biological approach to explaining OCD: genetic explanations

Question 1

what is the biological approach?

Answer 1

• a perspective that emphasises the important of physical processes in the body such as genetic inheritance and neural functioning
• OCD is a good example of a condition that may largely be understood as biological in nature

Question 2

what are genes involved in?

Answer 2

indiviual vulnerability to OCD

Question 3

what did lewis (1936) observe?

Answer 3

• that of his OCD patients, 37% had parents with OCD and 21% had siblings with oCD
• this suggests that OCD runs in families

Question 4

what is probably passed on form one generation to the next?

Answer 4

genetic vulnerability, not the certainty of OCD

Question 5

what does the diathesis-stress model suggest?

Answer 5

• certain genes leave some people more likely to develop a mental disorder but it is not certain
• some environmental stress is necessary to trigger the condition

Question 6

what are candidate genes?

Answer 6

• genes with create vulnerability for OCD
• some of these gens are involved in regulating the development of the serotonin system
• eg. the gene 5HT1-D beta is implicated in the transport of serotonin across synapses

Question 7

what are some possible candidate genes?

Answer 7

• SERT: involved in regulating serotonin
• COMT: regulates the production of dopamine (dopamine affects motivation and drive)

Question 8

what does polygenic mean?

Answer 8

• like many conditions, OCD seems to be polygenic
• this means that OCD is not caused by one single gene but by a combination of genetic variations that together significantly increase vulnerability

Question 9

what did steven taylor (2013) find?

Answer 9

he analysed findings of previous studies and found evidence that up to 230 different genes may be involved in OCD

Question 10

what kind of genes have been studied in relation to OCD?

Answer 10

• those associated with the action of dopamine and serotonin
• these neurotransmitters are believed to have a role in regulating mood

Question 11

what does aetiologically heterogenous mean?

Answer 11

• the origins of OCD vary from one person to another
• one group of genes may cause OCD in one person but a different group of genes may cause the disorder in another person

Question 12

what might different types of OCD be caused by?

Answer 12

there is also some evidence to suggest that different types of OCD may be the result of particular genetic variations, such as hoarding disorder and religious obsession

Question 13

what did bellodi et al. (2001) find?

Answer 13

• they claimed that genetic factors play a role in the disorder
• using evidence from twin studies and family studies, they showed that close relatives are more likely to have the disorder than more distant relatives

Question 14

what did pauls et al. (1995) find?

Answer 14

higher morbid risks of OCD in first-degree relatives of of OCD probands vs. controls (10% vs. 1.9%)

Question 15

evaluation: research support - nestadt et al. (2010)

Answer 15

reviewed twin studies and found that 68% of MZ twins shared OCD as opposed to 31% of DZ twins

Question 16

evaluation: research support - marini and stebnicki (2012)

Answer 16

a person with a family member diagnosed with OCD is around 4 times as likely to develop it as someone without

Question 17

evaluation: environmental risk factors

Answer 17

• 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
• cromer et al. (2007) found that over half of 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

Question 18

evaluation: animal studies

Answer 18

• evidence from animals studies showing that particular genes are associated with repetitive behaviours in other species eg. mice ahmari (2016)
• however, although mice and humans share most genes, the human mind and brain are much more complex, and it may not be possible to generalise from animal repetitive behaviour to human OCD