OCD: Biological explanations

Question 1

Brain structure

Answer 1

• orbitofrontal cortex (OFC) and thalamus involved in OCD
• thalamus: cleaning, checking, and other safety behaviours
• OFC: decision making, worrying abt behaviour

Question 2

neural explanations

Answer 2

• OFC and thalamus overactive
• increased: cleaning, checking safety, and anxiety

Question 3

Worry circuit

Answer 3

1) OFC identifies worry
2) Caudate nucleus: damaged, fails to filter minor worry signals
3) Thalamus: transfers minor and major worries from CN to OFC
4) obsess over minor worries, act in ways disproportionate to the worry

Question 4

neurotransmitters

Answer 4

• too much dopamine - increases level of activity leading to compulsive behaviours
• not enough serotonin in same parts so dopamine not controlled, anxiety increased
• abnormal serotonin affects OFC and CN function

Question 5

genetic explanations

Answer 5

• OCD polygenic
• Taylor (2013) found 230 candidate genes

Question 6

twin studies

Answer 6

• conducted by Nestadt
• MZ - 68%
• DZ - 31%

Question 7

genes linked to OCD

Answer 7

• COMT gene: variation causes decreased control of dopamine
• SERT gene: variation affects transport of serotonin

Question 8

diathesis-stress

Answer 8

people gain vulnerability to OCD through genes, but trigger by an environmental stressor e.g. bereavement

Question 9

neural explanation strengths

Answer 9

• research support (brain scan shows association between brain scan evidence and OFC and OCD symptoms
• useful apps (SSRIs found to be effective)

Question 10

genetic explanation strengths

Answer 10

• research support from twin studies( 68% in mz 31% in dz)

Question 11

biological approach limitations

Answer 11

• reductionist (only focuses on physiological processes)

Question 12

drug therapy strengths

Answer 12

research support-ssris more effective than placebos
- easier and more cost effective

Question 13

drug therapy limitations

Answer 13

• not long term
• lots of side effects