OCD

Question 1

What did Lewis et al find?

Answer 1

Lewis et al. found that of his OCD
patients, 37% had parents with OCD and 21% had siblings with OCD.

Question 2

How many genes are involved in OCDs developement

Answer 2

OCD is polygenic, meaning
that up to 230 different genes are involved in its development

Question 3

What is one candidate gene for developing OCD

Answer 3

5HT1-D beta, which is implicated in the
efficiency of serotonin transport across synapses

Question 4

Evaluate biological explaination

Answer 4

+ = Supporting evidence:
Nestadt et al. reviewed previous twin studies of OCD and found that
68% of identical twins, compared to 31% of non-identical twins, share OCD.
T: Credible theory
CC: This genetic vulnerability must be paired with an environmental stressor to result in
OCD

— = Too many candidate genes: over 230 candidate genes each individually coding for an
increased risk of OCD
T: Low practical value as its hard to apply drugs

• Ignores environmental factors: Cromer et al. found that of his OCD patients, over half had
  experienced a trauma in their lives
  T: Not credible theory