OCD

• OCD


  This involves:

  • Thoughts are urges that are intrusive and unwanted (obsessions)
  • Need to engage in repetitive behaviours or mental acts (compulsions)

  obsessions, which are cognitive is linked with compulsions, which are behavioural
• Behavioural symptoms of OCD


  • Repetitive and ritualistic acts carried out to minimise the distress that obsessions trigger
  • Compulsions

  e.g. extensive hand washing, cleaning, checking, ordering, counting, praying, reciting
• Emotional symptoms of OCD


  • Severe anxiety and distress caused by obsessions
  • Guilt after an episode
• Cognitive symptoms of OCD


  • Persistent, unintentional and unwanted thoughts
  • Highly intrusive and distressing urges
  • Attempt at suppressing irrational thoughts but find it difficult

  e.g. concerns about germs and contamination, doubts, order and symmetry
• Genetic explanation of OCD


  People with first degree relatives with OCD are 5x more likely to develop it than general population - genetic factors play a part
• Twin study meta analysis 


  MZ twins are twice as likely to develop OCD if their co-twin has it compared to DZ twins

  Concordance rate for MZ= 68%, DZ= 31%

  Strong evidence for a genetic link

  However there are other factors as rate is not 100%
• MZ


  Monozygotic twins (identical)

  Share 100% genes 100% environment
• DZ


  Dizygotic twins (non-identical)

  Share 50% genes 100% environment
• Candidate genes


  Through research, these are implicated in the development of OCD
• Examples of candidate genes

  SERT - regulating serotonin (neurotransmitter that transmits mood related information across synapses)

  COMT - regulating production of dopamine (neurotransmitter that affects motivation and drive)
• Neural explanations


  Abnormal levels of certain neurotransmitters / Abnormal brain circuits can cause OCD symptoms
• How does low levels of serotonin link to OCD?


  Dysregulation of mood and the transmission of mood-relevant information

  Neurotransmitters aren't transferring information properly between neurones
• Neuroimaging techniques in OCD


  Brain scans, allows comparison between normal and abnormal brain patterns
• What have researchers found about the basal ganglia relating to OCD?


  Basal ganglia - innate psychomotor functions (movement / reflex)

  Hypersensitivity of the basal ganglia can lead to repetitive motor behaviours seen in OCD, such as repetitive washing / cleaning / checking
• What have researchers found about the orbitofrontal cortex and thalamus relating to OCD?


  OFC - decision making and worry about social and other behaviour

  thalamus - cleaning, checking and other safety behaviours

  Overactive OFC result in increased anxiety and increased planning to avoid anxiety

  Overactive thalamus result in increased motivation to clean or check for safety

  Both linked
• Strengths and weaknesses of genetic explanations of OCD


  • Strong evidence
  • Close relatives may have observed and imitated behaviour
  • Nature vs Nurture
  • Too many genes involved in OCD (polygenetic) - difficult to pin down all involved
  • No real predictive power - cannot be used for diagnosis
  • Individuals may have a vulnerability towards OCD, triggered by an environmental stressor - should we focus on environmental causes instead?
• Strengths and weaknesses of neural explanations of OCD


  • Allows medication development
  • Drugs are not completely effective
  • Ignores the underlying cause
  • Time delay between drug taking and noticeable improvements
  • Many supporting evidence
  • Cause and effect issue
  • Inconsistencies
  • Doesn't explain obsessional thoughts
• Co-morbidity 


  The simultaneous co-existence of multiple disorders alongside a primary disorder diagnosis (e.g. depression, anxiety, schizophrenia, addiction)
• Drug therapy 


  • Aims to correct a chemical imbalance in the brain
  • Increase or decrease the levels of neurotransmitters in the brain
• SSRI

  Selective Serotonin Reuptake Inhibitors

  • Increasing certain neurotransmitters in the brain by preventing the re-absorption of serotonin
  • By increasing its levels in the synapse, it continues to stimulate the post-synaptic neurone, brain can return to effective communication

  A) Synapse

  B) Serotonin

  C) SSRI

  D) Receptor

  
• Drug therapy with CBT


  By taking drugs, sufferer's emotional symptoms can be reduced, which means they can engage more effectively with CBT

  These treatments combined is often helpful for people with depression
• Alternatives to SSRIs


  • Tricyclics (not commonly used anymore due to worse side effects)
  • SNRIs increase serotonin + adrenaline levels)
• Strengths and weakness of drug therapy 


  • Cost effective and non disruptive
  • Side effects (slow process to come off dosage reduced through a period of 6 months)
  • Only treating the symptoms not the cause can lead to relapse
  • Unreliable evidence
  • Trauma not addressed
• Fineberg et al - escitalopram for OCD


  Aim: Access the efficacy of escitalopram as a biological treatment for OCD

  Procedure: 320 people with OCD test out either the drug escitalopram or a placebo on a double-blind basis

  Findings: after 24 weeks 52% of the placebo group and 23% of the escitalopram group reported a recurrence of their OCD symptoms
• What are the benefits of a double-blind trial?


  Neither p's nor researchers know if drug is placebo or real, this prevents bias
• Why is it important to allocate drugs to different participants randomly?


  Ensures a spread of OCD symptoms severity across both placebo and real drug groups