Family history of panic disorder and hypersensitivity to CO2 in patients with panic disorder

OBJECTIVE: The authors investigated the relationships between hypersensitivity to CO2 and familial-genetic risk for panic disorder in patients with panic disorder. METHOD: Morbidity risks for panic disorder were calculated for families of 203 patients with panic disorder, each of whom was challenged with 35% CO2. RESULTS: Patients who reacted with a positive response to the 35% CO2 challenge showed a genetic risk for panic disorder (morbidity risk = 14.4%) that was significantly higher than that for patients who did not react (morbidity risk = 3.9%). CONCLUSIONS: These findings support the idea that hypersensitivity to CO2 might be associated with a subtype of panic disorder specifically related to a greater familial loading.