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.