biological approach to explaining OCD

• genetic explanation

  genes are involved in the individuals vulnerability to OCD - Lewis (1936) observed that of his OCD patients, 37% had parents with OCD and 21% had siblings with OCD suggesting it runs in families
• genetic explanations - candidate genes

  research has found that a specific gene could be responsible called candidate genes which involve regulating the production of serotonin but OCD may be polygenic meaning it is a combination of genes

  Taylor (2013) - analysed previous studies and found potentially 230 different genes may be linked to OCD, genes linked to serotonin and dopamine levels are though to have a role and are thought to be neurotransmitters linked to mood
• neural explanations

  the genes associated with OCD are likely to affect the levels of key neurotransmitters as well as structures in the brain
• neural explanations - the role of serotonin

  an explanation for OCD concerns the role of serotonin which is believed to help with mood regulation, neurotransmitters are responsible for relaying information from one neuron to another

  if a person has low levels of serotonin then the normal transition of mood relavent information does not take place therefore mood is affected
• neural explanations - decision making systems 


  some cases of OCD in particular hoarding disorder, seems to be associated with impaired decision making

  this is associated with abnormal functioning of the lateral (side parts) frontal lobes of the brain which are responsible for logical thought and making decisions
• genetic explanation evaluation strengths

  twin studies are an important way to study genetics, identical twins share all their genes and non-identical twins who are only as genetically similar as any siblings meaning that identical twins (MZ) are much more likely to share characteristics of OCD than non-identical twins (DZ)

  Nestadt (2010) found that 68% of MZ twins shared OCD as opposed to 31% of DZ twins
• genetic explanation evaluation limitations

  there are also environmental factors that can affect the risk of developing OCD, Cromer (2007) over half of the OCD clients experienced a traumatic event in their past,OCD was also more severe in those with one or more traumas suggesting genetic vulnerability is only a partial explanation for OCD
• neural explanations evaluation strengths

  drugs that act on serotonin are effective in treating OCD, suggesting that serotonin is involved in OCD
• neural explanation evaluation limitations

  depression is often co-morbid with OCD, the disruption of serotonin levels are also present in depressed people so we are not sure if the disruption is caused by OCD or depression