serotonin, so increase its presence at the synapse -this reduces symptoms of OCD as the serotonin transporter is removing less serotonin from the synapse so there's an increase in serotonin levels SSRI's interfere with step between 3 and 4: -when serotonin is released into the synapse (step 3), it either binds to the postsynatic receptors (step 4) or it's removed from the synapse by reuptake mechanisms - SSRI'S block this reuptake, so more serotonin is present in the synapse so it can bind to post-synaptic receptors

Answer 5

Tricyclic antidepressants -SNRI's (serotonin and noradrenaline reuptake inhibitors) -benzodiazepines

Answer 6

serotonin and noradrenaline reuptake inhibitors Venlafaxime and duloxetine

Answer 7

SNRI's (more selective than tricyclics) block the transporter mechanism that re-absorbs serotonin and noradrenaline -there's a lot of evidence supporting the idea that noradrenaline is involved in OCD. In low levels: person is unable to focus their attention which can result in anxiety and compulsions -although low noradrenaline may not cause OCD, preventing reuptake of this neurotransmitter (increasing it) has been assossiated to relief symptoms and anxiety

Answer 8

-2nd line of treatment for those non-responsive to SSRI's -they habe an advantage of targeting more than one neurotransmitter. -BUT they have greater side effects so only used as a 2nd line treatment if SSRI's aren't effective

Answer 9

Clomipramine - 1st medication approved for OCD

Answer 10

increase serotonin and noradrenaline by blocking their reuptake, causing increase I'm levels of these transmitters at the synapse. -they act at various other receptors (makes them less selective) so can contribute to clinical efficiency and also side effect

Answer 11

Has more servere side effects that SSRI's, so used only for those who don't respond to SSRI's and SNRI's

Answer 12

Valium and diazepam

Answer 13

increase activity of neurotransmitter GABA (gamma-aminobutyric) which is an inhibitory neurotransmitter, which calms and reduces activity of neurons -when GABA docks at the receptor site of a neuron, it makes it less likely to fire an action potential

Answer 14

commonly used to reduce anxiety

Answer 15

P: drug therapy is more cost effective and less disruptive on patients life compared to talking therapies Eg: As SSRIs are cheaper than talking therapies it has economic implications for the UK. It is better for the NHS as it could reduce the financial pressure on an already struggling public service Ex: Drug therapies are also less disruptive on a patients life. The patient just needs to take one tablet a day compared to attending weekly sessions and completing homework for CBT Cou: However, a systematic review by Skapinakis et al. (2016) found that cognitive and behavioural (exposure) therapies were more effective than SSRIs for OCD L: For these reasons drug therapies can be the preferred treatment for many patients, however, increased efficacy of SSRIs may be a better long term solution P: drug treatment has considerable supporting evidence Eg: Eg: Soomro et al (2009) reviewed studies comparing SSRIs to placebos in the treatment of OCD and concluded that all 17 studies (meta-analysis) showed significantly better results for the SSRI groups in the short term Ex: This supports the argument that biological treatments are effective as on average 70% of OCD patients had improved symptoms with drug therapy, also suggesting serotonin has a role in the development of the disorder. Cou: However, a limitation of the studies is that they were typically 3-4 months long and therefore there is little data on the long-term effects of drug therapy. L: suggests that randomized, double-blind clinical trials of SSRIs of 12 months or longer to establish whether efficacy observed in shorter trials is maintained, and whether additional side effects emerge

Answer 16

P: drug therapy often has unpleasant side effects Eg: Even first line treatments such as SSRIs can cause indigestion, blurred vision and a loss of sex drive. Clomipramine can also cause more serious problems: more than 1 in 10 experience erectile dysfunction and weight gain; 1 in 100 become aggressive and experience heart-related problems. Ex: Ashton (1997) recommends that drugs for OCD are used for no longer than 4 weeks due to the side effects. L: It could therefore be argued that drug therapies are therefore not an effective long- term treatment for OCD. P: drug treatments are critisized for treating the symptoms of the disorder and not the cause Eg: Koran et al. (2007) suggest that psychological treatments such as CBT may be a more effective long-term solution to provide a lasting treatment and a potential cure Ex: because although SSRIs work by increasing the levels of serotonin in the brain, which reduces anxiety and alleviates the symptoms of OCD, but it does not treat the underlying cause of OCD. Furthermore, once a patient stops taking the drug, they are prone to relapse L: suggests that the biological issues that drug treatments are intended to target may not be fundamental to the disease, so only have symptomatic effects. This means that the use of drug therapy is only a temporary treatment for OCD, and that the biological causes of the disease may be unknown.

Answer 17

use of SSRIs eg fluoxetine acts to inhibit the re-uptake or re-absorption of serotonin in the brain enabling the serotonin to remain active at the synapse where it continues to stimulate the post-synaptic neuron

Answer 18

as a result of allelic variation, individuals have different physical manifestations; these manifestations can affect psychological functioning, where the proteins involved impact brain function

OCD Flashcards

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