Repeated transcranial direct current stimulation of dorsolateral-prefrontal cortex improves executive functions, cognitive reappraisal emotion regulation, and control over emotional processing in borderline personality disorder: A randomized, sham-controlled, parallel-group study

Borderline personality disorder (BPD) is primarily characterized by deficient emotion regulation. Impaired cognitive control over negative emotions is central to emotion dysregulation in BPD. Respective executive dysfunctions are associated with hypoactivation of prefrontal regions, and consecutive alterations of fronto-limbic network functionality. Here, we investigated the effect of increasing activity of the dorsolateral prefrontal cortex (DLPFC) with repeated transcranial direct current stimulation (tDCS) on (1) executive dysfunctions and (2) whether improving cognitive control affects emotion dysregulation and emotional processing in BPD. Thirty-two patients diagnosed with BPD were randomly assigned to active stimulation (N = 16) or sham stimulation (N = 16) group in a randomized, sham-controlled, parallel-group design. They received 10 sessions of active (2 mA, 20 min, anodal left- cathodal right DLPFC) or sham tDCS over 10 days. Major executive functions, emotion regulation strategies, and emotional processing of the patients were assessed before and immediately after the intervention. The active stimulation group showed a significant improvement in major executive function domains. Importantly, cognitive reappraisal strategy of emotion regulation and several factors of emotional processing involved in the control of emotion significantly improved in the active stimulation group after the intervention. Factors related to emotional expression were, however, not affected. The single-blind design, absence of follow-up measures, and the intrinsically limited focality of tDCS are limitations of this study. Increasing activity of the DLPFC improves executive functioning in BPD and improves ´cognitive control over negative emotions. Cognitive control interventions could be a potential, symptom-driven therapeutic approach in BPD.