Biological approach to OCD

Question 1

What does the biological explanation of OCD say ?

Answer 1

• says the disorder is caused by faulty biological processes

Question 2

What are the two types of neurotransmitter called ?

Answer 2

• serotonin
• dopamine

Question 3

What is serotonin ?

Answer 3

• mood transmitter
• contributes to well-being and happiness
• helps sleep cycle
• Affected by exercise and light exposure

Question 4

What is Dopamine ?

Answer 4

• pleasure transmitter
• feelings of pressure, addiction, movement and motivation
• people repeat behaviours that lead to a relapse

Question 5

What is the neural explanation (the worry circuit) ?

Answer 5

• orbital frontal cortex (OFC) sends signals yo the thalamus about worrying
• These signals go through the caudate nucleus
• Thalamus returns signals to the worry circuit
• Serotonin is needed for the caudate nucleus to block minor worry signals from the OFC to the thalamus

Question 6

What is the genetic explanation for OCD ?

Answer 6

• 2-3% pf the population have OCD
• Lewis - of his patients, 37% of their parents and 21% of their siblings have it
• Nestadt et al - 5 times a greater risk of OCD if a first degree relative has OCD

Question 7

What is a candidate gene ?

Answer 7

A gene that creates a genetic vulnerability for a disorder

Question 8

What are the OCD candidate genes ?

Answer 8

COMPT = transmission of dopamine
SERT = transmission of serotonin
5HT1-D-beta = transmission of serotonin across a synapse

Question 9

What does polygenic mean ?

Answer 9

Disorders that are caused by the involvement of multiple genes

Question 10

What was Taylor’s study ?

Answer 10

Evidence suggested that there are 230 different genes involved in OCD

Question 11

What is diathesis-stress ?

Answer 11

The model suggests that genetics give a person a genetic vulnerability to OCD but it may be triggered by environmental stimuli.
1. Diathesis = vulnerability
2. Stress - trigger
3. OCD

Question 12

What are the evaluations of the genetic explanation ?

Answer 12

Strength = Strong evidence base
-Evidence has suggested that people are vulnerable to OCD due to their genetic makeup.
- Nestadt et al - reviewed twin studies and found 68% of identical twins shared OCD as opposed to 31% non-identical twins

Limitation = Environmental risk factors
- OCD doesn’t seem to be entirely genetic in origin
- Environmental risk factors can trigger the development of OCD
- Cromer = found half of their patients with OCD had experienced a traumatic life experience

Question 13

What are the evaluations of the neural explanation ?

Answer 13

Strength = supporting evidence
Antidepressants that work on just serotonin are effective in reducing symptoms
This shows that serotonin may be involved in affecting OCD

Limitation = The link between serotonin and OCD may be not just be unique to OCD
- Many people with OCD also experience clinical depression (Co-morbidity)
- This depression creates a disruption to the serotonin neurotransmitters
- Serotonin activity is disrupted as many with OCD also have depression
- Shows serotonin may not be just linked to OCD symptoms (e.g depression