Auricular Vagal Neuromodulation Therapy (AVNT) significantly increases vagus nerve activity in healthy subjects [test template]

Abstract

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Study Design

Randomised Placebo Controlled

Study 1: Two-stages cross-over study compared the effects of Nurosym neuromodulation (tragus) and placebo stimulation (earlobe) on heart rate variability (HRV). Each participant underwent two visits, with the order of stimulation and placebo control randomised. Each visit comprised three phases: a 5-minute baseline period, a 5-minute stimulation period, and a 5-minute recovery period. During the stimulation period, participants received either Nurosym neuromodulation or placebo stimulation, while the effects of stimulation were assessed during the recovery period. Physiological data, including electrocardiogram (ECG) and respiratory data, were continuously recorded throughout the visits.

Statistical analyses were performed to compare the effects of Nurosym neuromodulation and placebo stimulation in Study 1 assessed parameter-specific effects of neuromodulation in Study 2. Various HRV parameters, including time-domain and frequency-domain indices, were analysed to evaluate the effects of stimulation on cardiac autonomic function.

Why is it important

The vagus nerve is a key component of the autonomic nervous system and plays a strategic role in the human body, acting as a bridge between the brain and various internal organs. It is involved in the regulation of many major systems, the activity of which is a marker of the parasympathetic nervous system and significantly inversely correlates with markers of inflammation. Therefore, increased cardiac vagal activity is proportionally associated with health, well-being, relaxation, and even emotions such as empathy. Conversely, decreased cardiac vagal activity is linked with risk factors such as morbidity, mortality, and stress. Nurosym, as a neuromodulation tool targeting vagal afferents, may have a powerful input to the brain and can influence a large number of physiological processes.

Results

Both the low frequency (LF) and high frequency (HF) components of heart rate variability serve as indicators of vagus nerve activity. The LF component reflects a blend of sympathetic and parasympathetic modulation, while the HF component, detected at 0.15–0.40 Hz, is specifically associated with parasympathetic modulation of heart rate. The study indicated an increase in the activity of the vagus nerve by approximately 61%, as measured by the HF component (*p < 0.0017, Nurosym neuromodulation vs. placebo stimulation), demonstrating significant effectiveness.

End points

Study 1: The Nurosym neuromodulation group was associated with significantly higher measures of cardiac vagal activity compared to placebo group. Notably, these effects persisted beyond the stimulation period, indicating a carry-over effect. Moreover, baseline LF/HF ratio emerged as a significant predictor of individual response to the vagus nerve neuromodulation, showing that individuals with higher sympathetic activity experienced greater autonomic benefits from the intervention.

Conclusion

Nurosym vagus nerve neuromodulation activates the parasympathetic nervous system through the vagus nerve, acting as a calming messenger in the body. Nurosym relays information to central vagal projections in the brain stem and higher centres, which, in turn, provide the efferent neural signal to the heart, ensuring the balance between the sympathetic and parasympathetic nervous systems. This connection makes it relevant in the treatment of many diseases, including neurodegenerative diseases, chronic pain, inflammation, and cardiovascular diseases.