ocd

• genetic explanation


  suggests that the onset of OCD is a result of our genetic makeup that we are born with
• twin/family studies


  Lewis (1936) found 37% had parents with OCD and 21% had siblings with OCD

  Miguel et al (2005) used monozygotic (identical) twins and dizygotic (non-identical) twins. they found that 53%-87% chance of one MZ twin developing OCD if one already had it compared to a 22%-47% change in DZ - shows that OCD has a genetic basis but not a 100% concordance rate so other factors e.g environmental (impact)
• COMT gene


  this gene is involved in the production of the neurotransmitter dopamine. Take et al (2013) found one form of the COMT gene to be more common in OCD patients. This variation produced lower activity of the COMT gene and higher levels of dopamine
• SERT gene 


  AKA: 5-HTT as it affects the transmission of serotonin leading to lower levels in the brain. Bengal et al (1999) compare 75 caucasian patients with OCD to 397 ethnically matched individuals who did not have OCD. it was found the patients with OCD were more likely (47%) to carry two copies of the long allele of the 5-HTT gene compared to controls (32%)
• epigenetic

  although we are born with our DNA that does not change, the way our cells and genes are activated in what can lead to changes in mental illness. these outside factors can affect the way the gene 'expresses' itself.
• Neural explanations


  Focus on what is happening in the brain
• Neurotransmitters


  Pass information (messages) from one neuron to another
• Serotonin


  Brain chemical that regulates mood, anxiety, memory and sleep
• Dopamine


  Brain chemical linked to experiencing motivation, rewards and compulsions
• Increased dopamine leads to feelings of pleasure, but with OCD the anxiety associated with obsessive thinking is stopped only by the pleasure of completing the compulsion
• Orbitofrontal cortex (OFC)


  • Sends signals to the thalamus about things that are worrying
  • If a part of the basal ganglia is damaged, the OFC signal is not stopped and the thalamus is alerted
• OCD brain circuit


  1. Impulse brought to attention

  2. Behaviour performed to address impulse

  3. Difficulty stopping/ignoring impulses from this circuit
• PET scans show heightened activity in the OFC when OCD sufferers have active symptoms
• strengths of the biological approach to explaining OCD

  • supportive research (nestadt et al, saxena and Rach)
  • practical application
• nestadt et al


  reviewed twin studies and found that 68% of identical twins shared OCD and 31% of non-identical twins
• saxena and rach


  reviewed studies of OCD that used PET,fMRI and MRI neuro imaging techniques and found consistent evidence of an association between the OFC and OCD symptoms
• limitations of the biological approach to explaining OCD

  • relationship between biology and OCD is not clear cut
  • the research is correlational
  • lack of precision
  • reductionist
• SSRIs


  selective serotonin reuptake inhibitors
• how do SSRIs work

  • the presynaptic cell sends information via a synapse
  • by sending this information, neurotransmitters are released into the gap
  • the receptors on the surface of the postsynaptic cell recognises these neurotransmitters and passes on the 'message'
  • 90% of these neurotransmitters are released from the receiving receptors and taken up again by the sending cells
  • SSRIs to the reuptake of serotonin meaning it stays in the synapse for longer than it normally would
  • this can lead to repeated stimulation of the receptors on the post synaptic nerve ending and higher levels of serotonin
• strengths of the biological approach for treating OCD

  • supportive research (soomro et al)
  • quick and easy to administer
• soomro et al


  reviewed studies comparing SSRIs to placebos and all 17 studies showed better results for SSRIs and that they are most effective when combined with a psychological treatment (e.g CBT)
• limitations of the biological approach for treating OCD

  • issue of what happens when people stop taking the drug (Simpson et al)
  • side effects to drugs (indigestion, blurred vision, weight gain)
• simpson et al


  suggests that 45% of patients treated with medication relapsed within 12 weeks compared to 12% who had received a psychological treatment