OCD

• What are 3 behavioural characteristic of OCD?

  • Repetitive compulsions e.g. hand washing/counting
  • Compulsions reduce anxiety

  -Some individuals show compulsions where obsessions are absent with the aim of reducing general anxiety

  -Most individuals show compulsions as a response to an obsession

  • Avoidance.
• What are 3 emotional characteristics of OCD?

  • Anxiety and distress
  • Depression - a low mood
  • Guilt and disgust.
• What are 5 cognitive characteristics of OCD?

  • Obsessions - intrusive and persistent thoughts, images or impulses
  • Cognitive strategies to deal with obsessions e.g. carrying out another task
  • Insight into excessive anxiety - an awareness of the irrationality must be present
  • Catastrophic thoughts
  • Hyper vigilant.
• Brain structure in OCD:


  PET scans reveal high activity in the frontal lobes when carrying out tasks that activate OCD symptoms

  Caudate nucleus is designed to suppress minor worry signals reaching the thalamus from the frontal lobes is damaged e.g. worrying about germs after touching something dirty.
• Neural explanation of OCD; mood affecting neurotransmitters.


  Serotonin - low in sufferers meaning the mood relevant transmission doesn't take place at the neuron.

  -Serotonin is involved in stopping the repetition of tasks.
• Role of genetics in OCD:


  Lewis- observed that of his patients with OCD- 37% had parents with OCD- 21% had siblings.

  OCD may be associated with a rare combination of two mutations within the human serotonin transporter gene (hSERT)

  This cause's increased reuptake of serotonin in those neuronal synapses and hSERT works too fast and may collect all the serotonin before the next cell has heard the signal to absorb the transmitter, decreasing the

  amount of serotonin available in the synapse for signalling.

  -Leads to less serotonin being available for neuronal communication
• What is a weakness of OCD?

  Many neural mechanisms have been identified but these are not aways present in all cases - point towards the idea that structural abnormalities in the brain may be a symptom rather than the cause of the illness.
• Researchers know that oCD is triggered by communication problems between the brains deeper structures and the front part of the brain. These parts of the brain primarily use serotonin to communicate.
• What is a weakness of OCD?

  Genetics - Billet - MZ twins (68%) are more likely than DZ twins (31%) of sufferers with OCD.

  Specific candidate genes have been found to increase the genetic vulnerability of OCD.

  -37% had parents with OCD

  -21% had siblings

  Concordance rates in twins should be 100%.
• What is a weakness of OCD?

  Genetics - Nestadt - found you are 5 times more likely than the general population if a first degree relative sufferers.

  -Might be higher for first degree relatives - environment.
• What is a weakness of OCD?

  Genetic explanations have poor predictive validity - too many candidate genes involved.

  Difficult to isolate OCD onto a specific gene- more likely to be polygenic.

  the gene doesn't just affect OCD- may have a genetic vulnerability.

  -Genetics are unlikely to be a useful explanation in the onset of OCD.
• What is a biological treatment of OCD?


  Selective serotonin reuptake inhibitors (SSRIs) - Serotonin is released by pre-synaptic neurons and travels across the synapse to the post-synaptic neurons - it is then re-absorbed by pre-synaptic neurons. SSRIs prevent this re-absorbtion so that they continue to stimulate the post-synaptic neurons - this reduces OCD symptoms.

  -E.g. Prozac.
• What is a biological treatment for OCD?

  Benzodiazepines (BZs) - Benzodiazepines enhance the effect of neurotransmitter gamma-aminobutyric acid (GABA)

  -GABA stops other brain chemicals exciting the neuron reducing activity and brain arousal

  This has a sedative effect and can reduce compulsions.

  -e.g.Valium.
• What are strengths of biological treatments fro OCD?

  Research to support - Julien study: SSRIs reduce OCD symptoms ni

  50-80% of cases, allowing a fairly normal lifestyle

  Litlle effort from the patient and NHS. Time -DS and CBT take much longer.
• What are weaknesses of biological treatment of OCD?

  • Patients' experience: can exhibit withdrawal symptoms even with LOW doses of Benzodiazepines

  -This indicates a psychological dependence.

  • Tolerance- taken over a long period you can find yourself needing an increased dose to get the desired effect
  • Side effects; nausea, headaches, insomnia.
  • There is evidence that SSRIs work better alongside CBT in many cases and sometimes CBT works better than SSRIs
  • Only lasts as long as the person takes the drug because the problem itself has not been addressed.