Commentary by Marci E. Gluck, PhD and Brian Harris Kopell, MD
“Clinically, the results imply that obesity might be related to neurological differences, particularly in the LDLPFC, which is the brain region that affects reward processing and executive functions such as planning and decision making,” said lead author Marci E. Gluck, PhD, Research Clinical Psychologist at the Phoenix Epidemiology & Clinical Research Branch of the National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, USA. “This new knowledge could inform treatment options. Currently, there aren’t any standardized treatments to help improve brain functioning, but several types of new interventions are being studied, and we hope that our findings encourage further research in brain-based intervention for obesity and weight loss.”
“Previous studies from our laboratory had found lower levels of activation in the LDLPFC after a meal in obese compared to lean people,” Dr. Gluck explained. “We used that information to hypothesize that the activating the LDLPFC in people who are obese might improve their ability to make healthy food choices, and as a result, lose weight.”
“This study gives us insight into what is going on in the morbidity obese brain in terms of what role the brain plays in maintaining poor eating behaviors,” commented Brian Harris Kopell, MD, Director of the Center for Neuromodulation at Mount Sinai Health System, New York, NY. “It appears that transcranial direct current stimulation (tDCS) to the DLPFC improved impulse control in this study.”
Randomized Controlled Study
The study involved 9 men and women (ages 18 to 60 years) with obesity who resided in the Branch’s clinical research unit on 2 separate visits, each for 9 days. On each visit, the participants ate a weight-maintaining diet for 5 days followed by 3 days of treatment with tDCS or sham tDCS given for 40 minutes per session. Participants then ate and drank as much as they wanted from computerized vending machines.
The four people who received sham stimulation during both visits consumed the same number of calories from the vending machines on each visit and did not lose weight. In contrast, the 5 people who received inactive stimulation on the first visit, and active tDCS at the brain target on the second visit, consumed an average of 700 fewer calories (P=0.07) and lost an average of 0.8 pounds on the second visit (P=0.009).
Connection Between Brain Activity and Eating Behavior
“Obesity is a complicated issue that must be examined from many different angles,” Dr. Gluck concluded. “By providing context on the connection between brain activity and eating behavior, our study has helped us understand why people who are obese often struggle to make healthy food choices. The findings offer evidence that tDCS may one day give people who are obese an additional strategy to achieve a healthy weight.”
Is Neuromodulation a Viable Solution for the Obesity Epidemic?
“Do I believe that there are ways to modulate brain function to change the way we eat? Absolutely. The brain is the driver in this whole process. However, I do not think that neuromodulation is how we are going to treat the obesity problem globally,” said Dr. Kopell, who is a member of the International Neuromodulation Society. He added that the obesity epidemic is caused by a number of complex issues, including food sources and lack of education on proper nutrition among both patients and health care professionals.
Dr. Kopell said he could envision neuromodulation being used in select cases, such as in the course of rehabilitating a severely morbidly obese patient to temporarily bolster the patient’s impulse control while simultaneously educating the patient on exercise and nutrition. He noted that when people eat high-sugar foods, the brain is rewired to crave those foods much in the way that the brain is rewired with repeated use of heroin. Use of tDCS theoretically may block the impulse to eat high-sugar foods and allow the brain to again rewire back to its normal state in terms of sugar craving, he said.
“We currently have a larger study in progress examining food intake and weight loss using anodal (active) compared to sham (placebo) stimulation in people with obesity,” Dr. Gluck told EndocrineWeb. “We also plan to explore changes in executive functions before and after stimulation by using computerized neuropsychological tests. The device used to administer tDCS is portable, and if future studies show promising results, this technique could be used outside of a medical setting. Just as the light box became a home intervention for treating seasonal affective disorder, tDCS potentially could be used at home to treat weight-related disorders, in combination with regular physical activity and healthy eating.”
“As the duration of treatment effect is unclear, future studies should investigate the timing of the treatment (fasting vs. fed) and the timing of its effects,” Dr. Gluck said. “Based on what we know now, we believe the effects are short-term. In our larger study, we are testing the effects of administering tDCS 3 times per week for 4 weeks. We will examine the impact on weight and food intake over that longer period to determine if the effects of brain stimulation are cumulative.”
November 11, 2015
Gluck ME, Alonso-Alonso M, Piaggi P, et al. Neuromodulation targeted to the prefrontal cortex induces changes in energy intake and weight loss in obesity. Obesity (Silver Spring). 2015;23(11):2149-2156.