A randomized controlled trial of noninvasive neuromodulation of the prefrontal cortex in women with obesity: Analysis of 1-year Follow-up
Priscila Giacomo Fassini 1,3, Sai Krupa Das 2, Vivian Marques Miguel Suen 3, Greta Magerowski 1, Júlio Sérgio Marchini 3, Miguel Alonso-Alonso 1.
- Laboratory of Bariatric and Nutritional Neuroscience, Center for the Study of Nutrition Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
- Energy Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA
- Department of Internal Medicine, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP
OBJECTIVE: Transcranial direct current stimulation (tDCS) targeted to the dorsolateral prefrontal cortex (DLPFC) has been investigated to modulate brain activity in studies in the field of obesity. However, evidence to date is limited to short-term studies. Here, we investigated the effects of DLPFC-targeted tDCS in young women with obesity over a period of 12 months.
METHODS: Randomized, double-blind, sham-controlled clinical trial assessing 38 women with obesity (ClinicalTrials.gov NCT02953353). Participants underwent an intervention consisting of: Phase I - target engagement (immediate effects of tDCS on working memory performance), Phase II - tDCS only (10 sessions, 2 weeks), Phase III - tDCS + hypocaloric diet: (6 sessions, 30% energy intake reduction, 2 weeks, inpatient), and Phase IV – follow-up of 12 months. Changes in body weight were evaluated at the end of each phase. Data were analyzed as linear mixed models (P˂0.05).
RESULTS: There was a 3% reduction in body weight at the end of the intervention, with no significant difference between groups. The active group regained weight at 6-month follow-up, compared with sham, and at 12-month follow-up, presented a 3% increase in body weight, compared to baseline. Genetic analysis indicated that the subgroup of Met non-carriers of Catechol-O-methyltransferase (COMT) accounted for this paradoxical response in the active group, demonstrating 19% weight gain at 12 months.
CONCLUSIONS: Our study suggests that prefrontal tDCS did not facilitate weight loss in young women with obesity. Genotype differences impacting dopamine availability could explain a paradoxical effect in this population. Further investigation is needed to confirm these findings.
KEYWORDS: Transcranial direct current stimulation, dorsolateral prefrontal cortex, obesity
ACKNOWLEDGMENTS: The authors thank all the volunteers for their participation in this study and the financial support from São Paulo Research Foundation (FAPESP) and Foundation for Support to Teaching, Research and Assistance (FAEPA) of the Clinical Hospital of Ribeirão Preto Medical School, University of São Paulo.
FUNDING/FINANCIAL SUPPORT: FAPESP (2016/04766-6, 2016/10785-3 and 2016/14592-5) and FAEPA (27/2018).