Enhancement of Brain Circuit of Inhibitory Control in Obese Patients Undergoing Gastric Banding ("Neuroband")

"Neuroband": The Effect of Perioperative Enhancement of the Brain Circuit of Inhibitory Control in Obese Patients Undergoing Laparoscopic Adjustable Gastric Banding (LAGB)

In this project the investigators aim to improve eating control and weight loss outcomes in patients undergoing LAGB with an innovative brain-based intervention. Specifically, the investigators will enhance the activity of the right inferior frontal gyrus, a core region of the brain circuit of inhibitory control, using transcranial direct current stimulation (tDCS).

Laparoscopic Adjustable Gastric Banding (LAGB) is a minimally invasive and reversible procedure in bariatric surgery that has a good safety record. Despite these advantages, success rates following LAGB are quite variable across individuals. Recent data suggest that complementing LAGB with interventions targeting factors along the brain-behavior spectrum could enhance weight loss results following this procedure. The study will have the following three aims: Aim #1: To evaluate whether enhancement of the right inferior frontal gyrus with tDCS in patients undergoing LAGB can improve inhibitory control capacity. For this aim the investigators will evaluate participants' performance in a computerized test of inhibitory control. Results from this aim will provide evidence for target engagement, and thus confirm that the brain circuit of interest was affected as a result of the intervention. Aim #2: To examine whether enhancement of the right inferior frontal gyrus with tDCS in patients undergoing LAGB can lead to improvements in a self-reported measure of eating control (disinhibition subscale of the three-factor eating questionnaire). Results form this aim will provide evidence for an effect of the intervention on an intermediate, behavioral variable. Aim #3: To preliminary evaluate whether enhancement of the right inferior frontal gyrus with tDCS in patients undergoing LAGB can improve postoperative weight loss outcomes. This aim will provide preliminary evidence for the clinical efficacy of the intervention over a time window period of 12 months. Weight loss at 12 months will be the primary outcome of the study.

In this arm, participants will receive active tDCS (2mA, 20 min per session). The anode electrode will be placed over the right inferior frontal gyrus, defined as F8 (10-20 EEG system), with the cathode electrode placed over the contralateral supraorbital area, above the left eyebrow. During each session they will also perform a computerized task designed to engage the inhibitory control circuit when confronted with food stimuli.

Participants will receive sham tDCS sessions with the same duration and electrode montage as in the real tDCS arm. In this case, current will be applied for 30 s only according to standard procedures, and participants will perform a control task where they will observe and provide responses for the same food and non-food pictures as in the active group task, but without requirement of inhibitory control for performance.

tDCS is a well-established, safe and noninvasive neuromodulation technique that is based on the application of a weak direct current to the scalp that flows between two electrodes-anode and cathode. Although there is substantial shunting of current in the scalp, sufficient current penetrates the brain to modify the transmembrane neuronal potential, and thus influence the level of excitability and modulate the firing rate of individual neurons. In this study, participants will receive 10 daily sessions of tDCS (sham/real) over a period of two weeks.

Participants will be weighed at the indicated time points. Weight loss at 12 months will be the primary outcome of the study.

Baseline, 2 weeks after surgery, 10 days of tDCS, 1 month, 3 months, 6 months and 12 months follow up

Eating Disinhibition is an eating behavior trait that reflects a tendency towards overeating and eating opportunistically in an obesogenic environment. Examples include eating in response to negative affect, overeating when others are eating, not being able to resist temptations to eat, and overeating in response to the palatability of food (Bryant, King and Blundell. Obes Rev. 2008;9:409-19). Eating disinhibition was measured using the Three Factor Eating Questionnaire (TFEQ), which contains 16 questions for this factor. Responses are scored 0 or 1 and summed, thus eating disinhibition score ranges from 0 to 16. Higher scores denote higher levels of eating disinhibition.

Inhibitory control over food was measured with a Stop Signal Task that was modified with the presence of distractors of two types: images of food and neutral images (control). The Stop Signal Task is a computerized task that evaluates an individual's ability to interrupt a motor response after its initiation (Logan 1994). Subjects were asked to press a response key matching the direction of an arrow, but refrain from pressing when an auditory cue ("stop signal") appeared (25% trials). The main outcome of the task is the Stop-Signal-Reaction-Time (SSRT), in milliseconds, which reflects how long it takes to inhibit a response when a stop signal appears. The SSRT is considered a laboratory measure of inhibitory control capacity. Shorter SSRT reflects more efficient inhibitory control. Here a reduction of SSRT from baseline to 12 months indicates improvement in inhibitory capacity. We provide SSRT changes for food and neutral images, reflecting specific and general effects, respectively.

Inclusion Criteria: Age: 20-55 years old BMI: 35-60 kg/m2 Planning to undergo or having undergone laparoscopic adjustable gastric banding (LAGB) within the previous week Exclusion Criteria: Unstable medical conditions including poorly controlled diabetes and hypertension Pregnancy or planning pregnancy during study period Personal or family history of epilepsy or other unexplained loss of consciousness Current or past medical history of skin disease or damaged skin on the scalp at site of stimulation Active psychiatric or neurological condition Prior neurological procedure Implanted pacemaker, medication pump, vagal stimulator, deep brain stimulator, TENS unit, or ventriculoperitoneal shunt Intake of common medications that affect the central nervous system will be allowed if determined okay by MD

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