Genetic

• Genetic explanation of OCD

  People inherit specific genes that cause OCD
• Examples of candidate genes

  COMT - regulates the production of dopamine

  SERT - regulates the production of serotonin
• Diathesis-stress model


  Certain genes make people more susceptible to develop OCD but it only develops due to environmental triggers
• Candidate genes

  Genes that are involved in regulating serotonin and create the genetic vulnerability for OCD
• Lewis (1935)

  37% of his OCD patients had parents with OCD

  21% had siblings with OCD
• Tukel et al

  found that one form of the COMT gene is more common in people with OCD - it produced lower activity resulting in higher levels of dopamine
• polygenic explanation

  OCD is caused by several genes
• Taylor (2013)

  found that up to 230 different genes may be involved in OCD
• Positive evaluation of genetic explanation

  • supporting evidence - Nestadt found that 68% of identical twins had OCD compared to 31% of non identical twins
  • Scientific approach - uses rigorous scientific procedures making it highly valid and credible e.g. blood samples
• negative evaluation of genetic explanation

  • family members show different types of OCD Neural- if OCD is inherited, compulsive behaviours should be the same
  • ignores role of environment - no twin studies have found 100% concordance so other factors must be involved - Croner et al found that over half of the patients in their sample with OCD had a traumatic event in their life