Biological approach- treating OCD

• Drug therapy for mental disorders aims to increase or decrease levels of neurotransmitters in the brainer to increase/decrease their activity.
• Drugs to treat OCD work in various ways to increase the level of serotonin in the brain.
• The standard medical treatment to treat OCD symptoms involves a particular type of antidepressant drug called a selective serotonin reuptake inhibitor (SSRI).
• SSRIs work on the serotonin system in the brain. Serotonin is released by certain neurons in the brain. In particular it is released by the presynaptic neurons and travels across a synapse. The neurotransmitter chemically conveys the signal from the presynaptic neuron to the postsynaptic neuron and then it is reabsorbed by the presynaptic neuron where it is broken down and reused.
• By preventing the reabsorption and breakdown, SSRIs effectively increase levels of serotonin in the synapse and this continue to stimulate the postsynaptic neuron. This compensates for whatever is wrong with the serotonin system in OCD.
• Drugs are often used alongside cognitive behaviour therapy (CBT) to treat OCD. The drugs reduce a person's emotional symptoms, such as feeling anxious or depressed. This means that people with OCD can engage more effectively with the CBT.
• In practice some people respond best to CBT alone whilst others benefit more when additionally using drugs.
• When an SSRI is not effective after 3 to 4 months the dose can be increased or combined with other drugs. Sometimes different antidepressants are tried. People respond very differently to different drugs and alternatives work well for some people and not at all for others.
• Tricyclics are sometimes used (e.g. clomipramine). This acts on various systems including the serotonin system where it has the same effect as SSRIs. Clomipramine has more severe side-effects than SSRIs so it is generally kept in reserve for people who do not respond to SSRIs.
• SNRIs have more recently been used to treat OCD. These are a different class of antidepressant drugs and are also a second line of defence for people who do not respond to SSRIs. SNRIs increase levels of serotonin as well as another different neurotransmitter- noradrenaline.
• One strength of drug treatments is good evidence for its effectiveness. There is clear evidence that SSRIs reduce symptom severity and improve the quality of life for people with OCD. Soomro et al. reviewed 17 studies that compared SSRIs to placebos in the treatment of OCD. All 17 studies showed significantly better outcomes for SSRIs than the placebos. Typically symptoms reduce for around 70% of people taking SSRIs, for the remaining 30% most can either be helped by alternative drugs or a combination of drugs and therapies. This means drugs appear to be helpful for most people with OCD.
• However, there is some evidence to suggest that even if drug treatments are helpful for most people with OCD they may not be the most effective treatments available. Skapinakis et al. carried out a review of outcome studies and concluded that both cognitive and behavioural (exposure) therapies were more effective than SSRIs in the treatment of OCD. This means drugs may not be the optimum treatment for OCD.
• What is a limitation of drug treatments for OCD?

  Drugs can have potentially serious side-effects
• How do SSRIs generally affect people with OCD?

  They help most people with OCD
• What percentage of people may not benefit from SSRIs?

  A small minority
• What are some common side-effects of OCD drugs?

  Indigestion and blurred vision
• How long do side-effects from OCD drugs typically last?

  They are usually temporary
• Why can side-effects from OCD drugs be distressing for patients?

  They can be very distressing for people