(55) ACUTE EFFECT OF PERIPHERAL NERVE STIMULATION ON COGNITIVE PERFORMANCE FOLLOWING HIGH-INTENSITY EXERCISE IN TACTICAL PERSONNEL WITH CONCUSSION HISTORY

Military personnel undergo unique physical and mental stressors which can compromise cognitive performance. Prior research demonstrates transcutaneous vibroacoustic stimulation (TVAS) of afferent nerves modulates autonomic nervous system (ANS) activity to enable more efficient and appropriate efferent output for a task, which may enhance cognitive performance. 

Purpose: Evaluate acute effects of TVAS on cognitive performance following high-intensity interval exercise in asymptomatic tactical personnel with a history of remote concussion. METHODS: Thirty-four participants (M=24, F=10; age=21.6±4.0 y) completed one baseline and two experimental sessions. The baseline session included a VO₂max test and familiarization with traditional (Hopkins Verbal Learning Task [HVLT] and validated color-shape switch task) and functional (a go/no-go reaction task using the Dynavision D2^TM board) cognitive tasks. Experimental sessions, one sham and one active stimulation, were randomized, counterbalanced, and separated by 3-7 days. During experimental sessions, participants wore the ApolloNeuro™ device proximal to the lateral malleolus to deliver TVAS at specific frequencies. Participants were instructed they would be receiving low-intensity and high-intensity conditions in experimental sessions. During the sham condition, the TVAS settings were ramped-up to 50% intensity over 2.5 minutes, then down to 0% over the next 2.5 minutes. The intensity remained at 0% for the rest of the session. During the active condition, the TVAS was set to the “Focused” setting and was ramped up to 50% over 5 minutes; this intensity was maintained for the entire session. For experimental sessions, participants completed the battery of cognitive tasks before and after a 20-minute high-intensity interval treadmill protocol composed of 1-minute work intervals at 115% VO_2max interspersed with 1-minute recovery intervals at 40% VO_2max. After a 1-hour rest, participants completed the final HVLT word recall and word recognition. Omnibus analyses were performed to evaluate pre- to post-exercise change scores for all go/no-go and color-shape switch tasks and pre- to post-recovery for HVLT tasks within and between conditions (α=0.05). 

Results: Active stimulation led to greater cognitive performance improvements following high-intensity exercise compared to sham stimulation in terms of reaction time cost for the no-go condition of the go/no-go task (p=0.02). For the color-shape switch task, there were greater improvements in the active condition for omission errors (p=0.01) and inverse efficiency for the mixed rule set condition (p=0.03), and omission errors for the global switch cost (p=0.02). There were no significant differences for HVLT tasks (p >0.05). 

Conclusions: The current study indicates TVAS may acutely improve cognitive task performance by enhancing cognitive control, reducing lapses of attention, and reducing reaction time following high-intensity exercise. TVAS may enhance cognitive resilience and performance, particularly following high-intensity physical efforts. PRACTICAL APPLICATION: TVAS may be a promising tool to enhance tactical personnel's cognitive resilience and rapid decision-making. Integrating non-invasive ANS modulating techniques may help optimize cognitive readiness and task performance following intense physical efforts. The application of TVAS may extend beyond tactical populations to other domains facing similar cognitive and physical demands.

Acknowledgements:

ACKNOWLEDGEMENTS: This project was funded by a grant from the non-profit Board of Medicine awarded to SMA & RDM. This project was also made possible in part by Grant Number T32-GM081740 from NIH-NIGMS. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the Board of Medicine nor the NIGMS or NIH.