Biological approach to explaining OCD

What are the two explantations

Genetic and neural

Candidate genes

Researcher have identified specific genes which create a vulnerability to OCD

What genes are relevant

Serotonin genes

e.g. 5HT1-D beta, are implicated in the transmission of serotonin across synapses

Dopamine genes

e.g. implicated in OCD and may regulate mood

OCD is polygenic

Not caused by one single gene

Taylor found evidence that up to 230 different genes may be involved

Different types of OCD

One group of genes may cause OCD in one person but a different group maycause it in another - known as aetiologically heterogenous

Different types of OCD may be caused by different genetic variations

One strength is evidence for the genetic explanation

Nestadt et al. Reviewed twin studies and found 688% of identical twins shared OCD as opposed to 31% non identical

Marini and Stebnicki found that a person withas family member with OCD is 4 times as likely to develop it

This means genetically similar people are more likely to share OCD supporting the role of genetic vulnerability

one limitation is the existence of environmental factors

Genetic variation affects vulnerability but their are also environmental risk factors

Cromer et al. Found in one sample over half of people with OCD experienced a traumatic event

This means genetic vulnerability only provides a partial explanation from OCD

Low levels of serotonin

Lowers mood

Nerotrsnsmitters are responsible for relaying information from one neuron to another

Decision making systems in frontal lobes impaired

Some cases of OCD seem to be associated with impaired decision making

May be sociated with abnormal functioning of the lateral frontal lobes of the brain

Frontal lobes are responsible for logical thinking and making decisions

Parahippocampal gyrus dysfunctional

Associated with processing unpleasant emotions, functions abnormally in OCD

One strength of the neural model is supporting evidence

Antidepressants that work on serotonin reduced symptoms

Suggests serotonin is involved in OCD

OCD symptoms are part of conditions biological in origin e.g parkinson’s

This means biological factors are likely to be in involved in OCD

One limitation is there is no unique neural system

Many people with OCD also experience depression, this probably disrupts serotonin

Serotonin could be disrupted in many people with OCD because they are depressed as well

Serotonin may not be relvenat with OCD