biological explanation-OCD

• What do genes consist of?

  DNA
• What do genes code for in an organism?

  Physical and psychological features
• How are genes passed to offspring?

  They are inherited
• What determines physical and psychological characteristics?

  Behaviour of the nervous system
• What does the genetic explanation of OCD suggest?

  OCD is partly due to genes
• What percentage of patients with OCD had parents with OCD according to Lewis (1936)?


  37%
• What percentage of patients with OCD had siblings with OCD according to Lewis (1936)?

  21%
• What does genetic vulnerability mean in relation to OCD?

  Being predisposed to develop OCD
• What is the SERT gene associated with?

  Regulating serotonin
• What happens if there are transportation issues with serotonin?

  It can cause low serotonin levels
• What does the COMT gene regulate?

  Dopamine
• What is the relationship between dopamine levels and OCD?

  OCD patients have higher dopamine levels
• What is the diathesis-stress model in relation to OCD?

  Vulnerability through genes plus environmental stressors
• What does it mean that OCD is polygenic?

  Multiple genes determine its development
• What does aetiologically heterogenous mean in the context of OCD?

  Origins of OCD vary among individuals
• What are the strengths of the genetic explanation for OCD?

  1. Strong evidence base for genetic component
  2. Twin studies show high concordance rates:

  • 68% of MZ twins share OCD
  • 31% of DZ twins share OCD

  1. Family history increases risk (4x more likely)
  2. Animal studies link genetic variations to behaviors
• What are the limitations of the genetic explanation for OCD?

  1. Environmental risk factors also play a role
  2. Cromer (2007) found trauma linked to OCD severity
  3. Genetic vulnerability provides only a partial explanation
  4. Diathesis-stress model offers a more comprehensive view
• How might close relatives of OCD sufferers influence behavior?

  Through vicarious reinforcement
• Why should findings from mice studies be generalized cautiously to humans?

  Human minds are more complex than mice
• What is the strength of animal studies in relation to candidate genes for OCD?

  They provide weak support for human relevance