tVNS and obesity-related inflammation: a prospective sham-controlled randomized crossover study protocol

Area of Science:

• Neuroscience
• Immunology
• Metabolic Health

Background:

• Overweight and obesity are linked to chronic low-grade inflammation (metaflammation) impacting energy metabolism and mental well-being.
• The cholinergic anti-inflammatory pathway (CAIP), modulated by vagus nerve stimulation (VNS), offers a potential therapeutic target.
• Previous research on non-invasive transcutaneous VNS (tVNS) for inflammation is limited, with no studies on daily home-based application for obesity.

Purpose of the Study:

• To evaluate the effects of daily home-based transcutaneous vagus nerve stimulation (tVNS) on inflammation, mood, and motivation in individuals with elevated BMI.
• To investigate the potential of tVNS to modulate peripheral and central inflammatory markers.
• To explore the relationship between inflammation, mood, and motivation in the context of obesity.

Main Methods:

• A single-blind, randomized crossover study involving 60 participants (BMI 27-35 kg/m²) self-administering high- and low-intensity tVNS daily for 14 days each, with a 7-day washout period.
• Assessment of peripheral inflammation (cytokines, immune cells) and central inflammation (diffusion-weighted imaging).
• Evaluation of motivation via fMRI effort allocation task and mood via daily ecological momentary assessments, alongside food choice monitoring.

Main Results:

• This section is not available in the provided abstract, as the study is ongoing.
• The study is designed with sufficient statistical power to detect significant differences.
• Mixed-effects models will be used to analyze differences in outcomes between high- and low-intensity tVNS.

Conclusions:

• The study employs a 14-day home-based tVNS protocol with daily assessments to examine mid-term effects on inflammation, mood, and motivation.
• The multimodal design allows integration of inflammatory and behavioral outcomes, providing evidence for tVNS efficacy in chronic inflammation.
• Results may offer pathophysiological insights into the obesity-depression link via inflammation and guide future VNS therapies for overweight and obesity.