The Biological Approach to explaining OCD

The biological approach to explaining Obsessive-Compulsive Disorder (OCD) focuses on physical processes in the body - especially genes and brain mechanisms. It is typically divided into genetic explanations and neural explanations.


Genetic explanations of OCD

Genetic explanations argue taht OCD is inherited through biological factors passed down from parents.

Key Ideas

  • OCD is considered polygenic, meaning it is influeenced by many genes, not a single “OCD gene”.

  • Different combinations of genes may increase vulnerability to OCD


Candidate genes:

Certain genes are linked to the regulation of Serotonin, a neurotransmitter involved in mood and anxiety.

For example:

  • The SERT gene affects serotonin transport

  • Variations in genes like COMT may influence dopamine levels


Supporting evidence:

Family studies show OCD is more common amond relatives

Twin studies:

  • Higher concordance rates in monozygotic (identical) twins that dizygotic twins suggest a genetic component


Evaluation:

+ Strong scientific support from twin studies

- Doesn’t fully explain OCD (concordance rates are not 100%)

- Enviromental factors (e.g. stress, learning) also play a role


Neural explanations of OCD

Neural explanations focus on brain structure and function, especially involving neurotransmitters and brain cirbuits.


  1. Neurotransmitters

Serotonin:

  • Low levels of Serotonin are linked to OCD

  • Serotonin helps regulate mood and anxiety

  • This explains why Selective Serotonin Reuptake Inhibitors (SSRIs) are effective treatments

Dopamine:

High levels of dopamine are also sometimes associated with OCD symptoms, especially repetative behaviours.


  1. Brain circuits (OCD loop)

Ocd is linked to abnormal acitivity in a brain circuit called the Orbitofrontal Cortex-basal ganglia loop.

Key brain areas:

Orbitofrontal Cortex (OFC): involved in decision-making and anxiety

Caudate Nucleus: normally suppresses inappropriate thoughts

Thalamus: relays signals

What goes wrong:

  • The caudate nucleus fails to filter worry signals

  • This leads to a hyperactive loop, causing persistent obsessive thoughts and compulsive behaviours


Evaluations (AO3 points)

Strengths:

  • Supported by brain imaging studies (e.g. PET scans show increased activity in OCD circuits)

  • Practical application: led to effective treatments like SSRIs

Limitations:

  • Cause vs effect problem (prain differences may result from OCD, not cause it)

  • Oversimplifies OCD - doesn’t explain individual experiences or triggers

  • Reductionist: ignores psychological and enviromental influences


Summary:

Genetic explanations: OCD is inherited through multiple genes affecting neurotransmitters

Neural explanations: OCD involves abnormal brain circuits and neurotransmitter imbalances

Best understanding comes from an interactionist approach (biology + evniroment)