PATH 11 - OCD explanations 2 Flashcards
(11 cards)
What is the biological approach?
A perspective that emphasises the importance of physical processes in the body such as genetic inheritance and neural function
What is the genetic explanation for OCD?
- Genes make up chromosomes and consist of DNA which codes the physical features of an organism (such as eye colour, height) and psychological features (such as mental disorder, intelligence)
- Genes are transmitted from parents to offspring, i.e. inherited
What are candidate genes?
- Specific genes are likely to be involved in vulnerability for OCD e.g. 5HT1-D beta, coding for serotonin
- Some of these genes are involved in regulating the development. 230 different candidate genes have been identified
What does polygenic mean in terms of OCD?
OCD is polygenic in the sense that OCD is not caused by one single gene but by a combination of genetic variations that together significantly increase vulnerability
What does aetiologically heterogenous mean in terms of OCD?
Meaning the origins (aetiology) of OCD vary from one person to another (heterogeneous) e.g. one group of genes may cause OCD in one person, but a different group of genes may cause the disorder in another person
Who conducted the study on OCD being genetic?
Aubrey Lewis
Outline the study conducted by Lewis on the genetic explanation of OCD?
- Genes are involved in individual vulnerability to OCD
- In a classic study, Aubrey Lewis (1936) observed that of his OCD patients, 37% had parents with OCD and 21% had siblings with OCD
- This suggests that OCD runs in families, although what is probably passed on from one generation to the next is genetic vulnerability not the certainty of OCD
- According to the diathesis-stress model certain genes leave some people more likely to develop a mental disorder but it is not certain
- Some environmental stress (experience) is necessary to trigger the condition
What are the strengths of the genetic explanation?
Research support
What research support is there for the genetic explanation of OCD?
- One strength of the genetic explanation for OCD is the strong evidence base
- There is evidence from a variety of sources which strongly suggests that some people are vulnerable to OCD as a result of their genetic make-up
- One source of evidence is twin studies
- In one study Gerald Nestadt et al. (2010) reviewed twin studies and found that 68% of identical twins (MZ) shared OCD as opposed to 31% of non-identical (DZ) twins
- Another source of evidence for a genetic influence on OCD is family studies
- Research has found that a person with a family member diagnosed with OCD is around four times as likely to develop it as someone without (Marini and Stebnicki 2012)
- These research studies suggest that there must be some genetic influence on the development of OCD
What are the limitations of the genetic explanation of OCD?
Environmental risk factors
What are the environmental risk factors of the genetic explanation of OCD?
- One limitation of the genetic model of OCD is that there are also environmental risk factors
- There is strong evidence for the idea that genetic variation can make a person more or less vulnerable to OCD
- However, OCD does not appear to be entirely genetic in origin and it seems that environmental risk factors can also trigger or increase the risk of developing OCD
- In one study for example, Kiara Cromer et al. (2007) found that over half the OCD clients in their sample had experienced a traumatic event in their past
- OCD was also more severe in those with one or more traumas
- This means that genetic vulnerability only provides a partial explanation for OCD
