Effects of Brain Stimulation on Food Intake and Behavioral Weight Loss Treatment

Overview

This study will determine whether electrical stimulation of an area of the brain called the dorsolateral prefrontal cortex, which is important in determining the feeling of fullness after eating, affects how much food a person eats and weight loss over 4 weeks. It will also compare weight changes in people who attend weight loss counseling sessions and those who do not over this period of time. Obese, non-diabetic people between 18 and 60 years of age who are in good health and who live in the Phoenix, AZ, metropolitan area are eligible for this study. Candidates must have a body mass index of 35 kg/m(2) or more and weigh less than 350 pounds. Participants are admitted to the NIH inpatient unit in Phoenix for the first 9 days of the study for tests, which include meal tests to determine eating behaviors and caloric intake, blood and urine tests, glucose tolerance test, weight measurement, psychological assessments and DEXA scan to measure body fat. For 3 of the days, they will be asked to eat all of their food from automated vending machines. Some subjects receive transcranial direct current stimulation (TDCS). For this procedure, electrodes that conduct electricity are placed on the head and arm and the current is turned on for 40 minutes. Some tingling may be felt under the electrodes. Other subjects receive sham TDCS, with the current turned on only very briefly. After the evaluations, subjects are discharged home from the NIH unit and instructed to eat 25 percent fewer calories than they consumed while on a weight maintenance diet the first 3 days of their inpatient stay. They maintain the lower calorie diet at home for 4 weeks. During this period they come to the NIH unit 3 days a week to receive either real or sham TDCS.

In our studies of brain function examining areas related to hunger and fullness, a part of the brain called the left dorsolateral prefrontal cortex (DLPFC) was found to be less active in obese versus lean individuals following a meal. Furthermore, in women who have lost and maintained weight loss, the activity in this area following a meal is similar to that of lean women, suggesting that the activity in this area may improve with weight loss. Two recent studies have demonstrated a lack of increase in food craving following non-invasive brain stimulation to the left DLPFC when compared to a sham control group that did not receive brain stimulation. The aim of our protocol is to investigate the effectiveness of one type of noninvasive brain stimulation technique, transcranial direct current stimulation (tDCS) on food intake in significantly overweight (BMI \>= 30 kg/m\^2) individuals. In study 1, we enrolled individuals who previously participated in this study and examined how anodal (active) stimulation or sham (no stimulation) to the left DLPFC compared to their previous stimulation condition in terms of both weight loss and food intake. The aim of Study 2 was to compare active versus sham anodal left DLPFC stimulation in a new group of volunteers. Study 3 will be a 9-week double-blind parallel outpatient study where volunteers will come to the Clinical Research Unit 3x per week and be randomized to receive either active tDCS or "no stimulation" (sham) to the left DLPFC for stimulation sessions while being asked to follow diet that is a 25% reduction from their calculated weight maintenance calories. The primary outcome measurement will be total food (kcal) intake during a snack food taste test and weight change. Volunteers will also undergo 4 sessions of brain imaging (called functional MRI) to help us understand how the stimulation is working. Participants will also be asked to come back to the Unit after 6 months and 1 year for weight measurements. We will also examine appetitive hormones, neurocognitive and behavioral factors, which might also mediate potential changes in food intake and weight following tDCS to the left DLPFC. Positive findings from this study could demonstrate the utility of a novel and safe treatment for severe obesity. Future studies could include longer clinical trials of tDCS with extended follow-up durations.