Effectiveness of bipolar-balanced prefrontal tDCS in patients with borderline personality disorder: Results from a randomized, double-blind, sham-controlled trial

Abstract

Introduction: Preliminary evidence suggested that transcranial Direct Current Stimulation (tDCS) could improve Borderline Personality Disorder (BPD) symptoms, including impulsivity and emotion dysregulation. However, substantial heterogeneity in stimulation protocols and small sample sizes preclude definitive conclusions.

Methods: This double-blind RCT (active versus sham) investigated whether 15 daily sessions of bipolar-balanced prefrontal (anodal right DLPFC/cathodal left DLPFC) effectively reduced impulsivity and decision-making (primary outcomes). Improvements of depressive-anxiety symptoms, aggressiveness, working memory and sustained attention represented secondary outcomes. Within-group and between-groups effects were evaluated with Paired sample t-tests and Analyses of Covariance (ANCOVA), respectively.

Results: 50 BPD individuals completed the study (both groups, n = 25). tDCS improved several aspects of impulsivity, mainly Non-planning impulsivity. While active-tDCS significantly improved decision-making, ANCOVA failed to demonstrate meaning treatment effects. Active-tDCS significantly improved depressive-anxiety symptoms, producing the largest response and remission rates if compared to sham treatment. Notably, mood symptoms improved independently of baseline impulsivity and emotion regulation scores. tDCS also improved sustained attention but did not affect aggression nor working memory. In highly impulsive BPD individuals, tDCS confirmed its effectiveness in reducing impulsivity and depressive-anxiety symptoms, and provides preliminary evidence of improved emotional competence.

Limitations: The study lacks a follow-up to evaluate the durability of tDCS after-effects and neuroimaging data to understand the biological impact of tDCS over aberrant frontolimbic networks linked to BPD symptoms.

Conclusions: These findings contribute to reduce heterogeneity in NIBS protocols, suggesting that this tDCS protocol is an effective treatment option to improve impulsivity and reduce affective symptoms in BPD individuals.

Keywords: Attention; Borderline personality disorder; Decision-making; Depressive symptoms; Emotion regulation; Impulsivity; tDCS.