Transcranial Direct Current Stimulation (tDCS) with Cognitive Training to Reduce Impulsivity and Weight in Veterans with Obesity: A Clinical Trial

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Impulsivity has been implicated in refractory obesity in bariatric and non-bariatric subjects (Sutin 2011, Filbey 2017, Gunstad 2017, Galioto 2016, Benard 2017). A healthy prefrontal cortex (PFC) may mitigate excess impulsivity effects on appetite regulation by providing critical executive function as a gate-keeper. Galioto et al found that executive function predicts weight loss success in structured medical weight loss programs (Galioto 2016). Given this background, improving prefrontal executive function to mitigate impulsivity would be valuable in obesity treatment. Cognitive training for improvement of executive function has not shown sufficient therapeutic promise. Similarly, transcranial direct current stimulation (tDCS), a noninvasive neuromodulation modality, aimed at the PFC has been shown to be safe and well tolerated but not sufficiently effective as monotherapy. Combining prefrontal neuromodulation with cognitive training may be the novel, effective way forward for prefrontal neuromodulation as obesity therapy. Together, the two modalities enhanced executive function in non-obese subjects with executive function deficits in studies done by members of our team (Gilmore 2018). Thirty subjects with a clinical history of impulsive behavior were recruited for a sham-controlled protocol coupling the balloon analog risk task, a decision-making test, with five consecutive days of 25-minute tDCS treatments in which a 2-mA constant current was delivered over the dorsolateral PFC, anode over right PFC and cathode over the left PFC. Active tDCS stimulation coupled with cognitive training improved Balloon Analog Risk Task performance and reduced impulsivity on the Barratt Impulsiveness Scale. Reduction in risky decision making generalized to a second risk-related decision-making task, the Risk Task, which had not been utilized during the stimulated training sessions. Reduction in risky decision making persisted at the final two month follow up visit. This evidence supports our hypothesis that tDCS coupled with brain training can enhance executive function and improve clinical outcomes in individuals who suffer from impulsivity-related conditions. Neuroplasticity-based interventions such as this may provide novel treatment approaches to the challenging clinical problem of obesity. We have assembled a team of investigators with combined obesity and neuromodulation expertise to conduct a randomized double-blind trial of active vs. sham tDCS combined with cognitive training in subjects with obesity who report out-of-control eating and are enrolling in a structured group lifestyle coaching program. We will determine if tDCS coupled with cognitive training decreases impulsivity in these individuals with obesity. Our second aim is to evaluate whether tDCS coupled with executive function training enhances weight loss.