biological approach to explaining OCD - genetic

what is genetic vulnerability?

the idea that certain genes make us more vulnerable to certain disorders/conditions

what did researchers find about genetic vulnerability in relation to OCD?

37% of OCD patients had parents with OCD and 21% had siblings with OCD

• suggests OCD runs in families

what are candidate genes?

genes that cause vulnerability to a disorder/condititon

OCD is …, therefore … genes influence it

polygenic, multiple

what did researchers find about candidate genes in relation to OCD?

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

what candidate gene affects dopamine levels?

SLC6A3

what does aetiologically heterogeneous mean?

a disorder/condition has multiple factors that cause it

what is the purpose of twin studies?

to determine/test genetic vulnerability

what did researchers find from twin studies on OCD?

68% of monozygotic/identical twins shared OCD, compared to 31% of dizygotic/non-identical twins

what is the diathesis-stress model?

the explanation that a disorder is the result of an interaction between genetic predisposition vulnerability and stress, usually caused by life events and factors

• suggests that a person with a greater genetic vulnerability is more likely to develop a mental illness when exposed to stressors, as the stress can trigger the underlying predisposition

what is the strength of the genetic explanation?

good supporting evidence:

• research on genetic vulnerability 

• research on candidate genes

• twin studies

what are the weaknesses of the genetic explanation?

• too many candidate genes

• environmental factors

too many candidate genes

• hard to determine all the genes involved in influencing OCD

• several genes involved and each only increases the risk of OCD by a small amount

• genetic explanation provides little predictive value - the likelihood that a test correctly indicates the presence or absence of a condition

• therefore decreases validity

study on genetic vulnerability has low temporal validity

• study was conducted in 1936

• high chance that there has been in increase in the percentage of population that carry candidate genes due to natural selection

• sufferers of OCD tend to be hypervigilant, which may be helpful in being aware in dangerous situations

• therefore proportion of parents and siblings of OCD sufferers that also have OCD will have varied in past 90 years