biological approach to explaining OCD

overview of this topic

The biological approach explains OCD in terms of genetic vulnerability and neural (brain and neurotransmitter) functioning. OCD is considered to have a strong biological basis compared to some other mental disorders.

AO1 genetic vulnerability

• OCD has a strong biological component and can be explained genetically.

• Genes increase a person’s vulnerability to OCD rather than causing it directly.

• Lewis (1936) found:

  • 37% of OCD patients had parents with OCD

  • 21% had siblings with OCD

• This suggests OCD runs in families.

what is the diathesis-stress model

• According to the diathesis–stress model, genes create a predisposition to OCD.

• OCD only develops if this genetic vulnerability is triggered by environmental stress.

• This explains why not everyone with genetic risk develops OCD.

what are candidate genes

• Candidate genes are genes that increase vulnerability to OCD.

• Many candidate genes are involved in the serotonin system, which regulates mood.

• The 5HT1-D beta gene affects the transport of serotonin across synapses.

• Disruption to serotonin transmission may contribute to OCD symptoms.

explain meaning of OCD is polygenic

• OCD is polygenic, meaning it is caused by many genes, not a single gene.

• Taylor (2013) found evidence that up to 230 genes may be involved.

• These genes are linked to the functioning of:

  • Serotonin

  • Dopamine

• Both neurotransmitters are involved in mood regulation.

explain the different types of OCD

• OCD is aetiologically heterogeneous, meaning it has different genetic causes.

• Different combinations of genes may cause OCD in different individuals.

• Certain genetic variations may be linked to specific OCD subtypes, such as:

  • Hoarding disorder

  • Religious obsession

what is the role of neurotransmitters

• Genes linked to OCD affect levels of key neurotransmitters.

• Neurotransmitters are chemical messengers that transmit signals between neurons.

what is the role of serotonin

• Serotonin is a neurotransmitter involved in regulating mood.

• Low levels of serotonin disrupt normal transmission of mood-relevant information.

• Reduced serotonin functioning may result in obsessive thoughts and compulsive behaviour.

• Some cases of OCD are explained by reduced activity in the serotonin system.

what is the decision making system

frontal lobe

explain frontal lobe as decision making system

• Some forms of OCD, particularly hoarding disorder, are linked to impaired decision-making.

• This is associated with abnormal functioning of the lateral frontal lobes.

• The frontal lobes are responsible for logical thinking and decision-making.

what are the evaluation points for genetic explanations

1. evidence of being vulnerable to OCD due to genetic makeup

2. evidence to show OCD is genetic

3. do not funny understand

what are the evaluation points for neural explanations

1. evidence to support

2. symptom or cause?

evaluation - genetic - evidence

P: there is evidence from a variety of sources for the idea that some people are vulnerable to OCD as a result of their genetic make up

E: one of the best sources of evidence for the importance of genes is twin studies

E: Nestadt reviewed previous twin studies and found that 68% of identical twins shared OCD as opposed to 31% of non-identical twin twins

L: they strongly suggest a genetic influence on OCD

evaluation - genetic - dont fully understand

P: although twins study strongly suggest that OCD is under genetic influence psychologists have been much less successful at pinning down all the genes that are involved

E: one reason for this is that it appears that several genes are involved and that each genetic variation only increases the risk of development of OCD by a fraction

L: we cannot claim to fully understand the neural mechanisms involved in OCD

evaluation - neural - evidence

P: there is evidence to support the role of some neural mechanisms in OCD

E: for example, some antidepressants work purely on the serotonin system in increasing level levels of the neurotransmitter

E: such drugs are effective in reducing OCD symptoms and this suggests that serotonin system is involved in OCD

L: also OCD symptoms form part of a number of other condition conditions that are biological and origin (for example Parkinson's) which further supports the use of biological treatments

evaluation - nerual - pass through families

P: OCD is passed through families through genetics

E: Lewis examined patients with OCD and found that 37% of patients with OCD had parents with the disorder

E: also found 21% had siblings which suffered

L: evidence to show OCD is genetic

evaluation- neural - cause or effect

P: there is evidence to suggest that various neurotransmitters and structures of the brain do not function normally in patients with OCD

E: however, this is not the same as saying the abnormal functioning causes OCD

L: these biological abnormalities could be a result of OCD rather than it's cause