JMIR Publications

ABSTRACT

Background:

Metabolic and bariatric surgery (MBS) is presently the most effective and durable obesity treatment. However, there is substantial heterogeneity in weight and health outcomes that can be partially attributed to variability in appetite and eating regulation. People with a strong desire to eat in response to the reward of palatable foods are more likely to overeat and experience suboptimal outcomes after MBS. This at-risk subgroup may benefit from repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, that shows promise for reducing cravings and consumption of addictive drugs and food. To date, no study has evaluated rTMS in the context of MBS or how rTMS impacts the reinforcing value of food and brain reward processing among people who find food highly reinforcing and are prone to overeating.

Objective:

The goal of the RESTRAIN (tRanscranial MagnEtic STimulation to Reduce RelAtive ReinforcINg Value of Food) study is to perform an initial test of rTMS on the relative-reinforcing value of food (RRV: reinforcing value of palatable food relative to money) among adult patients who are pursuing MBS and report high levels of food reinforcement. Using a within-participants, sham-controlled crossover design, we aim to compare the active and sham rTMS conditions on pre- to post-test changes in RRV (primary objective) and neural modulation of reward, measured by electroencephalography (EEG) (secondary objective).

Methods:

Participants (n=10) pursuing MBS attend two study sessions separated by a 1- to 4-week washout period. Participants are randomized to active rTMS on one day and sham rTMS on the other day using a counterbalanced schedule. For both sessions, participants arrive fasted in the morning to the research center where they consume a standardized breakfast before being assessed on the RRV and reward tasks with EEG before and after rTMS of the left dorsolateral prefrontal cortex (dlPFC).

Results:

Recruitment and data collection began in December 2022. As of July 2023, 29 patients were recruited and screened, 17 patients screened positive, 9 patients were enrolled, 3 withdrew, and 6 patients have completed the protocol.

Conclusions:

The RESTRAIN study is the first to conduct an initial test of whether rTMS can target neural reward circuits to reduce behavioral (RRV) and neural (EEG) measures of food reward in MBS patients who have high hedonic hunger and susceptibility to overeating. If successful, results would provide rationale for a fully-powered trial to examine whether rTMS-related changes in food reinforcement translate into healthier eating patterns and improved weight and metabolic outcomes after MBS. If results do not support hypotheses, we will continue this line of research to evaluate whether additional rTMS sessions and pulses and/or different stimulus locations can produce clinically meaningful changes in food reinforcement in this patient population. Clinical Trial: clinicaltrials.gov NCT05522803