biological explanation of OCD

• OCD

  Obsessive Compulsive Disorder
• Lewis (1936) observed 50 people with OCD at the Maudsley Hospital in London
• 37% of patients had parents with OCD
• 26% had siblings with OCD
• Diathesis-stress model


  Certain genes make people more likely to develop a mental disorder but not certain (environmental stress required to trigger)
• Polygenic


  Not caused by a single gene but by a combination of genetic variations that together significantly increase vulnerability
• Candidate genes contribute to OCD
• Twin studies

  • Nestdat et al. (2010) found 68% of identical twins (MZ) both had OCD as opposed to 31% of non-identical twins (DZ)
• Family studies

  • Marini and Stebnicki (2010) found that if you have OCD in your family you are 4 times more likely to have it than someone who doesn't
• Genetic explanation is only a partial explanation of OCD not the only one
• Environment can also increase risk of OCD
• Environmental risk factors

  • Cromer et al. (2007) found that over ½ of OCD clients have experienced trauma in the past, OCD was also more severe in those with one or more traumas
• Cannot account for OCD in families where there is no previous history
• Taylor (2013) found 230 different genes may be involved with OCD
• Genes studied in relation to OCD are associated with dopamine and serotonin (neurotransmitters that have a role in regulating mood)