(9) Biological approach to explaining OCD

Genetic Explanations: What are the genes involved?

OCD is a disorder that is polygenic; there are many different genes involved. Two of the most important genes is the SERT gene and the COMT gene.

Genetic Explanations: SERT Gene:

people with this gene in high function do not have enough serotonin at the synapse. (Low levels of serotonin are implicated with OCD - anxiety).

Genetic Explanations: COMT Gene:

people with this gene in low function have too much dopamine at the synapse (high levels of dopamine are implicated with OCD - compulsion control/threat perception).

Genetic Explanations: Diathesis- stress model:

the role of the environment in the triggering of genes into their vulnerable states (e.g. high or low function, if they have a predisposition). Usually through stress or trauma.

Neural explanations: What is the neural explanation

assumes that neurotransmitters play a role in the development of the disorder

Neural explanations: role of serotonin and dopamine in OCD

• low levels of serotonin causes anxiety which causes obsessional thoughts

• high levels of dopamine causes compulsive behaviours being excessively rewarding

Neural Explanations: The Worry Circuit

PET scans indicate high activity in the Orbital Frontal Cortex (OFC) in patients with OCD; a brain area associated with conversion of sensory information into thoughts (e.g. hazard perception). E.g. seeing a dirty desk/door handle/strange smell…

The Caudate Nucleus should suppress signals from the OFC, (e.g. worry about potential germ hazard). If the Caudate Nucleus is damaged, these worry signals cannot be suppressed, and a minor hazard can be misperceived as a major hazard (e.g. dirt and germs causing major harm/death).

AO3: Biological Explanation of OCD: supporting research

Nestadt (2010) reviewed twin studies of OCD and found that 68% of identical twins (MZ) shared OCD as opposed to 31% of non-identical twins (DZ) showing a genetic predisposition.

This adds validity to the biological approach to explaining OCD (via genetics).

AO3: Biological Explanation of OCD: serotonin link to OCD

Many people who suffer from OCD also suffer from low mood (depression?). This leaves us with a problem when it comes to using serotonin as a CAUSE of OCD, as it could simply be that the serotonin system is disrupted in many patients with OCD because they are suffering from depression AS WELL AS OCD.

This means that serotonin may not be implicated in OCD specifically.

This limits the usefulness of the serotonin explanation, as cause and effect is unclear.

AO3: Biological Explanation of OCD: Nature/ nurture

Mostly a nature explanation as it uses genetics and biological structures as the key reason for the reason for OCD. But also there is an interactionist stance with nurture in the diathesis stress model increasing validity