the biological approach to explaining OCD

the biological approach to explaining OCD

1. genetic explanations

   • Lewis - OCD runs in families
     • 37% have parents with it
     • 21% have siblings with it
   • diathesis stress model
     • some people are more likely to suffer
       • may need an experience to trigger it
   • candidate genes
     • vulnerability for OCD
       • the gene 5HT1-D
         • responsible for the efficiency of transporting serotonin
   • OCD is polygenic
     • many genes involved
       • up to 230 genes may be involved
         • e.g. dopamine, serotonin, neurotransmitters
   • different types of OCD
     • the origin of OCD has different causes for each case

2. evaluation - genetic explanation

   • good supporting evidence
     • twin studies
       • Nestadt
         • 68% of identical twins
         • 31% of non identical twins
         • therefore genetic evidence
   • too many candidate genes
     • genetic explanations are unlikely to ever be useful
       • little predictive value
   • environmental risk hours
     • traumatic events can cause not just genes
       • Cromer found over half of patients had a traumatic event

3. neural explanations

   • the role of serotonin
     • neurotransmitters of serotonin
       • help regulate mood
       • neurotransmitters - rely information
       • low levels of serotonin
         • mood relevant info doesn't take place
           • can affect mental processes
   • decision making systems
     • abnormal functioning of the frontal lobes
       • these are responsible for logical thinking
     • abnormal functioning with the part that processes unpleasant emotions

4. evaluation - neural explanation

   • some supporting evidence
     • some antidepressants work purely on the serotonin system
       • therefore serotonin is involved in OCD
     • some OCD symptoms in Parkinson's disease
       • biological processes cause symptoms also responsible for OCD
   • not clear what neural mechanisms are involved
     • some studies found decision making systems are responsible
       • however no system has always been involved
   • we should not assume that neural mechanisms are involved
     • same neurotransmitters and structures function abnormally in OCD patients
       • but abnormal functioning does not cause OCD

5. evaluation +

   • the serotonin OCD link may be co - morbidity with depression
     • many people who have OCD also have depression
       • the depression probably involves disruption to the serotonin system
   • twin studies are flawed
     • twins grow up in the same environment
       • influences
     • may also experience different things
       • influences