Biological Explanations of OCD: Genetics

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Biological explanations have two major assumptions: 

• Individuals possess a genetic predisposition to develop anxiety that could take the form of OCD 
• Anxiety is caused by an abnormality within neurochemicals or actual structure of the brain.

Genetic research into the prevalence of OCD aims to isolate a familial genetic link that increases the tendency to develop OCD.  Research generally focusses on family and twin studies. 

First-degree relatives e.g. father, sister etc. share on average 50% of your genome. To investigate the genetic transmission of OCD, there is a comparison made between relatives of diagnosed cases of OCD and relatives of controls: 

• Pauls et al [1995] found a prevalence of up to 10% in first-degree relatives of those with OCD in comparison to only a 2% prevalence in the general population
• Nestadt et all [2000] 80 patients with OCD were compared with 73 patients without a mental illness and found that first-degree relatives of those with OCD had a risk of 11.7% of developing OCD at some point in their lives. Contrasting with that first degree relatives of patients without OCD only have a risk of 2.7% in the onset of OCD. 

Twin studies estalish genetic links…