Explanation

• The biological explanation (genetic and neural)

  • people inherit a genetic vulnerablity that can be triggered and lead to OCD
  • Lewis found evidence that OCD runs in families: 37% patients had parents with OCD and 21% had siblings with OCD
  • likely that a genetic vulnerablity requires a trigger such as an environmental stressor
• OCD is thought to be polygenic. This means it is caused by a combination of genetic variations that increase vulnerablity. There is evidence that genes assosciated with the activity of dopamine and serotonin are involved.

  • one variation of the COMT gene results in higher levels of dopamine
  • SERT gene affects the transport of serotonin causing lower levels of serotonin which is also assosciated with OCD
• Neural explanations see OCD as resulting from abnormal functioning brain mechanisms. The focus is on neurotransmitters and brain structures.

  Research suggests that OCD involves provlems in communication between the orbitofrontal cortex and basal ganglia. These brain structures use serotonin. PET scans show how low levels of serotonin in the brains of OCD patients exist. Anti depressant drugs which increase serotonin are often effective in reducing OCD
• PET scans also show higher activity in the orbitofrontal cortex in people with OCD. This is a region of the brain which converts sensory information into thoughts and actions. Heightened activity will increase the conversion of sensory information to actions which will result in compulsions. The increased acitivty leads to difficulties in switching off or ignoring impulses.
• Dopamine levels are thought to be abnormally high in b.g.

  Basal ganglia is linked to motor control and higher levels of dopamine have been assosciated with compulsive behaviours.

  There is some evidence to suggest that the parahippocampal gyrus, assosciated with processing unpleasant emotions, functions abnormally in people with OCD.
• A03- Supporting evidence

  Nestadt et al (2010)

  • review of twin studies
  • found higher concordance rates for MZ twins who had 68% vs DZ who had 31%
  • thus showing a high genetic component for OCD
  • however the evidence for MZ twins is not 100% and therefore cannot be the only reason as to why OCD develops, and so suggests that other factors must also play a role
• A03- Weakness

  • A weakness of the biological approach to explaining OCD is that is can be considered biologically reductionist
  • It does not take into account non biological factors such as cognitions, mental processing and learning through past trauma. For example, compulsions such as handwashing may be a learned process in response to feeling contaminated.
• A03 - Value

  • Allowed for the development of treatment
  • If OCD is due to a chemical imbalance, the implication is that this imbalance can be corrected through the use of medication
  • For e.g. anti-depressants can be used to increase the level of serotonin in the communication between the orbitofrontal cortex and the basal ganglia
  • Anti anxiety drugs have also been used to deal with the anxiety and distress that persistent intrusive thoughts can lead to, which shows the value of the biological approach (helping individuals with their OCD so it does not hinder everyday functioning.)
• A03 - Supporting evidence

  Hu (2006)

  • Compared serotonin activity in 169 OCD sufferers and 253 non-sufferers
  • Serotonin levels were found to be lower in OCD patients
  • Thus supporting the idea of how low levels of serotonin are assosciated with OCD