A03

• Strength = evidence for genetic basis

  • Family study:
  • Marini and Stebnicki (2012) found that an individual with a family member diagnosed with OCD is four times more likely to develop it as someone without
  • Twin study:
  • Nestadt et al. (2010) reviewed twin studies and found 68% of monozygotic twins shared OCD as opposed to 31% of dizygotic twins
• Strength = evidence for neural basis

  • evidence to support role of neurotransmitters in OCD
  • some antidepressants that increase serotonin levels have been found to reduce symptoms of OCD
  • Menzies et al. (2007) used MRI to measure brain activity in OCD patients and their immediate family members without OCD and a group of healthy unrelated people
  • OCD patients and their close relatives had reduced grey matter in key regions of brain supports view that anatomical differences are inherited and may lead to OCD
• Limitation = no unique neural system

  • the serotonin-OCD link may not be unique to OCD
  • many people with OCD also experience clinical depression - referred to as co-morbidity
  • experiencing depression also involves disruption to the action of serotonin
  • suggests it could simply be that serotonin activity is disrupted in many people with OCD because they are depressed
• Limitation = alternative explanations

  • psychological explanations can be used to explain and treat OCD
  • two-process model can be used
  • classical conditioning - learning occurs when NS (e.g. dirt) associated with UCS (e.g. germs) producing anxiety
  • operant conditioning - association maintained because anxiety-provoking stimulus is avoided and they receive negative reinforcement, obsession formed and link learned with compulsive behaviours
  • A treatment called exposure and response prevention (ERP) developed based on the behaviourist two-process model
  • Patients have to experience their feared stimulus and stop performing their compulsive behaviour
  • Studies have supported a high success rate for people with OCD
• What are the strengths of the biological approach to explaining OCD?

  1. Evidence for genetic basis
  2. Evidence for neural basis
• What are the limitations of the biological approach to explaining OCD?

  1. No unique neural system
  2. Alternative explanations