RESUMO
BACKGROUND/OBJECTIVES: Obesity is associated with reduced neurocognitive performance. Individuals with obesity show decreased activation in the left dorsolateral prefrontal cortex (DLPFC), a key brain region relevant to the regulation of eating behavior. Transcranial direct current stimulation (tDCS) has emerged as a potential technique to correct these abnormalities. However, there is limited information to date, particularly in clinical settings and regarding long-term effects of tDCS. This study aimed to investigate the effects of DLPFC-targeted tDCS in young women with obesity. SUBJECT/METHODS: Randomized, double-blind, sham-controlled parallel-design clinical trial conducted in 38 women, aged 20-40 years, with BMI 30-35 kg/m2. STUDY DESIGN: Phase I: target engagement (immediate effects of tDCS on working memory performance), Phase II: tDCS only (ten sessions, 2 weeks), Phase III: tDCS + hypocaloric diet (six sessions, 30% energy intake reduction, 2 weeks, inpatient), Phase IV: follow-up at 1, 3, and 6 months. PRIMARY OUTCOME: change in body weight. SECONDARY OUTCOMES: change in eating behavior and appetite. Additional analyses: effect of Catechol-O-methyl transferase (COMT) gene variability. Data were analyzed as linear mixed models. RESULTS: There was no group difference in change in body weight during the tDCS intervention. At follow-up, the active group lost less weight than the sham group. In addition, the active group regained weight at 6-month follow-up, compared with sham. Genetic analysis indicated that COMT Met noncarriers were the subgroup that accounted for this paradoxical response in the active group. CONCLUSION: Our results suggest that in young women with class I obesity, tDCS targeted to the DLPFC does not facilitate weight loss. Indeed, we found indications that tDCS could have a paradoxical effect in this population, possibly connected with individual differences in dopamine availability. Future studies are needed to confirm these findings.
