Clinical Correlates of Carbon Dioxide Hypersensitivity in Children

OBJECTIVE

Hypersensitivity to carbon dioxide (CO₂)-enriched air may be a promising risk marker for anxiety disorders. Among adult and adolescent samples, heterogeneity in distress response to the CO₂ challenge task indexes 3 underlying classes of individuals, which distinguish between sustained and acute threat response as markers for internalizing disorders, broadly, and anxiety disorders, specifically. The present study examines latent classes in children's response to the CO₂ challenge task to clarify the association of CO₂ hypersensitivity with anxiety and internalizing symptomatology in childhood.

METHOD

Healthy children from a community twin sample (N = 538; age 9-13 years) rated anxious distress every 2 minutes while breathing air enriched to 7.5% CO₂ for 8 minutes. Latent growth mixture modeling evaluated potential classes of individuals with characteristic trajectories of distress during the task to clarify the association with internalizing disorder symptoms and related traits (e.g., anxiety sensitivity, irritability).

RESULTS

Although all participants reported increased distress during the task, interindividual heterogeneity in distress indexed 3 underlying classes: a consistently low class ("low"), a consistently high class ("high"), and participants who demonstrated markedly increased acute distress ("acute"). Compared to the low class, the high class reported greater internalizing psychopathology, whereas membership in the acute class was associated with experiencing a panic-like event during the task.

CONCLUSION

As in older individuals, 3 distinct trajectories emerged to capture interindividual heterogeneity in children's distress during the CO₂ challenge task. These classes were distinguished by clinical validators that reinforce the association of CO₂ hypersensitivity and internalizing disorder phenotypes in children.

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

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.