OCD

• what type of approach is used to explain OCD?

  biological
• what's the main assumption of the biological approach?

  abnormal behaviour is caused by somethical physical happening in the body
• what are the 2 explanations for OCD?

  1. genetic
  2. neural
• outline the genetic explanation of OCD

  genes create a vulnerability and OCD runs in families

  • diathesis-stress model suggests environment also triggers OCD
  • OCD is polygenic as roughly 230 genes involves
  • aetiologically heterogeneous as different combinations of genes cause different types of OCD
• what are the 2 types of genes involved in OCD?

  1. COMT
  2. SERT
• explain the role of the COMT gene in OCD

  regulates production of dopamine

  • Tukel - OCD has low activity levels of COMT gene and high levels of dopamine
• explain the role of the SERT gene in OCD

  affects efficiency of transporting serotonin and creates lower levels of it
• who studied the link between OCD and families?

  Lewis in 1936
• what did Lewis find out about OCD running in families?

  • 37% of patients had parents with OCD
  • 21% of patients had siblings with OCD
• strength of genetic explanation - research support

  • nestadt et al
  • 68% of MZ twins shared OCD compared to 31% of DZ twins
  • candidate genes increase vulnerability
• outline the neural explanation of OCD

  low levels of serotonin leads to impaired transmission of mood-relevant information

  • linked to low mood and obsessive thoughts
• explain the role of abnormal frontal lobe functioning in OCD


  impaired decision making which leads to symptoms of OCD
• explain the role of abnormal functioning of parahippocampal gyrus in OCD


  increased processing of unpleasant emotions
• explain the role of abnormal levels of neurotransmitters in OCD

  • dopamine is abnormally high
  • serotonin is abnormally low (Pigott - antidepressants reduce symptoms)
• explain the role of abnormal brain circuits in OCD

  high levels of activity in the orbital frontal cortex

  • sends signals to the thalamus about worrying things which leads to an impulse to act
  • struggle to ignore impulses as caudate nucleus is damaged
• strength of neural explanation - supporting evidence

  • brain scan studies
  • increased activity in OFC and basal ganglia
  • neurological basis
• what's the biological treatment for OCD?

  drug therapy
• what's the aim of drug therapies?

  affect levels of neurotransmitters by affecting the activity at the synapses
• outline synaptic transmission in drug therapies

  1. action potential reaches presynaptic terminal
  2. triggers synaptic vesicles to release neurotransmitters into synaptic gap
  3. neurotransmitters diffuse across the gap and bind to postsynaptic receptors
  4. effects are terminated by reuptake
  5. neurotransmitters are taken by presynaptic neuron and stored in vesicles

  
• what are the main 4 types of drugs used to treat OCD?

  1. anti-depressants
  2. alternative anti-depressants
  3. anti-anxiety drugs
  4. antibiotics
• outline anti-depressants as a treatment method for OCD

  SSRIs increase serotonin transmission which normalises circuit

  • abnormal levels in worry circuit damage caudate nucleus
  • suppresses signals to orbital frontal cortex
  • increases impulsive behaviours
• outline alternative anti-depressants as a treatment method for OCD

  if SSRIs aren't effective after 3 to 4 months, dose is increased or combined with another drug

  • tricyclics - more severe side effects (clomipramine)
  • SNRIs - increase serotonin and noradrenaline
• outline anti-anxiety drugs as a treatment method for OCD

  benzodiazepines reduce activity of nervous system

  • enhances activity of GABA
  • slows down activity of central nervous system
  • increases flow of chloride ions which increases relaxation
• outline antibiotics as a treatment method for OCD

  d-cycloserine

  • effective when used with psychotherapy
  • enhances transmission of GABA which reduces anxiety
• strength of drug therapy - effective

  • soomro et al
  • meta-analysis found 70% of patients showed improvements
  • reliable and useful treatment
• weakness of genetic explanation - environment

  • cromer et al
  • over 1/2 of OCD patients experienced traumatic event
  • genetic and environmental influences
• weakness of genetic explanation - lacks comprehension

  • biologically reductionist
  • ignores psychological and cognitive factors
  • need a more holistic approach
• weakness of neural explanation - cause and effect

  • unclear
  • factors could be a consequence of OCD
  • lacks explanatory power
• weakness of neural explanation - insufficient

  • some people don't show serotonin or brain abnormalities
  • not everyone with imbalances develops OCD
  • caused by combination of biological and psychological factors
• weakness of drug therapy - side effects

  • negative side effects
  • e.g. nausea, weight gain and insomnia
  • reduces effectiveness and increases relapse
• weakness of drug therapy - short term

  • only treats symptoms rather than addressing underlying cause
  • doesn't address cognitive distortions or traumatic experiences
  • doesn't provide long-term cure