Biological Approach - Explaning OCD

Question 1

Which mutations may lead to symptoms of OCD?

Answer 1

• Mutation in COMT gene causes low levels of COMT enzyme so less dopamine is broken down. High levels of dopamine maintain interest and motivation (compulsions)
• Mutation in SERT gene causes low levels of serotonin transporter protein so more serotonin removed. Low levels of serotonin mean the brain doesn’t communicate information about mood effectively

Question 2

Diathesis-stress model

Answer 2

Certain genes may lead people more likely to suffer OCD but environmental stress may trigger it

Question 3

Ventral motivational CSTC circuit

Answer 3

OFC sends worry signals to basal ganglia. Basal ganglia is hyperactive so minor worries not filtered out reach thalamus, pass back to OFC, forming recurring obsessive thought loop. Compulsions attempt to break loop

Question 4

Parahippocampal gyrus

Answer 4

Processes unpleasant emotions

Question 5

Strengths of the biological approach to explaining OCD

Answer 5

• Higher concordance rates for MZ twins (eg. Nestadt found 68% concordance in MZ, 31% in DZ twins, suggesting genetic vulnerability to OCD)
• Empirical evidence for role of OFC (eg. PET scanners show hyperactivity in the OFC, supporting worry circuit)

Question 6

Limitations of the biological approach to explaining OCD

Answer 6

• Ignores role of environmental factors (eg. Cromer found over half of OCD patients had experienced a traumatic event, suggesting diathesis-stress model)
• Credible alternative explanations (eg. Behavioural treatments for OCD improved symptoms for 75% adults, suggesting two-process model)