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

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.