OCD

• What is the COMT gene associated with in terms of dopamine levels?

  One variation of the COMT gene results in higher levels of dopamine.
• In which patient population is the variation of the COMT gene that results in higher dopamine levels more common?

  It is more common in patients with OCD, particularly those with compulsive behaviors.
• The SERT gene- Affects the transport of the neurotransmitter serotonin. Transportation issues cause lower levels of serotonin to be active within the brain and are associated with

  OCD
• Behavioural characteristics:

  • compulsions are repetitive
  • compulsions are performed to reduce anxiety
  • Avoid situations that trigger anxiety
• Emotional characteristics:

  Anxiety/distress caused by compulsions/obsessions

  Accompanying depression

  Guilt and disgust directed at something or self.
• Cognitive characteristics

  obsessive thoughts

  Cognitive coping strategies

  insight into excessive anxiety

  e.g hypervigilance
• OCD- a condition characterised

  by obsessions and/or

  compulsions

  obsessions=cognitive

  compulsions=behavioural
• Neural explanations:

  Neurotransmitters serotonin and dopamine

  are believed to play a role in 0CD

  Piggot et al: Antidepressants that increase serotonin caused

  a reduction in OCD symptoms, whereas those

  who didn't have them had no effect
• Role of structures in the brain:

  orbitofrontal cortex relays info about things that are

  worrying and converts into actions. PET scans showed

  higher OFC activity inpatients with OCD , possibly linking to

  explaining compulsions
• What does the diathesis-stress model suggest about the development of OCD?

  It suggests that genes alone are not solely responsible for the development of OCD.
• What does the term "diathesis-stress" refer to in the context of OCD?

  It refers to the idea that genetic vulnerability interacts with environmental stressors to determine the condition that develops.
• Which types of environmental stressors might influence the development of OCD according to the diathesis-stress model?

  Examples include death and divorce.
• What are the key components of the diathesis-stress model in relation to OCD?

  • Genetic vulnerability (diathesis)
  • Environmental stressors (e.g., death, divorce)
  • Interaction between genes and environment determines the development of OCD
• Diathesis-stress model:

  It is highly unlikely that genes are solely

  responsible for the development of OCD

  as the condition is too complex

  Diathesis Stress means that having the

  genes produces a vulnerability but

  environmental stressor determines the

  condition that develops

  eg death, divorce etc
• A03 genetic explanation for OCD:

  Strength: Evidence that people are vulnerable to OCD as a result of their genetic makeup.

  Twin studies: Nestadt et al (2010) reviewed previous twin studies and found that 68% of identical twins shared OCD as opposed to 31% of non-identical twins.

  Therefore suggests a strong genetic influence on OCD
• A03 genetic explanations for OCD:

  limitation: However there is research support to show the impact of environmental factors acting as a trigger or increasing the risk of developing OCD. (supporting Diathesis model)

  Cromer et al (2007) found that over half of the OCD patients in his sample had a traumatic past and that OCD was more severe in patients with more than one trauma.

  Therefore this suggests OCD may not be entirely genetic in origin. Therefore may be more important to focus on the environmental causes because these are easier to do something about.
• A03 genetic explanation for OCD:

  Issues with understanding neural mechanisms in OCD

  While there is evidence to support the abnormalities in the orbitofrontal cortex, research has also identified other areas of the brain that are involved sometimes.

  This means there is no brain system which has consistently been found to play a role in OCD

  Therefore there cannot be a cause and effect relationship concluded, since it is difficult to confirm whether the biological abnormalities are a cause of OCD or a result of the disorder.
• Biological treatments for OCD: aim to regulate neurotransmitters in our brain
• selective serotonin reuptake Inhibitors (SSRIs):

  type of antidepressant that acts on the serotonin system to increase levels
• In normal circumstances serotonin is

  released from vesicles into the synapse from

  the Presynaptic neurone.

  It then diffuses across the synapse

  until it reaches receptor sites where it is

  converted back into an electrical impulse

  serotonin is then reabsorbed back into pre synaptic neurone
• In people with 0CD:

  Less serotonin is being released

  Or is being reabsorbed too quickly
• How SSRIs work:

  1. They are designed to block the reuptake

  of serotonin, therefore increasing the levels

  in the synapse

  2. This results in higher likelihood of serotonin

  binding to the receptors on the post-synaptic

  neurone

  3. compensating for the lack of serotonin that would

  naturally be in the individuals system
• Alternatives to SSRIs

  If they aren't effective dosage can be increased or other

  drugs can be used,

  SNRIs: increase levels of serotonin and non adrenaline

  Drug treatments are also used alongside CBT, the drugs reduce

  the persons emotional symptoms, making CBT more effective

  as they engage better.
• A03 for treatments of OCD

  Strength: Research support for their effectiveness

  Soomro et al conducted a review of research examining the effectiveness of SSRIs and found them to be significantly more effective than the placebos in the treatment of OCD across 17 different trials.

  Increases credibility, however studies have been criticised for only concluding the short term effectiveness of drug treatments.
• A03 for treatments for OCD

  Strength: SSRIs are preferable to other treatments

  Drug therapy require little input into time and effort compared to CBT where patients have to attend regular meetings which may interrupt their lives

  Drug therapies are also cheaper for the health service because they require little monitoring.

  Therefore drug therapies are more economical and more attractive to patients, making them a popular choice all around
• A03 for treatments for OCD

  Weakness: drug treatments are criticised for treating the symptoms of a disorder not the cause.

  SSRIs work to increase serotonin levels which reduces anxiety and alleviates the symptoms of OCD but doesn’t fix the underlying cause. This means that when a patient stops taking the drug they are prone to relapsing

  Therefore psychological treatments such as CBT may be more effective as they provide an effective long term solution and potential cure.
• A03 for treatments for OCD

  Weakness: Drugs can have side effects

  Nausea, headaches and insomnia are common side-effects of SSRIs. Side effects of benzodiazepines include increased aggressiveness and long term impairment of memory, some patients also struggle with addiction.

  Therefore these side effects can result in patients not wanting to take them limiting the usefulness and effectiveness of drugs  as a treatment of OCD