The biological approach to explaining OCD

What is the emphasis of the biological approach on?

How the physical elements of our body may be used to understand behaviour.

What three factors does the biological approach look at?

Genes

The brain

Neurotransmitters in the brain

GENETICS: What are genes?

Things present in every cell of the body that provide instructions for physical and psychological characteristics.

Genetic explanations: How does inheritance work, in terms of mental disorders?

Individuals inherit specific genes from their parents.

These are related to the onset of OCD.

What are the two possible genes that cause OCD?

The COMT gene

The SERT gene

What does the COMT gene stand for?

This gene is involved in the production of catechol-O-methyltransferase, or COMT for short.

What is the function of the COMT gene?

COMT regulates the production of neurotransmitter dopamine. This has been implicated in OCD.

Why is the COMT gene associated with OCD?

One form of the COMT gene has been found to be more common in OCD patients than people without the disorder.

What is the function of the SERT gene?

It affects the transport of neurotransmitter serotonin, creating lower levels of this.

Why is the SERT gene associated with OCD?

Lower levels of serotonin are implicated in OCD.

What’s the explanation for how these genes may lead to OCD?

Diathesis-stress.

Explain diathesis-stress.

Each individual gene only creates a vulnerability - diathesis - for conditions such as OCD.

Other factors - stressors - affect if any mental condition develops, and if so which one.

So some people could possess the COMT or SERT gene variations but suffer no ill effects.

NEURAL EXPLANATION: What is the definition of neural?

Concerning the brain

What are the two neural explanations for OCD?

Abnormal levels of neurotransmitters

Abnormal brain circuits

What two neurotransmitters are usually abnormal in people with OCD?

Dopamine and seretonin

How are dopamine levels abnormal in people with OCD?

Dopamine levels are thought to be abnormally high.

How are seretonin levels abnormal in people with OCD?

Serotonin levels are lower.

What area of the brain is thought to be abnormal in people with OCD?

Several areas of the frontal lobes.

Explain how a normal brain circuit suppresses worries.

The caudate nucleus (located in the basal ganglia) normally suppresses signals from the orbifrontal cortex (OFC).

In turn, the OFC sends signals to the thalamus about things that are worrying.

Explain an OCD patient’s brain circuit - ‘worry circuit’

The caudate nucleus is damaged, and it fails to suppress minor ‘worry’ signals.

This alerts the thalamus, which in turn sends signals back to the OFC.

This acts as a worry circuit.

Why is dopamine linked to these systems?

It’s the main neurotransmitter of the basal ganglia.

High levels of dopamine lead to overactivity of this region.

Why is serotonin linked to these systems?

Serotonin plays a key role in the operation of the OFC and caudate nuclei.

Therefore, abnormal levels of serotonin may cause these areas to malfunction.

Positive eval

Research support for genetic basis of OCD - family studies. Nestadt (2000) found that people with a first-degree relative with OCD had a five-times greater risk of having OCD than the general population.

Research support for neural basis of OCD - Pigott (1990) found that antidepressant drugs that increase seretonin activity reduce OCD symptoms. This proves that low levels of the neurotransmitter cause OCD.

Negative eval

The biological approach is reductionist - ignores psychological explanations such as the two process model. This can be a cause for OCD - associating neutral stimulus with anxiety.

Not all OCD sufferers respond positively to SSRIs - proves that the cause of OCD isn’t solely neural.