Explaining/Treating OCD

What are the three key assumptions of the biological approach?

behaviour/thought processes have biological basis, all human behaviour is due to genetic makeup/brain structures/chemical processes, human genes have evolved to adapt behaviour to the environment

What are genes that create vulnerability to OCD known as?

candidate genes

What is the SERT gene responsible for and how does it create vulnerability for OCD?

responsible for transfer of serotonin - families with OCD have mutated copies of gene which inhibits ability to carry out function, causing lower levels of serotonin

What is the COMT gene responsible for and how does it create vulnerability for OCD?

regulates dopamine production - found to be faulty in OCD and causes increase in dopamine

What does polygenic mean?

caused by several genes interacting together

What did Taylor find evidence of in their meta-analaysis?

up to 230 genes that may be involved in OCD

How can differences in genetics explain variations in OCD?

same genes may not cause same disorder in each person - aetiologically heterogeneous = number of different combinations of genes can lead to disorder

What is the neural explanation of OCD?

physical/psychological characteristics are determined by the behaviour of the nervous system

Describe the effects of dopamine (the pleasure neurotransmitter).

feelings of pleasure, addiction and motivation - people repeat behaviours leading to dopamine release

Describe the effects of serotonin (the mood neurotransmitter).

contributes to wellbeing/happiness, helps sleep cycle/digestive system, affected by exercise and light exposure

How does the caudate nucleus cause OCD?

regulates attention - leads to decrease in serotonin in people with OCD so they attend more to threats, which is linked to obsessions

How does the parahippocampal gyrus cause OCD?

regulates unpleasant emotions - overactive in those with OCD which creates high anxiety linked to the obsessions

How does the orbitofrontal cortex cause OCD?

worry centre - high dopamine levels in those with OCD, leads to abnormal decision-making to avoid irrational threats/anxiety

How does the basal ganglia cause OCD?

activated by the orbitofrontal cortex, has increased dopamine which causes compulsions

How does the thamalus cause OCD?

high in dopamine in those with OCD, rewards compulsive behaviour, causes feedback loop to OFC to say the threat has been dealt with, thus increasing chances of same action repeating

Give one piece of evidence which supports the genetic explanation of OCD.

Nestadt did meta-analysis of twin studies over long period of time - for identical twins, if 1 had OCD then 68% of time both had it, this was 31% of the time for non-identical twins

Give one piece of evidence which disputes the genetic explanation of OCD.

Cromer found over 50% of OCD patients had traumatic event in past and was more severe in those which had experienced trauma - so caused by environmental factors

Give one piece of evidence to support the neural explanation of OCD.

Julien - 50-80% symptom improvements with SSRIs - but Insel found only 50% improvement

Give another piece of evidence to support the neural explanation of OCD.

Rapoport and Wise used PET scans and found that the caudate nucleus is hypersensitive due to low serotonin, which increases repetitive motor behaviours

How do SSRIs increase levels of serotonin in the brain (so therefore treat OCD)?

prevent the recycling of serotonin so the presynaptic membrane continues releasing serotonin (believes the message still needs to be sent)

Briefly describe the effectiveness of SSRIs in treating OCD?

40-60% improvement but 30-45% remission rate, can take 3-4 months to have an impact, more effective when combined with CBT

Give three side effects of SSRIs as a treatment for OCD?

blurred vision, loss of sexual drive, insomnia

Briefly describe the effectiveness of Tricyclics/MAOIs as a treatment for OCD.

older treatments so prescribed less often

True or False: Tricyclics, MAOIs and SNRIs have more severe side effects than SSRIs as treatments for OCD.

True

Briefly describe the effectiveness of SNRIs as a treatment for OCD.

used for those who don’t respond to SSRIs, also increase noradrenaline - but very expensive and rarely given to under-25s

Give two pieces of evidence to support biological treatments of OCD.

Julien found 50-80% improvement in symptoms with SSRIs, can be treated with alternative drug treatments if SSRIs don’t work

Give two pieces of evidence to dispute biological treatments of OCD.

drugs only treat the symptoms, up to 90% of people relapse when drugs are the only treatment