Carbon dioxide hypersensitivity in separation-anxious offspring of parents with panic disorder

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.

Figure 1

Figure 1 presents API scores generated with the SAS Mixed model procedure. Estimated API scores are adjusted for all variables (i.e., baseline API, offspring age, Parental PD, Offspring SAD, and Trial effect) in the model.

Figures 2a and 2b

Figures 2a and 2b present estimated respiratory frequency (fR) and tidal volume (V_T) values, respectively, of offspring with and without SAD of parents with or without a history of PD across 5 minutes of 5% CO₂ inhalation. Respiratory frequency and tidal volume values are adjusted for all variables (i.e., baseline, offspring age, offspring BMI, Parental PD, Offspring SAD, and Trial effect) in the model.

Figure 3

Figure 3 presents log transformed panting ratio (V_T / fR) values across 5 minutes of 5% CO₂ breathing for offspring with and without SAD of parents with or without a history of PD. Panting ratio values are adjusted for all variables (i.e., baseline, offspring age, offspring BMI, Parental PD, Offspring SAD, and Trial effect) in the model.