Temporal stability of multiple response systems to 7.5% carbon dioxide challenge

Area of Science:

• Psychophysiology
• Clinical Psychology
• Neuroscience

Background:

• Self-reported anxiety and physiological responses to carbon dioxide (CO2) inhalation show potential as markers for panic reactivity and vulnerability.
• However, the temporal stability of these response systems during low-dose, steady-state CO2 breathing challenges is not well-established.

Purpose of the Study:

• To assess the temporal stability of various physiological and psychological outcomes during a CO2 breathing challenge.
• To determine if CO2 inhalation can serve as a reliable measure of panic reactivity over time.

Main Methods:

• Ninety-three participants underwent a CO2 breathing challenge on two separate occasions, one week apart.
• Multiple outcome measures, including self-reported anxiety, respiratory rate, skin conductance level, heart rate, cognitive symptoms, escape/avoidance behaviors, and DSM-5 panic attacks, were recorded.
• Intraclass correlation coefficients (ICCs) were used to evaluate temporal stability.

Main Results:

• Anxiety ratings, respiratory rate, skin conductance level, and heart rate demonstrated good to excellent temporal stability (ICCs ≥ 0.71) during the CO2 breathing phase.
• Cognitive panic symptoms were less stable (ICC=0.58) than physical symptoms (ICC=0.74) during CO2 exposure.
• Escape/avoidance behaviors and DSM-5 panic attacks showed poor temporal stability.
• Significant effect sizes were observed between different task phases (pre-CO2, CO2 breathing, recovery).

Conclusions:

• Multiple physiological and self-reported anxiety measures exhibit good to excellent temporal stability during a 7.5% CO2 breathing challenge.
• The CO2 challenge appears to be a reliable tool for assessing panic reactivity and vulnerability, particularly for physical symptoms.
• Further research may be needed to refine the assessment of cognitive symptoms and behavioral outcomes for panic reactivity using this method.