Resting-state and task-evoked phase-amplitude coupling between cardiac and neural rhythms is sensitive to anxiety severity

Resting-state phase-amplitude coupling between cardiac and neural rhythms is influenced by anxiety severity, according to a recent study. High-frequency heart-rate variability (HF-HRV), a downstream marker of cortico-autonomic regulation, is linked to executive function. The study aimed to assess the brain-body correspondence between HF-HRV and EEG oscillations in relation to anxiety symptoms.

The researchers recorded EEG and electrocardiography (ECG) signals in 22 nonclinical adults while they were at rest and performing a mental arithmetic task. Participants assessed their anxiety severity using the Generalized Anxiety Disorder 7-item scale (GAD-7). The study found that higher anxiety levels were associated with decreased resting-state phase-amplitude coupling between HF-HRV phase and fronto-central theta amplitude.

Interestingly, during the cognitive task, HF-HRV-theta coupling increased, independent of changes in EEG, heart rate, or respiration. Moreover, anxiety severity moderated the task-evoked changes in heart-brain coupling, with more anxious individuals displaying larger differences in coupling.

The results suggest that HF-HRV-theta phase-amplitude coupling may index a state-sensitive component of cortico-autonomic regulation. This coupling captures anxiety-related and state-dependent variance not evident in conventional cardiac or neural indices. However, further direct testing is required to determine the functional role of this coupling.