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PSYCHOPATHOLOGY- the biological approach to explaining and treating OCD -…
PSYCHOPATHOLOGY- the biological approach to explaining and treating OCD
the biological approach to explaining ocd
ocd is due to faulty physical processes. physical structure of dna, inherited from parents. dna codes for other aspects of biology, including how neurotransmitters are processed in the synapse and the development and functioning of larger structures like brain regions
the genetic explanation
predisposition is inherited from parents.
genetic analysis revealed around 230 separate "candidate genes" found frequently in people with ocd. many influence the functioning of neural systems in the brain, like how the SERT gene affects reuptake in the serotonin system. other identified genes include COMT gene and more.
because so many have been identified, it suggests OCD is polygenic, meaning a predisposition to ocd requires a range of genetic changes.
POSITIVE EVIDENCE- family and twin studies. ocd is only abour 2% in population. this means the concordance rate between and OCD patient and a stranger are also 2%. But, with ocd, the closely genetically related 2 people are, the higher the concordance. Identical twins have 68% concordance rate, first degree relatives have 10% concordance rate.
the neural explanation
include biochemical causes (inbalance of neurotransmitters)and the large neural structures in the brain made up of many neurons
serotonin
low levels thought to cause obsessive thoughts. believed to be low because being removed too fast from synapse before it has been able to transmit signal to post synaptic cell
presynaptic neurons release neurotransmitters the the receptors in the postsynaptic neuron detect these.
if signal is strong enough then the message is passed on. the neurotransmitters detatch frm the receptors and are taken back to the presynaptic neuron through a process called reuptake.
its thought this process happens too quickly in people with ocd, leading to reduced serotonin levels in the synapse
SERT gene is responsible for serotonin transportation in the synapse
neural structures
the "worry circuit" is a set of brain structures including the orbitofrontal cortex, the basal ganglia system and the thalamus
communication between these appears to be overactive in those with ocd
in normal functioning, the basal ganglia filter out minor worries coming from the orbitofrontal cortex but if the area is overactive then small worries get to the thalamus, which is then passed back to the orbitofrontal cortex which forms a loop and therefore reoccuring obsessive thoughts
compulsions are an attempt to break the loop which creates temporary relief but the hyperactive basal ganglia will soon resume worry circuit
parahippocampal gyrus is an area of cortex close to hippocampus on brains underside and also linked to ocd. responsible for regulating and processing unpleasant emotions and has been seen to function abnormally in cases of ocd
evaluating the biological approach to explaining ocd
POSITIVE- the high concordance rate between close family members shows genetic link. non-identical twins- 31%, identical- 68%. MZ and DZ twins share same enviroment growing up so additional concordance rate suggests its genetic
NEGATIVE- correlation in family and twin studies doesnt automatically equal causation. might not be genetics responsible for the concordance rates, closer family members will have more similar enviroments. identical twins are more likely to be treated more similar than non-identical twins because they look alike. concordance rate isnt 100% so there must be some role in the ebviroment
NEGATIVE- maybe a diathesis-stress model would be more appropriate. this would say that people have a genetic vulnerability but the disorder wont develop unless theres an enviromental stressor, like a traumatic life experience. cromer showed over half of ocd patients reported a traumatic life event and these people reported increased severity of ocd symptoms which demonstrates the enviromental aspect of ocd
POSITIVE- neuroimagine studies using PET scanners have shown hyperactivity in the orbitofrontal cortex and the caudate nucleus in people with ocd both while scanning the brain at rest and when symptoms are stimulated. however the issue with neural evidence is that it is correlational- cant see if these hyperactivities are a cause or a concequence of having ocd
POSITIVE- meta-analysis demonstrated SSRIs are more effective than placebos which suggests theres a biological element to ocd
NEGATIVE- however, even though these drugs immediately alter the amount of serotonin in the synapse, the drugs take weeks to reduce symptoms and 40-60% patients only show partial improvement. suggests that low serotonin levels arent the sole cause of ocd
the biological approach to treating ocd- drug therapy
SSRIs
these are the primary class of drugs used to control the symptoms of ocd and theyre a group of antidepressant drugs, eg prozac.
they only influence serotonin the the brain and slow down the reuptake process in the synapse. serotonin is still present in the synaptic cleft and continues to stimulate the post synaptic neuron. this decreases anxiety by normalising the activity in the worry circuit
can take3-4 months to reduce symptoms. not effective for everyone. dosage can be increased or patient can use anti-anxiety drugs like benzodiazepines, which work by enhavcing a neurotransmitter called GABA- slowing CNS and resulting in general relaxation. Tricyclics and SNRIs increase serotonin and noradrenaline which can be effective when SSRIs fail, but because theyre non-selective (work on numerous neurotransmitters then they have more intense side effects
evaluating the biological approach to treating ocd
POSITIVE- meta analysis comparing SSRIs to placebos. over 3000 Ps. Results showed SSRIs significantly reduced ocd symptoms compared to placebos between 6 and 17 weeks post treatment. shows that drug therapy is effective short term (soomro)
NEGATIVE- Goldacre points out that most research done on drug therapies are done by pharmaceutical compaines which means they have a financial interest in showing drugs are effective. this as well as the file drawer effect (many negative results stay unpublished) means the metaanalysis may be skewed and drug therapies may not be as effective as claimed
POSITIVE- drug therapy cheaper and more convenient compared to cbt
NEGATIVE- many dont prefer this method of treatment because of the side effects. Soomro's meta alalysis found headaches and insomnia were common side effects. can take 4 months to reduce symptoms and patient can become dependent on the drugs
NEGATIVE- only treat symptoms rather than the cause. argued that serotonin inbalance is a result of ocd and not the cause. this means the origin could be due to a traumatic experience Cromer results (54% reported traumatic life event). suggests that psychological therapies that address life events might be better long term treatment