The biological approach to explaining and treating OCD

• biological approach


  The approach based on what we are made of.
• concordance rate

  The percentage of a family pair who share any given characteristic
• diathesis-stress model

  The idea that people have a genetic vulnerability which is triggered by an environmental stressor.
• MZ twins

  Identical twins who share a complete genotype
• DZ twins

  Non-identical twins who share genes to the same extent as other brothers and sisters
• genome wide association studies


  An approach that involves rapidly scanning markers across the complete sets of DNA, or genomes, of many people to find genetic variations associated with a particular disease.
• inhibitory neurotransmitter

  A neurotransmitter which increases the negative charge of the neuron into which it passes, making it less likely that it will fire
• obsessive thinking

  Repeated thoughts which are unpleasant and which disrupt ordinary processes of thinking
• compulsive behaviours

  Behaviours which arise out of the drive to reduce anxiety.
• serotonin

  An inhibitory neurotransmitter.
• basal ganglia


  A set of structures sitting at the base of the brain which connect with different areas of the brain to form closed signal loops and which help to select among competing thoughts and behaviours.
• orbitofrontal cortex


  A part of the brain which sends worry signals, for example about potential hazards.
• caudate nucleus


  Located in the basal ganglia, it helps to filter irrational and unwelcome thoughts.
• SSRIs

  Selective Serotonin Reuptake Inhibitors - drugs which prevent the reabsorption of serotonin back into the presynaptic neuron and prevent it from being broken down.
• tricyclic antidepressants


  An older type of anti-depressant which works on the serotonin system but has a different mode of action to SSRIs.
• cognitive behaviour therapy

  Therapy that involves a therapist working with a client to challenge irrational thinking and behaviour patterns and to come up with a course of actions which the client will carry out to practise more realistic and helpful thinking.
• side effects


  Reactions to medicine other than the one intended.
• NNT

  Number needed to treat: the number of people who need to be treated for one to make a significant improvement.
• placebo

  A substance which has no effect but which the receiver believes may have an effect.