Reactivity to a 35% CO2 challenge in healthy first-degree relatives of patients with panic disorder

Background: The effects of a 35% CO2 challenge were examined in healthy fir st-degree relatives of panic disorder patients and in healthy control subje cts matched for age and gender. Methods: One single inhalation of a 35% CO2/65% O-2 challenge was administe red to 50 first-degree relatives of panic disorder patients and 50 control subjects. Results: The first-degree relatives were more reactive to the 35% CO2 chall enge than the control subjects. Conclusions: These findings indicate that being a member of a family with a panic disorder patient is, in itself, an important factor in CO2 hypersens itivity among subjects who have never experienced a panic attack. Both pani c disorder patients and their first-degree relatives have a tendency to be more reactive to the CO2 challenge. Biol Psychiatry 2000:47:830-835 (C) 200 0 Society of Biological Psychiatry.