The Effect of Cervical Transcutaneous Vagus Nerve Stimulation on Word Memory in Healthy Adults: A Randomized Single-Blind Study.

Abstract

Purpose: The noninvasive vagus nerve stimulation has presented a promising adjunctive intervention in cognitive communication disorders. This randomized single-blind study aims to investigate the effect of cervical transcutaneous vagus nerve stimulation (tVNS) on verbal memory in healthy adults.

Method: Thirty-one participants were stratified into an experimental group (n = 22) receiving 30-min cervical tVNS and a control group (n = 9). Both groups completed a self-paced task to learn 50 Chinese words, followed by an immediate memory test and a 2-week delayed memory test assessing accuracy and reaction time (RT). Data of accuracy and RT were analyzed statistically based on tVNS stimulation, two sessions of memory test, and three age groups.

Results: Cervical tVNS significantly improved memory performance, manifested in faster RT and higher accuracy compared to the control group, particularly for young adults. However, accuracy enhancement was age-specific: Only younger adults showed significantly improved recall accuracy with cervical tVNS, while middle-aged and older adults did not. A significant three-way interaction (Group × Session × Age) indicated that cognitive benefits from cervical tVNS were not uniform across the lifespan.

Conclusions: A single cervical tVNS session can modulate verbal memory, primarily speeding RT, but its effects on accuracy are contingent on age. This underscores cervical tVNS as a neuromodulatory tool whose efficacy is filtered by the neurobiological state, highlighting the need for personalized, age-considered protocols in clinical translation.