biological approach to explaining and treating ocd Flashcards
genetics
biological explanation for ocd is that it is inherited through genes
gene mapping indicates that a single ocd gene doesnt exist, it is polygenic
over 230 genes involved in increasing risk
evidence from twin studies comparing concordance rates between mz and dz twins. if pure genetics, expect 100% concordance rate
carey and gottesman 1981
genetic factors have a role in the development of ocd
concordance rates in mz (87) v dz (47)
however, genetic factors alone cannot explain development of ocd as CR dont match genetic similarity
neural explanations
another explanation for ocd is the role of neurotransmitters thought to be influenced by a number of genes
dopamine
levels regulated by the COMT gene
faulty variation of this gene leads to increased levels of dopamine travelling across the synapse to the post-synaptic receptors, which has been linked to ocd
particularly development of compulsions
serotonin
levels regulated by SERT gene
faulty variation of this gene leads to lower levels of serotonin travelling across the synapse to the post synaptic receptors, which has been linked to ocd
particularly the development of obsessions
faulty brain structure
orbitofrontal cortex known to play a role in ocd
region in front of brain resposible for converting sensory information into thoughts and actions
pet scans have found higher activity in the orbitofrontal cortex in patients with ocd
research has shown that this increased activity in the orbitofrontal cortex causes sufferers to have difficulties with ignoring impulses so they develop into obsessions
genetics strength 1
supporting research evidence
nestadt et al 2010
reviewed twin studies and found that 68% of identical twins shared ocd as opposed to 31% dz twins
this strongly suggests a genetic influence on ocd
genetics strength 2
supporting research evidence
nestadt et al 2010
found that antidepressants that work purely on the serotonin system are effective in reducing ocd symptoms
strongly suggests that neural mechanisms
genetics limit 1
biologically determinist
environmental risk factors can also trigger or increase the risk of developing ocd
cromer et al found that over 50% of ocd patients in their sample had a traumatic event in their past, and ocd was more severe in those with one or more traumas
causes us to question the validity of biological interactions as its clear ocd is far more complex than just biological components and rather an interactionist approach which values both environmental and biological influences is best
genetics limit 2
other alternative explanations for ocd
this is because the two process model can be applied to ocd. for example, a neutral stimulus (such as dirt) is associated with anxiety. compulsive behaviours (handwashing) maintain the association by negative reinforcement (by washing their hands it takes away the anxiety)
for example, albucher et al 1998 report that most adults with ocd improved considerably after using exposure and response prevention (erp) a treatment where patients experience their feared stimulus and are prevented from performing their compulsive behaviour
this suggests that because exposure and response prevention is successful ocd has psychological as well as biological causes
drug therapy
aim to change levels of neurotransmitters in the brain
antidepressants
e.g. prozac
used to treat ocd
increase levels of serotonin associated with ocd
taken daily and in capsules or liquid
ssris
serotonin released into synapse by pre synaptic neuron
serotonin travels across synapse to the post-synaptic receptor sites
serotonin then travels back to pre-synaptic neurone and would normally be reabsorbed so it can be broken down and reused
this reabsorption is prevented
by blocking reabsorption more serotonin is left in the synapse and more reaches the post synaptic neuron
anti anxiety drugs
e.g. valium
used to treat ocd
help adjust neurotransmitter levels so person feels less anxious
how do anti anxiety drugs work
slow down activity of cns by increasing levels of GABA which has a general relaxing effect on the neurones responsible for making a person feel anxious
reduce brain activity and in turn reduces impact of dopamine
strength 1 biological treatments
effective
soomro et al 2009 reviewed 17 studies comparing ssris to placebos in treatment of ocd. all 17 studies showed significantly better results for ssris than for the placebo conditions
effectiveness is greatest when ssris are combined with a psychological treatment usually cbt.
typically symptoms reduce for around 70% of patients taking ssris, the rest are helped by alternative drugs or cbt + drugs. so drugs can help most patients with ocd
bio treatments strength 2
drug therapies are preferred to other treatments
this is because they are cost effective and non-disruptive
drug therapies involves little input from the user in terms of effort and time, and require little monitoring by doctors. in contrast, therapies such as cbt require patients to attend regular meetings and put considerable thought into tackling their problems, as well as requiring therapists time
these benefits mean that drug therapies are more economical for the health service than psychological therapies
bio treatments limit 1
some patients will suffer from side effects such as indigestion, blurred visions and loss of sex drive.
for patients taking clomipramine side effects can be more common and more serious and patients will suffer from erection problems, weight gain, become aggressive and suffer disruption to blood pressure and heart rhythm
such factors reduce effectiveness because people stop taking the medication
bio treatments limit 2
effectiveness may be exaggerated by publication bias
turner et al 2008 claimed there is a publication bias towards studies that show a positive outcome of antidepressant drugs in treatment of ocd
consequence of this publication bias is that research may exaggerate beneficial effects of these drugs
drugs companies also have a strong interest in success of their products and much of the research funded these companies. selective publication can lead doctors to make inappropriate treatment decisions that may not be in the best interest of the patients.
