Genetic

• What is the strength of the biological examination of OCD?


  Research support seen in family studies
• Who was the psychologist who researched this?

  Lewis
• What year did he research this in?

  1936
• What did he find?

  He examined patients with OCD and found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered from the disorder.
• What did Nestadt et al find?


  In 2000, they took this point further and proposed that individuals who have a first degree relative with OCD, they are up to five times more likely to develop the disorder over their lifetime compared to members of the general population without this genetic link.
• What is the impact of this point?

  Research from family studies like this provides support for a genetic explanation of OCD, although it does not rule out other(environmental) factors playing a role.
• What is a weakness of the biological explanation to OCD?


  Too many candidate genes
• Psychologists haven't been able to pin down ALL the genes.
• One reason for this is that several genes are involved and that each genetic variation only increases the chance of OCD by a fraction.
• This suggests that the genetic explanation isn't very useful as it doesn't allow us to predict how/when OCD will develop in patients- has the issue of predictive validity.
• What is a different weakness for the biological explanation to OCD?

  Diathesis-stress model is more likely.
• Who was the psychologist who found this?

  Cromer et al(2007)
• What did they find?

  In over half of their sample, the patients had suffered from a traumatic event in their past, and that OCD was most severe if they had suffered more than one trauma.
• What does the diathesis model suggest?


  The diathesis model suggests that a person's genes make them more SUSCEPTIBLE to a disorder.

  E.G. If a parent suffers from OCD, it doesn't DEFINTELY mean the child will suffer; it means they are more vulnerable to the disorder(genotype) and it may be more likely to be triggered than a child without an OCD parent.
• What is the impact of this?

  This suggests that genes cannot be the ONLY cause of OCD. It may play a role but environmental factors are key in triggering it.
• The biological explanation does not account for environmental influences.
• The biological approach supports the nature debate in Psychology.
• The biological approach ignores the nurture debate.
• Nestadt et al (2010) found that 68% of identical twins and 31% of non-identical twins experience OCD, which suggests a very strong genetic component.
• The biological explanation for OCD is very reductionist.
• The biological approach does not take into account cognitions and learning.
• Samuels et al (2007) found a genetic link in hoarding behaviour in OCD patients.
• Twin studies can be criticised as nature and nurture are difficult to separate.
• There is much science to support the idea for the genetic explanation of OCD and it has practical application in identifying the potential for genetic vulnerability in families.
• Research from family studies suggests that there is a genetic component to OCD, as individuals with a family history of the disorder are more likely to develop OCD themselves.
• According to Pauls (2010) approximately 25-40% of patients with OCD have parents with the disorder.
• Genetic vulnerability is believed to only be half of the cause. The diathesis-stress model, includes external influences in the cause of disorders.
• The diathesis-stress model suggests that people have a biological predisposition which is triggered by an external environmental stressor, causing disorders.
• Ahmari (2016) used animal studies to show particular genes are involved in repetitive behaviour in rats.
• Animal studies like Ahmari (2016) cannot be generalised to humans.
• Van Grootheest et al (2005) conducted a meta-analysis of 28 twin studies and found support for the genetic explanation of OCD.
• Van Grootheest et al (2005) found genetic influences ranged from 45% to 65% in children and 27% to 47% in adults.
• The biological explanation for OCD is very reductionist.
• The biological approach does not take into account cognitions and learning.
• Some psychologists suggest that OCD may be learnt through classical conditioning and maintained through operant conditioning.
• Identical twins (MZ) provide strong support for the genetic explanation of behaviour.
• Cromer et al (2007) found that over half the OCD patients in their study experienced a traumatic event, supporting the nurture side of the debate.
• Support for the biological explanation of OCD comes from twin studies.
• Nestadt et al (2010) conducted a review of previous twin studies examining OCD.
• The biological approach ignores the nurture debate.