Non-invasive transcutaneous vagal nerve stimulation enhances mood, task performance, and learning in a high-stress military training environment

Abstract

Non-invasive transcutaneous vagal nerve stimulation (tVNS) has been shown to accelerate learning and performance in Air Force (USAF) personnel while simultaneously increasing attention, arousal, and mood in well-controlled laboratory tasks. The purpose of this study was to evaluate the effect of tVNS on operational performance, cognitive function, and mood in Air Force trainees undergoing the third week of their Military Qualification Training (MQT) course, the most difficult and fast-paced portion of their curriculum. Methods: USAF trainees were randomly assigned to receive active tVNS or a sham device. On days 1 through 4, trainees completed a 15-item mood questionnaire (pre-task) followed by tVNS or sham, MQT tasks, another round of tVNS or sham, and a final mood questionnaire (post-task). They completed a third mood questionnaire at the end of each day (EOD). Stimulation consisted of 2 minutes of tVNS or sham on one side of the neck followed by a 2-minute break and then 2 more minutes of tVNS or sham on the other side of the neck. Mood was measured using a 7-point numeric rating scale. A mixed-model ANOVA, with “group” as a between-subjects factor and “day” as a within-subjects factor, was used to assess mood changes from pre-task Day 1 ratings to all post-task ratings for each day and pre-task Day 1 ratings to all EOD ratings, as well as changes in task performance. Results: A total of 70 trainees completed the study (39 active, 31 sham). Trainees who received tVNS reported reduced distress (Distressed/Delighted, p<0.001), increased ability (Able/Unable, p=0.020), increased energy (Fatigued/Energized, p=0.002), and an improvement in overall mood (p=0.026) from pre-task Day 1 to all post-task ratings, compared to the sham group. Increased energy (p=0.034) and reduced distress (p=0.042) were maintained at EOD for those receiving tVNS compared with sham. There was a trend toward increased focus (Focused/Distracted, p=0.064) from pre-task Day 1 to all post-task ratings for tVNS vs sham. For performance of MQT tasks, trainees receiving tVNS demonstrated a significant increase in the ability to produce full motion video (FMV)-derived intelligence products in support of mission tasking compared to sham (p=0.020). A significant effect of tVNS compared with sham was observed on Day 1 for the “perform FMV callouts using the appropriate format” and “conduct a target walk-on target verification” tasks. tVNS produced additional performance benefits that did not reach statistical significance. Conclusions: This is the first demonstration of tVNS in a high-stress, high-performance real-world operational training environment. Trainees receiving tVNS saw improvements in several measures of operational readiness, were significantly more energetic, less stressed, and felt better able to perform the required tasks. These operational and mood related improvements in FMV-related tasks suggest that tVNS could be deployed to enhance warfighter training and operational readiness.

Keywords: transcutaneous vagus nerve stimulation, accelerated learning, military

DOI: 10.54941/ahfe1006947