biological approach- explaining OCD

genetic explanations

genes are transmitted from parents to offspring

OCD may be inherited from parents through DNA

genetic vulnerability

Lewis observed his OCD patients and found that 37% has parents with OCD and 21% had siblings with OCD

this suggests that OCD runs in families, and genetic vulnerability may be passed on through generations

diathesis-stress model= suggests that certain genes leave some people more likely to develop a mental disorder

candidate gene

these genes create vulnerability to OCD

e.g. 5HT1-D beta which is implicated in the transportation of serotonin across synapse

polygenic

OCD is not caused by one gene

230 genetic variations may be involved in OCD

different types of OCD

aetiologically heterogeous= different groups of genes may cause OCD in different people

some evidence suggest that different types of OCD (hoarding, religious obsession) may be a result of particular genetic variations

neural explanations

physical and psychological characteristics are determined by the behaviours of the nervous system (e.g. the brain)

abnormally functioning neurotransmitters or brain structures may be the cause of OCD

role of serotonin

if a person has low levels of serotonin then normal transmission of mood related information doesn‘t take place and the person may experience low mood

decision making systems

some cases of OCD may be associated with impaired decision making, which may be to do with abnormal functioning of the sides of the frontal lobe (responsible for logical thinking)

evaluation strength- research support for genetic explanation

twin studies= 68% of identical twins (MZ) shared OCD as opposed to 31% of non identical twins

other research has found that a person with a family member diagnosed with OCD is 4 times more likely to develop it

shows some genetic influence

evaluation weakness- ignores environmental risk factors

many individuals with OCD have also experienced a traumatic life event

research has shown that OCD was more severe in people who had experienced one or more traumatic life event

genetic vulnerability is only a partial explanation

evaluation strength- research support for neural explanation

antidepressants that work purely on serotonin are effective in reducing OCD symptoms, suggesting serotonin may be involved in OCD

evaluation weakness- no unique neural system

many people with OCD also experience clinical depression. depression probably involves disruption to the action of serotonin, challenges the link between serotonin and OCD