Biological treatments for OCD

• What are drug therapies?

  Aims to increase or decrease levels of neurotransmitters in the brain
• What do drug treatments for OCD do?

  Aim to increase serotonin levels in the brain
• What antidepressant drug is used for OCD?

  Selective serotonin reuptake inhibitor (SSRI)
• What do SSRIs do?

  Selectively targets serotonin at the synapse and inhibits the reuptake of serotonin molecules
• Typical dosage for the SSRI fluoxetine (brand name Prozac)?

  20mg
• What do dosages of SSRIs depend on?

  
  

  May be increased if the individual is not feeling a benefit
• How long do SSRIs take to have an impact?

  3-4 months of daily usage of SSRIs
• Step one of the process of SSRIs

  • Serotonin is released by certain neurons in the brain
  • It is stored in vesicles
• Step two of the process of SSRIs

  The electrical signal travelling through the presynaptic neuron causes vesicles to release neurotransmitter into the synaptic cleft
• Step three of the process of SSRIs

  The serotonin molecule chemically conveys the signal from the presynaptic neuron by binding to a postsynaptic receptor site
• Step four of the process of SSRIs

  Afterwards usually serotonin left in the synaptic cleft is reabsorbed into the presynaptic neuron, broken down and reused (reuptake)
• Step five of the process of SSRIs


  If the reuptake sites are blocked by SSRI molecules, this increases the level of serotonin in the synapse as new serotonin is released from the presynaptic neuron
• Step six of the process of SSRIs

  This means that SSRIs effectively increase levels of serotonin in the synapse and therefore continue to stimulate the postsynaptic neuron
• What are SSRIs often combined with?

  CBT
• Why are SSRIs and CBT done together?

  The drugs reduce a person's emotional symptoms, such as anxiety or depression meaning that the individual can engage more effectively in CBT
• Two alternatives to SSRIs

  Tricyclics and SNRIs
• What are tricylics?


  An older type of antidepressant, such as clomipramineThis acts on various systems including the serotonin system Has the same effect as SSRIs More severe side effects than SSRIs, generally kept as a reserve treatment
• What are SNRIs?

  • Selective noradrenaline reuptake inhibitors
  • A different class of antidepressantA second line of defence for people who don't respond to SSRIsIncrease levels of serotonin as well as noradrenaline
• Strengths of drug treatments for OCD

  Strong evidence baseCost-effective and non-disruptive
• Why is "Strong evidence base" a strength of drug treatments for OCD?

  • Soomro's review of 17 studies comparing SSRIs and placebos in treating OCD revealed that SSRIs showed significantly better outcomes
  • With 70% of patients experiencing symptom reduction. The remaining 30% can benefit from alternative drugs or combinations of drug and psychological therapies.
  • This suggests that drug treatments for OCD are effective for that majority of people with OCD
• Why is "Cost-effective and non-disruptive" a strength of drug treatments for OCD?

  • Drug treatments for OCD are cost-effective and efficient, as they can be manufactured quickly, unlike psychological therapy.
  • They are non-disruptive and can be taken until symptoms decline, unlike psychological therapy which requires time spent attending sessions.
  • This makes drugs popular among people with OCD and their doctors.
• Limitations of drug treatments of OCD

  Not the most effective treatment available Serious side effects
• Why is "Not the most effective treatment available" a limitation of drug treatments for OCD?

  • Skapinakis et al carried out a systematic review of outcome studies and concluded that both cognitive and behavioural (exposure) therapies were more effective than SSRIs in the treatment of OCD
  • This suggests that drug treatments for OCD are not as effective as alternative methods
• Why is "Serious side effects" a limitation of drug treatments for OCD?


  • SSRIs benefit most, but a small minority may not benefit.

  • Side effects include indigestion, blurred vision, and loss of sex drive.

  • Tricyclic domipramine side effects are more common and serious.

  • 1 in 10 people experience erection problems, weight gain, aggression, and heart rate problems.

  • These side effects can reduce quality of life and lead to drug discontinuation- .