Brain-heart coupling in response to imminent threat in panic disorder, social anxiety disorder, and healthy controls

Imminent threat does not only capture attention but also triggers defensive psychophysiological responses associated with fight-flight-freeze behavior. However, within-subject associations between central markers of attentional stimulus processing and peripheral components of early defensive activation (e.g., cardiac acceleration) are not well understood. These associations may be especially important in understanding dynamics of anxiety disorders that are characterized by cardiovascular symptoms such as panic disorder.

We analyzed data from N = 90 participants with panic disorder (PD), social anxiety disorder (SAD), as well as healthy controls (CG) who completed a threat conditioning paradigm with face stimuli as conditioned stimuli (CS) and an aversive white noise burst as unconditioned stimulus (US). In addition to univariate analyses of ERPs and heartbeat, single-trial EEG evoked by the noise burst at centromedial sites and heart period were used to calculate intraindividual coupling of unconditioned cortico-cardiac responses.

The noise burst evoked strong cardiac acceleration and an event-related potential with a pronounced N100 component. Importantly, the magnitude of single-trial cardiac acceleration was predicted within individuals by the preceding single-trial N100 magnitude. This cortico-cardiac coupling, but not the N100 component or cardiac acceleration per se, was enhanced in individuals with panic disorder compared to social anxiety disorder, with intermediate levels of coupling observed in healthy controls.

The present results suggest a central role of early attentional stimulus processing in subsequent cardiac defensive responses. Furthermore, they indicate that cortico-cardiac defensive responses may be altered in individuals with panic disorder specifically, rather than in anxiety disorders in general.