Abstract
BACKGROUND: Similar patterns of vulnerability to carbon dioxide (CO(2)) inhalation have been reported in adults with panic disorder (PD) and children with separation anxiety disorder (SAD), suggesting a link between the adult and child conditions. This study examines the influence of familial risk for PD on CO(2) responses in children with SAD. We hypothesized that offspring with SAD of parents with PD would have distinct CO(2) responses. METHODS: Two hundred twelve 9- to 20-year-old offspring of parents with or without PD were exposed to maintained 5% CO(2) inhalation in the participants' homes. Anxiety symptoms, panic attacks, and respiratory physiology (respiratory frequency and tidal volume) were monitored during baseline and 15-min maintained CO(2) breathing. RESULTS: As hypothesized, significant offspring SAD x parent PD interactions were obtained for anxiety symptoms, respiratory frequency, tidal volume, and a panting index during CO(2) inhalation. Offspring with both SAD and parental PD exhibited more anxiety symptoms at termination of 5% CO(2) breathing than the other offspring groups and had the most extreme values on measures of respiratory physiology. CONCLUSIONS: Youth with both SAD and parental PD have respiratory responses to CO(2) similar to adult PD. They might be a subtype of SAD at particularly high risk for adult PD.