Explaining ocd

• what does the biological explanation for OCD believe OCD is caused by?

  neural and genetic explanations
• outline the neUralic explanations for the biological explanation for OCD?

  The neural explanation proposes that when we encounter a worrying stimulus, our orbitofrontal cortex detects this and selects and appropriate action to respond with. It then sends signals to part of the brain which control movement e.g. motor cortex. The basal ganglia then monitors the outcome of the actions, and when a worrying stimulus has been dealt with it sends inhibitory serotonin into the synapse, inhibiting neural activity in the orbitofrontal cortex to stop the signals orignally sent to the Movement controllers
• what do biologists believe people with ocd have? (neural)

  They suggest that a patient with OCD will have an impaired connection between the basal ganglia and orbital frontal cortex, so the sent signals are much weaker than they should be meaning the orbitofrontal cortex is less inhibited than it should be and becomes hyperactive, generating the symptoms of OCD as the signals are continually sent in a loop.
• what are the strengths of neural explanations of OCD?

  supporting research, Max et al produced an MRI study on girls who had developed OCD after brain damage. they found she had damaged her basal ganglia supporting the idea of impaired communication being the cause of OCD. Saxena and Rauch in 2000 compared the brain activity of adults with and without OCD, concluding that brain activity was increased in the orbital frontal cortex of those withOCD than those without suggesting that the hyperactivity of the Brito frontal cortex may cause OCD. 
• outlie the genetic explanation for OCD?

  diathesis stress model - people have genetic vulnerabilities. Additionally, OCD is polygenetic meaning lots of genes are involved in its makeup, for examples the sert gene which produces reuptake proteins which carry seratonin back into the presynaptic terminal. There are two allleles of this, long and short. The long allele produces more reuptake proteins causing less serotonin to be available in the synaptic cleft and less inhibition in the orbitofrontal cortex therefore the symptoms of ocd are generated as the signals are continually sent in a loop.
• outline the strengths of the genetic explanations for OCD?

  research support :

  family studies

  twin studies
• elaborate on research support through family studies as a strength of genetic explanations for OCD?

  Lewis et als study which found that 37% of his OCD patients had parents with OCD and 21% had siblings with OCD suggesting that genetic makeup has at least small influential power on the explanations of OCD. 

  Nestadt found that people with a first-degree relative with OCD are more at risk of developing the disorder. 
• elaborate on twin studies as a strength of genetic explanations for ocd?

  Finally, Billet et al conducted twin studies and found that concordance rate for ocd was 68% for monozygotic twins and 31% for dizygotic twins, suggesting that OCD is partially inherited and therefore explained biologically.
• what are the weaknesses with the genetic explanations for OCD?

  family studies have criticisms as it is difficult to establish a cause and effect relationship when families share an environment, suggesting that external factors could also influence the development of OCD. 

  the concordance rate for MZ twins is never 100%, supporting the idea that environmental factors must also play a role in OCD.