Genetic

• Lewis (1936)

  • 36% of his OCD patients had parents with OCD too
  • 21% had siblings with OCD
  • Suggests that OCD runs in families
• Diathesis stress model

  • Might be passing down genetic vulnerability instead
  • Can be triggered by environmental stress
• Candidate Genes

  • Create vulnerability for OCD
  • Some are involved in regulating serotonin systems
  • EG, 5HT1-D beta is implicated in the efficiency of transport of serotonin across the synapse
• OCD is Polygenic

  • Caused by several genes

  Taylor (2013)

  • up to 230 genes may be involved
  • Genes associated with dopamine and serotonin
• Strengths

  • Good supporting evidence - Nestadt et al (2010) showed that 68% of identical twins shared OCD and 31% of non identical twins did. However, the concordance rate isnt 100% so is only a partial explanation
  • Utility - Knowing your at risk of OCD could cause lifestyle changes
• Weaknesses

  • Too many candidate genes - little predictive value as each genetic variation only increases risk of OCD by a fraction
  • Environmental risk factors - Cromer et al (2007) showed that over half of his OCD patients had previous traumatic events. Suggesting its not necessarily genetic