Response to 5% carbon dioxide in children and adolescents - Relationship to panic disorder in parents and anxiety disorders in subjects

Background: Carbon dioxide (CO2) sensitivity is postulated to be a familial risk marker of panic disorder (PD). Exaggerated responses to CO2 inhalation have been reported in adults with PD and their unaffected adult relatives, as well as in clinic-referred children with anxiety disorders. Objective: To test in a family-based design whether CO2 hypersensitivity is a familial risk marker for PD and associated with current anxiety disorders in children and adolescents. Setting and Participants: One hundred forty-two offspring (aged 9-19 years) of parents with PD, major depressive disorder, or no disorder. Forty-five (32%) had a current anxiety disorder, excluding specific phobia. Design and Main Outcome Measures: Parents and offspring received diagnostic assessments. Offspring underwent 5% CO2 inhalation at home. Panic symptoms and panic attacks were rated with the Acute Panic Inventory at baseline, while anticipating CO2 delivery (threat), and during CO2 inhalation. Respiratory rate and volume were measured with spirometry. Results: No group differences were found in Acute Panic Inventory ratings at baseline or in respiratory measures during threat. Risk for PD was not associated with CO2 sensitivity (panic symptoms and respiratory physiologic response). During CO2 inhalation, offspring with anxiety disorders, relative to offspring without anxiety disorders, experienced significantly more panic symptoms and panic attacks, as well as elevated respiratory rates. During threat, panic symptoms were significantly and independently associated with both parental PD and offspring anxiety disorders. Conclusions: No support was obtained for CO2 hypersensitivity as a familial risk marker for PD in children and adolescents. Links between childhood anxiety disorders and CO2 sensitivity were replicated. Familial risk for PD in children and adolescents may be associated with vulnerability to anticipatory anxiety.