Advances in non-invasive brain stimulation for borderline personality disorder: clinical targets and future directions - an updated narrative review.

INTRODUCTION: Borderline Personality Disorder (BPD) remains a major therapeutic challenge, given incomplete response to first-line psychotherapies and limited treatment accessibility. Non-Invasive Brain Stimulation (NIBS), particularly repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS), has emerged as promising interventions. METHODS: This narrative review provides an updated overview of recent evidence on NIBS in BPD, focusing on: new tDCS studies, NIBS to improve interpersonal dysfunction and social cognition, the combination between NIBS and psychotherapies, and the role of comorbid BPD as a moderating factor on NIBS outcomes. RESULTS: Preliminary evidence supports a symptom-oriented application of NIBS in BPD: right dorsolateral prefrontal cortex (DLPFC) stimulation appears mainly associated with improvements in impulsivity, whereas left DLPFC stimulation improves emotion regulation and cold cognitive functioning. Emerging studies targeting the right ventrolateral prefrontal cortex suggest beneficial effects on rejection-related emotional responses and interpersonal sensitivity. Studies combining NIBS with psychotherapy show acceptable feasibility profiles, although additive effects remain uncertain. Available evidence also suggests that comorbid BPD may not substantially impair antidepressant response to NIBS. CONCLUSIONS: NIBS represents a promising adjunctive intervention for BPD. However, larger sham-controlled trials, biomarker-informed studies, replication studies, and long-term follow-up assessments are needed before definitive clinical recommendations can be established.