Biological approach to explaining OCD

Question 1

What 2 biological explanations are there for OCD

Answer 1

Genetic explanation

Neural explanation - e.g. neurotransmitters, brain structures

Question 2

What is genetic vulnerability

Answer 2

Relatives with disorders can increase the chance of an individual having the disorder, making them genetically vulnerable

Question 3

Outline Lewis’s study(genetic explanation)

Answer 3

Assessed OCD patients

Found that 37% had parents with OCD
21% had siblings with OCD

Shows that OCD runs in families due to genetic vulnerability

Question 4

What are candidate genes/state the 2 OCD candidate genes

Answer 4

Candidate genes - Genes that create vulnerability to disorders e.g. OCD

COMT gene - Regulates dopamine which controls movement/pleasure - gene causes high dopamine leading to e.g. constant compulsions

SERT gene - Regulates serotonin - gene causes low serotonin - can lead to e.g. depression, obsessive thoughts

Question 5

What does polygenic mean in terms of OCD

Answer 5

OCD is caused by several genes

E.g. COMT and SERT genes

Question 6

What does aetiologically heterogeneous mean in relation to OCD

Answer 6

Different groups of genes may cause OCD in different individuals

Question 7

How does abnormal levels of neurotransmitters cause OCD(neural explanation)

Answer 7

Dopamine and Serotonin

Dopamine responsible for pleasure, motor skills, reward

Serotonin responsible for mood, memory, sleep

Question 8

How does abnormal brain circuits/structure cause OCD(neural explanation)

Answer 8

1) Orbitofrontal cortex(OFC) sends signal to thalamus about worries
2) Caudate nucleus normally suppresses signals from OFC
3) If there’s damage to caudate nucleus, worries aren’t suppressed
4) Thalamus therefore altered leading to OCD

Question 9

Define the diathesis stress model in relation to OCD

Answer 9

Takes into account biological factors e.g. COMT gene, SERT gene etc and environmental factors such as stress, trauma which causes OCD when both are present.

Question 10

Evaluate the biological approach to explaining OCD

Answer 10

Strength - Research to support genetic vulnerability - Nestadt - Twin studies show 68% of identical twins share OCD compared to 31% non identical - counter - concordance rate not 100%/non identical share different environments

Strength - Real world application - e.g. low serotonin levels can be fixed via SSRI’s which increase serotonin in synapse which stimulate post neuron, benefits economy etc - counter - may not work for all people

Limitation - Cromer - Environmental factors involved - Half of OCD patients in sample had a traumatic experience - diathesis stress model

Reductionist approach