ocd

• What percentage of the UK suffers from OCD?

  1-3% (statistical infrequency)
• What is the definition of OCD?

  disorder in which a person has recurrent and unwanted thoughts, a need to perform repetitive and rigid actions, or both (obesessions+compulsions)
• What is it called when a patient just experiences obsessional thoughts?

  Pure O
• What is the definition of an obsession?

  Repetitive, intrusive, internal thoughts that cause anxiety
• What is the definition of a compulsion?

  Compelling, rigid, external actions that reduce anxiety when carried out
• What are the behavioural symptoms of OCD?

  • Compulsions

  Performing repetitive behaviours (e.g, cleaning)

  • Avoidant behaviour
• What are the cognitive symptoms of OCD?

  • Obsessions

  Hypervigilance - high alert on dangers in surroundings

  Catastrophic thoughts - irrationally exaggerating danger

  Selective attention - especially attending to anxiety stimulus
• What are the emotional symptoms of OCD?

  • Caused by obsessions

  Depression/Anxiety/Distress
• Outline the genetic explanation for OCD

  Increased vulnerability to OCD due to inherited levels of COMT gene (dopamine neurotransmitter linked with pleasure) - high = OCD because negative reinforcement of reducing anxiety - + SERT gene (serotonin neurotransmitter linked with happiness) - low = OCD because increases anxiety due to obsessions
• What is the definition of polygenic and how is OCD polygenic?

  • Characteristics determined by two genes - COMT + SERT gene

  EVIDENCE: Taylor carried out a meta-analysis that found as many as 230+ genes implicated in OCD
• What is the definition of a candidate gene?

  Gene related to a particular trait

  e.g, disease
• What is the definition of the diathesis-stress model?

  Theory that suggests psychological disorders are the result of inherent vulnerability and environmental stressors
• What is the evidence in twin studies to support the genetic explanation of OCD?

  Gerald Nestadt al. - 68% of monozygotic (identical) twins shared OCD as opposed to 31% in dizygotic (non-identical)

  • Concordance rates high = genetic implication of OCD

  As MZ is not 100% there must be environmental factors as well
• What is brain imaging and why is it useful?

  Measures the activity of blood flow to the brain when performing the test

  e.g, FMRI + PET scans
• How does OCD link to the physiology of the brain?

  • Overactive thalamus = increased motivation to clean + check for safety (compulsions)
  • Overactive OFC = increased anxiety from obsessions + increased planning to avoid anxiety
  • Damaged caudate nucleus = no suppression of minor signals so 'worry signals' are more intense
• What role does the thalamus have on behaviour?

  Safety + checking + cleaning behaviours

  • Found in basal ganglia
• What role does the orbitofrontal cortex (OFC) have on behaviour?

  Cognitive - decision making

  • Prefrontal cortex
• What role does the caudate nucleus have on behaviour?

  Regulates signals / suppresses minor signals between the thalamus and OFC

  • Found in basal ganglia
• How do serotonin and dopamine relate to the physiology of the brain?

  Dopamine is the main neurotransmitter of basal ganglia

  High levels = overactivity of area: less regulation of signals (caudate nucleus) and more hypervigilance (thalamus)

  Serotonin deficiency initiates faulty signals from OFC + linked to malfunction of the caudate nucleus
• What is the worry cycle?

  -> OFC sends worry signal to thalamus -> Caudate nucleus monitors signals between OFC + thalamus -> thalamus sends filtered version of danger back ->