The biological approach to explaining OCD

• Biological explanations for OCD evaluation:

  • ✅ Evidence from twin studies - meta-analysis found that MZ twins had double the concordance rate for OCD than DZ twins
  • ❌ Ignores other factors - environment
  • ✅ Support for serotonin - when treated with drugs which increase the level of serotonin, symptoms decrease
  • ❌ Alternative two process model - OCD is learnt through classical conditioning. A neutral stimulus is associated with anxiety. An obsessions formed & compulsive behaviours are reinforced when anxiety reduces
  • ✅ Doesn’t blame the sufferer
• The biological approach to explaining OCD:

  • Genetic explanations: the COMT gene, the SERT gene, diathesis-stress
  • Neural explanations: the worry circuit
• Genetic explanations to explaining OCD:

  • COMT gene: regulates dopamine production, associated with higher dopamine levels
  • SERT gene: involved in serotonin transport, lower serotonin levels linked to OCD
  • OCD is a polygenic disorder
  • The diathesis-stress model suggests genetic mutations lead to vulnerability for OCD, but other factors must also be present.
• Neural explanations to explaining OCD:

  • The worry circuit - the caudate nucleus normally suppresses signals from the orbitofrontal cortex which sends signals to the thalamus about worrying. When the caudate nucleus is damaged it fails to suppress minor worries
• Biological explanations for OCD evaluation:

  • ✅ Evidence from twin studies
  • ❌ Ignores other factors
  • ✅ Support for serotonin
  • ❌ Alternative two process model
  • ✅ Doesn’t blame the sufferer