Neural and physiological associations between 7.5% CO2-evoked panic and anticipatory anxiety in healthy individuals

Authors

• JY Liu
• NL Balderston
• M Ernst
• C Grillon

Abstract

Panic disorder (PD) is characterized by heightened anticipatory anxiety, as indexed by anxiety-potentiated startle, but this abnormality may also manifest along a continuum of panic sensitivity (PS) in healthy individuals. This study investigated associations among PS, as assessed with behavioral and autonomic responses to CO2, startle potentiation and brain measures of anticipatory anxiety in healthy individuals. Subjects inhaled a 7.5% CO2 challenge agent for a total of 8 minutes. PS was quantified using physiological measures (N=49) and subjective report of panic symptoms (N=60) under CO2 inhalation. Subjects also completed the “NPU threat” task consisting of alternating blocks of safe conditions (no (N) shock) and two threat conditions –predictable (P) shock signaled by a cue and unpredictable (U) shock. Anticipatory anxiety during the threat of predictable and unpredictable shock was compared to safe periods when no shock could be administered in two separate sessions, one to assess startle potentiation (N=60) and the other to investigate BOLD activity (fMRI: N=46). Subjective report of panic symptoms under CO2 significantly correlated with subjective anxiety and fear in the predictable and unpredictable threat conditions. Importantly, preliminary analysis show significant correlations between subjective reports of palpitations under CO2 and fear-potentiated startle, suggesting a link between panic symptoms and fear and anxiety symptoms. Expanding upon these preliminary findings, our current analyses examine the link between panic sensitivity and BOLD activity in the network underlying fear and anxiety.

Scientific Focus Area: Neuroscience

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