CO2-induced panic attacks: A twin study

Objective: The authors investigated the role of genetic factors in 35% CO2-induced panic attacks. Method: Ninety twins recruited from the general population were challenged with one-vital-capacity inhalations of 35% CO2-65% O-2 Probandwise concordance rates were calculated and rates compared for monozygotic and for dizygotic twins. Results: A significantly higher concordance was found for 35% CO2-induced panic attacks among monozygotic than dizygotic twins (55.6% Versus 12.5%). Conclusions: These results suggest a relevant role of genetic factors in 35% CO2-induced panic attacks.