Effect of home-based transcranial direct current stimulation associated with nutritional counseling therapy on clinical and electrophysiological measures in Binge eating disorder: a study protocol for a blind, randomized, controlled clinical trial

Background: Binge Eating Disorder (BED) is a psychiatric disorder that has several medical and social consequences. Cognitive Behavioral Therapy (CBT) is the reference treatment, but presents significant dropout rates and elevated failure of therapeutic response. Therefore, new therapies targeting Central Nervous System (CNS) modulation, such as transcranial direct current stimulation (tDCS), might improve therapeutical responses, by modulating cognitive control over eating behavior and/or by enhancing inhibitory control due to synergistic action when combined with the current treatments available. Methods: Women with moderated BED, aged between 18 and 65 years and BMI ≥ 25 Kg/m² will be included. The participants will be divided into one of four groups: (1) Active tDCS; (2) Nutritional Counseling Therapy (NCT); (3) Active tDCS + NCT; (4) Sham tDCS + NCT. The electrodes of the tDCS will be positioned over the right Dorsolateral Pre-Frontal Cortex (DLPFC) - anode and left DLPFC - cathode. The participants will have a weekly appointment for 8 weeks where they will undergo the stimulation and/or the NCT. The groups that have the tDCS therapy will also receive the stimulation at home 4x/week in the first 5 weeks. The follow up is 8 weeks. The primary outcomes are the severity of symptoms, measured by the Binge Eating Scale (BES), and the inhibitory parameters of cortical excitability, measured by Transcranial Magnetic Stimulation (TMS) - Short Intracortical Inhibition (SICI). The secondary outcomes are weight loss, eating behavior, inhibitory control (Go/No-go), parameters of cortical excitability (Intracortical Facilitation (ICF) and cortical silent period (CSP)), and serum levels of leptin. Discussion: Cumulative research has provided evidence that tDCS improves disordered eating behaviors. Nevertheless, studies investigating the efficacy of long-term tDCS combined to standard treatment to BED are scarce. Based on exciting findings in trials that have associated tDCS and cognitive-behavioral approaches in Major Depressive Disorder (MDD), we hypothesize that the proposed protocol will be able to amplify therapeutical responses by reducing the severity of BED symptoms and enhancing inhibitory pathways assessed by cortical excitability parameters.