Describe and evaluate the biological approach to explaining OCD

Question 1

outline 1

Answer 1

One biological explanation for OCD is that it is inherited through genes.

Gene mapping has been useful in indicating that a single OCD gene doesn’t exist, it is polygenic (associated with multiple different genes) with there being over 230 genes involved in increasing a person’s vulnerability to OCD.

Evidence for the role of genetics comes from twin studies which compare concordance for OCD between MZ and DZ twins.

If OCD was caused by genetics alone, we would expect a 100% concordance between MZ twins as they share 100% of their DNA.

Question 2

outline 2

Answer 2

Another explanation for OCD is the role of neurotransmitters, thought to be influenced by several genes.

Dopamine levels are regulated by the COMT gene.
A 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 the development of compulsions).

Serotonin levels are regulated by the SERT gene.
A faulty variation of this gene leads to lower levels of serotonin travelling to the post-synaptic receptors, which has been linked to the development of OCD (particularly development of obsessions).

Question 3

outline 3

Answer 3

Another explanation is faulty brain structure.

The orbitofrontal cortex is a region in the brain responsible 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 this increased activity causes sufferers to have difficulties with ignoring impulses, so they develop into obsessions.

Question 4

strength genes

Answer 4

Supporting research for the role of genetics comes from Gottesman (1981) who found the concordance rate for OCD was 87% in MZ twins and 47% in DZ twins, suggesting genes have a strong role to play in the development of OCD (but are not solely responsible).

Question 5

strength 2

Answer 5

A strength of biological explanations for OCD is there is supporting research from Nestadt (2010) who found antidepressants that work purely on the serotonin system are effective in reducing OCD symptoms.

This suggests that neural mechanisms including the serotonin system are involved in OCD.

Question 6

limit 1

Answer 6

A limitation of biological explanations however is there is an alternative explanation for OCD.

This is because the two-process model may be applied e.g., a NS (dirt) is associated with anxiety, leading to compulsive behaviours (handwashing) which maintain the association via negative reinforcement.

Albucher et al reported most adults with OCD improved considerably after using exposure and response prevention (ERP), where patients experience their feared stimulus and are prevented from performing their compulsive behaviour.

This suggests that because ERP is successful, OCD has a psychological and biological cause.

Question 7

limit 2

Answer 7

A further limitation is that it is biologically determinist as this explanation suggests all behaviour is caused by internal factors only.

Cromer et al found that over 50% of OCD patients in their sample has a traumatic event in the past and OCD was more severe in those with one or more traumas.

This causes us to question the validity the biological explanations as it is clear OCD is more complex than just biological components and an interactionist approach with both environmental and biological influences is best.