To examine the relationship between respiratory regulation and childhood anxiety disorders, this study considered the relationship between anxiety disorders and symptoms during carbon dioxide (CO2) exposure, CO2 sensitivity in specific childhood anxiety disorders, and the relationship between symptomatic and physiological responses to CO2.
Following procedures established in adults, 104 children (aged 9-17 years), including 25 from a previous study, underwent 5% CO2 inhalation. The sample included 57 probands with an anxiety disorder (social phobia, generalized anxiety disorder, separation anxiety disorder, and panic disorder) and 47 nonill comparison subjects. Symptoms of anxiety were assessed before, during, and after CO2 inhalation.
All children tolerated the procedure well, experiencing transient or no increases in anxiety symptoms. Children with an anxiety disorder, particularly separation anxiety disorder, exhibited greater changes in somatic symptoms during inhalation of CO2-enriched air, relative to the comparison group. During CO2 inhalation, symptom ratings were positively correlated with respiratory rate increases, as well as with levels of tidal volume, minute ventilation, end-tidal CO2, and irregularity in respiratory rate during room-air breathing.
Childhood anxiety disorders, particularly separation anxiety disorder, are associated with CO2 hypersensitivity, as defined by symptom reports. Carbon dioxide hypersensitivity is associated with physiological changes similar to those found in panic disorder. These and other data suggest that certain childhood anxiety disorders may share pathophysiological features with adult panic disorder.