biological approach to explaining and treating ocd

Question 1

genetics

Answer 1

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

Question 2

carey and gottesman 1981

Answer 2

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

Question 3

neural explanations

Answer 3

another explanation for ocd is the role of neurotransmitters thought to be influenced by a number of genes

Question 4

dopamine

Answer 4

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

Question 5

serotonin

Answer 5

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

Question 6

faulty brain structure

Answer 6

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

Question 7

genetics strength 1

Answer 7

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

Question 8

genetics strength 2

Answer 8

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

Question 9

genetics limit 1

Answer 9

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

Question 10

genetics limit 2

Answer 10

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

Question 11

drug therapy

Answer 11

aim to change levels of neurotransmitters in the brain

Question 12

antidepressants

Answer 12

e.g. prozac

used to treat ocd

increase levels of serotonin associated with ocd

taken daily and in capsules or liquid

Question 13

ssris

Answer 13

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

Question 14

anti anxiety drugs

Answer 14

e.g. valium

used to treat ocd

help adjust neurotransmitter levels so person feels less anxious

Question 15

how do anti anxiety drugs work

Answer 15

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

Question 16

strength 1 biological treatments

Answer 16

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

Question 17

bio treatments strength 2

Answer 17

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

Question 18

bio treatments limit 1

Answer 18

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

Question 19

bio treatments limit 2

Answer 19

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.