OCD Explanations

• The COMT gene - Releases the production of dopamine and had been found to be more common in OCD patients
• The SERT gene - creates lower levels of serotonin which links with OCD
• Diathesis - Stress Model: Genes + Stressor (environmental trigger) is a full explanation for OCD
• Dopamine levels are thought to be abnormally high in people with OCD
• Low levels of serotonin increase OCD symptoms
• High levels of dopamine increase OCD Symptoms
• Neurotransmitters transit messages across they synapse:

  1. Serotonin impulses jump the synapse and lands on a receptor
  2. Message continues into the post-synaptic cell
  3. Serotonin gets reabsorbed into presynaptic cell
• Pauls and Leckman (1986) found that COMT and SERT genes were also present in patients with tourette’s, autism and anorexia so there isn’t a gene specific too OCD

  Therefore not a sole explanation if behaviour
• Comer (2009) - when a patient shot himself in the orbital region his symptoms of OCD subsided

  Provides explanatory power
• Explaining OCD:

  • genetic explanations
  • neural explanations
• Lewis (1936):

  • observed his OCD patients
  • found that 37% had parents with OCD
  • 21% has siblings with OCD
  • Genetic vulnerability is passed through generations
• Diathesis - Stress Model:

  • genetic vulnerability
  • environmental trigger (stressor)
• OCD is polygenic which means it is caused by a combination of genes that significantly increase genetic vulnerability
• Taylor (2013) found evidence that up to 230 different genes may be involved in OCD
• Candidate genes create vulnerability to OCD
• • There are different types of genes that cause OCD and one gene variation or group of genes may cause it in one person, but another sufferer of OCD could have a different variation of genes
• • Tukel et al. (2013) suggested a variation of the COMT gene may contribute to OCD as it is more common in patients who suffer from OCD than in those that do not. This variation produces higher levels of dopamine and lower activity of the COMT gene
• Genetic explanations PEEL 1:

  Strength - research support - Nestadt et al. (2010) reviewed evidence that 68% of identical twins will both have OCD compared to 31% of non-identical twins - suggests there must be some genetic influence
• Genetic explanations PEEL 2:

  Weakness - The Biological approach can't solely explain OCD as the environment also has an effect on whether a person suffers from OCD

  • genetic vulnerability is only a partial explanation
• OCD can also be explained through neural connections and the imbalance or damage these can have.
• Serotonin is known to play a role in regulating mood, if a person has low levels of serotonin, the person can have low moods and other mental processes are often affected
• • Dopamine levels are thought to be abnormally high in people who suffer from OCD 
• Some forms of OCD have been linked with poor decision-making which could be down to abnormal functioning in the lateral parts of the frontal lobes. (the parts of the brain responsible for logical thinking and making decisions)
• Neural explanations PEEL 1:

  Strength - Antidepressants such as SSRIs, which are used to control levels of serotonin, are seen to be effective in reducing OCD symptoms - this supporting research suggests that biological factors may be responsible for OCD
• Neural explanations PEEL 2:

  Weakness - Not all OCD sufferers respond positively to antidepressants ( serotonin levellers), which would show it is not the neural network causing OCD in those patients - not a full explanation