In Nestadt et al.'s family study of OCD, first-degree relatives of OCD sufferers had approximately what increased risk compared to relatives of healthy controls?

• A. 11.7% vs 2.7%
• B. 20% vs 5%
• C. 50% vs 25%
• D. 2% vs 0.5%

Answer: (A)

OCD shows familial clustering, meaning relatives of someone with the disorder are more likely to develop it than relatives of someone without OCD. Nestadt and colleagues tested this by comparing first-degree relatives of OCD patients with relatives of healthy controls and looked at lifetime prevalence. They found about 11.7% of first-degree relatives of OCD patients have OCD, versus about 2.7% among relatives of controls. This reflects roughly a fourfold increase in risk for close relatives, illustrating a meaningful genetic or familial contribution to OCD. The figure aligns with the general population baseline (around 2–3%), so the jump to about 11.7% in relatives of affected individuals is the pattern that best fits the actual study findings.