Transcutaneous auricular vagus nerve stimulation and emotional responding in borderline personality disorder: a...

Borderline personality disorder (BPD) is characterized by severe emotional vulnerability, including heightened sensitivity, exaggerated reactivity, and delayed recovery from emotional arousal. Altered interoceptive-affective processing may contribute to these features. Transcutaneous auricular vagus nerve stimulation (taVNS) provides a non-invasive method for modulating vagal-afferent pathways involved in interoception and emotion regulation. This study examined whether active taVNS, relative to sham stimulation, was associated with lower self-reported negative affect during a video-based mood-induction paradigm in women with BPD.

Thirty-four female psychiatric outpatients with DSM-5 BPD were randomized to receive active taVNS or sham stimulation during a single-session experimental paradigm. Self-reported negative affect was assessed repeatedly using the Positive and Negative Affect Schedule (PANAS) Negative Affect scale. The primary analysis modeled PANAS Negative Affect across four collapsed task phases: Pre-Induction, Post-Neutral, Post-Negative, and Recovery-Negative, adjusting for baseline negative affect and stimulation intensity. Exploratory physiological analyses examined heart rate, lnRMSSD, phasic electrodermal activity (EDA) response frequency, and tonic skin conductance level.

Active taVNS was associated with lower PANAS Negative Affect across the mood-induction paradigm compared with sham stimulation, Treatment Group: F(1, 36.44) = 5.74, p = 0.022. Negative affect varied significantly across task phases, F(3, 94.12) = 22.60, p < 0.001, confirming successful mood induction. The Treatment Group × Phase interaction was not significant, F(3, 94.12) = 0.75, p = 0.525. Exploratory physiological analyses showed no treatment-related effects on heart rate, lnRMSSD, or phasic EDA response frequency. Tonic skin conductance level showed no main effect of Treatment Group, but an exploratory Treatment Group × Epoch interaction.

In this preliminary single-session randomized sham-controlled study, active taVNS was associated with lower self-reported negative affect during a mood-induction paradigm in women with BPD. This subjective effect was not accompanied by treatment-related effects on heart rate, lnRMSSD, or phasic EDA response frequency, while the tonic skin conductance interaction should be interpreted cautiously as exploratory. These findings support further investigation of taVNS as a mechanistic probe of acute affective responding in BPD.

ClinicalTrials.gov NCT05892900. Retrospectively registered 7 June 2023.