Genetic

• What are the two main candidate genes involved with OCD?

  • COMT gene
  • SERT gene
• What is the COMT gene?

  Responsible for regulating the production of dopamine.
• How is the COMT gene different in people with OCD?

  The variant found in OCD patients is less active so dopamine levels increase because they are less regulated
• What is the SERT gene?

  Affects how the neurochemical serotonin is transported in the brain
• How is the SERT gene different in people with OCD?

  The mutation found in OCD patients causes lower level of serotonin to be present because the brain finds it harder to transport the serotonin
• Strength of the Genetic Explanation:

  Research Support:

  • 68% of MZ twins have OCD
  • 31% of DZ twins have OCD
  • 4 times more likely to have OCD if family member has it.
• Strength of the Genetic Explanation:

  • Environmental risk factor
  • Over half of OCD patients in a sample experienced a traumatic event, and OCD was more severe (Cromer et al)
• Strength of Genetic Explanation:

  • Animals Studies
  • Candidate genes have been found in mice, but can we generalise from animal repetitive behaviour to human OCD?
• Limitation of the Genetic Explanation:

  Twin studies evidence may be flawed - MZ twins share identical DNA but are also treated more similarly than DZ twins
• Limitation of the Genetic Explanation:

  Unable to predict OCD - scientists do not know how many genes are linked to OCD
• Limitation of the Genetic Explanation:

  Incomplete. Diathesis-stress model, studies have found 50% of people with OCD have experienced a traumatic event