Evaluation of the Biological Approach to Explaining OCD

• strengths

  • evidence for genetic basis- family and twin studies
  • evidence for neural basis
• evidence for genetic basis- family and twin studies

  • family study: Marini and Stebnicki (2012)-> a person with a family member diagnosed with OCD is four times as likely to develop it as someone without
  • twin study: Nestadt et al. (2010)-> reviewed twin studies and found that 68% of monozygotic twins shared OCD as opposed to 31% of non-identical twins
• evidence for genetic basis- family and twin studies COUNTER ARGUMENT 


  twin studies make the incorrect assumption that MZ twins are only more similar than DZ twins in terms of their genes- overlook the fact that MZ twins may also be more similar in terms of shared environments. e.g. DZ twins might be a boy and a girl who have quite different experiences and it could be these experiences that make DZ twins less similar than MZ twins rather than their genes 
• evidence for neural basis 


  there is evidence to support the role of neurotransmitters in OCD

  some antidepressants increase the levels of serotonin and these drugs have been found to reduce the symptoms of OCD- the serotonin system is involved in OCD 

  Menzies et al. (2007)- used MRI to measure brain activity in OCD patients and their immediate family members without OCD and also a group of unrelated healthy people. OCD patients and their close relatives had reduced grey matter in key regions of the brain-> supports the view that anatomical differences are inherited and these may lead to OCD 
• evidence for neural basis COUNTER ARGUMENT

  hard to establish a cause and effect relationship- these biological abnormalities could be a result of OCD rather than its cause 
• limitations

  • no unique neural system
  • alternative explanations
• no unique neural system 


  the serotonin-OCD link may not be unique to OCD

  many people with OCD also experience clinical depression- this is known as co-morbidity (having two disorders together). this depression probably involves disruption to action of serotonin. this suggests that it could simply be that serotonin activity is disrupted in many people with OCD because they are depressed as well and so serotonin may not be relevant to OCD symptoms
• alternative explanations 


  the two-process model can be used to explain OCD

  • classical conditioning= learning occurs when NS (dirt) is associated with UCS (germs) causing anxiety
  • operant conditioning= this association is maintained because the anxiety-provoking stimulus is avoided and they reduce negative reinforcement. obsession is formed and link is learned with compulsive behaviours (hand-washing) that reduce anxiety
  • a treatment called exposure and response prevention is developed based on this model. patients experience feared stimulus and stop performing their compulsive behaviour