The study aims to evaluate the impact of transcranial direct current stimulation (tDCS) on impulsiveness of adults suffering from Borderline Personality Disorder. Short- and long-term effects are assessed by electroencephalography (EEG) records, experimental tasks and self-rated scales.

Impulsivity, considered as the tendency to express spontaneous, excessive and/or unplanned behavior, is recognized as a major factor involved in suicidal behavior and self-harm behaviors. It consists in one of the diagnostic criteria of Borderline Personality Disorder, allowing as well assessment of its clinical severity. There is so far no specific treatment concerning impulsivity. From a neurobiological perspective, the prefrontal cortex is considered as a critical region in the cognitive control of behaviors. Previous studies have associated an hypoactivation of the dorsolateral prefrontal cortex (dlPFC) and the dorsal part of the anterior cingulate cortex to Borderline Personality Disorder.

Transcranial direct current stimulation (tDCS) is a technique of noninvasive brain stimulation which delivers a subthreshold electrical current to the scalp, manipulating the resting membrane potential. It has shown cognitive function improvement, both in healthy individuals and psychiatric populations. Modulation of the dlPFC could therefore represent a mean of reducing impulsivity in those patients.

With a prospective, sham-controlled, crossover, double-blind design, this study aims to evaluate the impact of bilateral tDCS over the dlPFC on the impulsive dimension of adults suffering from Borderline Personality Disorder. Subjects will be submitted to 10 tDCS stimulation sessions (active or sham) for five consecutive days (2 sessions of 30 minutes/day). Current intensity will be of 2 mA, through 25 cm² surface electrodes, placed over the dlPFC (anode position over F4 and cathode over F3, according to the EEG 10-20 international system). Subjects who undergo active stimulation sessions will be then submitted to sham sessions and vice-versa. Baseline measures will be compared to those obtained immediately after the end of sessions (5 days: short-term effects), and to 12 and 30 days later (long-term effects). Active and sham stimulation sessions outcomes will as well be compared.

Inclusion Criteria:

• Man or woman older than 18 years old
• Right-handed
• Signed Informed Consent form
• Subject affiliated to or beneficiary from a French social security regime
• Inpatient or outpatient at the Adult Psychiatry Service
• Diagnosis of Borderline Personality Disorder according to the 5th edition of Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria and confirmation by the Structured Clinical Interview for DSM Disorders (SCID-II)
• Absence of addictive comorbidities (except: tobacco, tea, coffee)
• Absence of severe progressive neurologic and/or somatic pathologies (specially tumors, degenerative diseases)

Exclusion Criteria:

• Younger than 18 years old
• Left-handed
• Subject under measure of protection or guardianship of justice
• Presence of psychiatric comorbidities (chronic psychosis, Bipolar Disorder)
• Subject beneficiary from a legal protection regime
• Subject unlikely to cooperate or low cooperation stated by investigator
• Subject not covered by social security
• Pregnant woman
• Subject being in the exclusion period of another study or provided for by the "National Volunteer File"