The effect of expectation on transcranial direct current stimulation (tDCS) to suppress food craving and eating in individuals with overweight and obesity.

Transcranial direct current stimulation (tDCS) is a neuromodulation technique with potential to treat eating disorders and obesity. As for any potential treatment, it is important to assess the degree to which expectation effects contribute to its reported efficacy. This study assessed the effect of tDCS on amount of food craving and eating while tightly controlling treatment expectation. N = 74 adults with overweight or obesity were informed of the known effects of tDCS to suppress craving and eating. Once electrodes were on the head, half of the participants were told they were receiving real, and the other half sham tDCS. Within these groups, approximately half actually received real and the other half sham tDCS. Stimulation parameters used were those previously found to reduce craving and eating, including in our lab: 2 mA, anode right/cathode left targeting the dorsolateral prefrontal cortex for 20 min (real), or only for the first and last minute (sham). Analyses controlled for demographics, hunger, trait impulsiveness, eating motives, dieting, binge eating, suggestibility, and baseline craving and eating. Participants told they were receiving real tDCS craved and ate less than participants told they were receiving sham tDCS (both p < 0.01), regardless of tDCS condition administered. There was no main effect of real vs. sham tDCS on craving or eating or an interaction between tDCS condition and expectation. The scientific validation of tDCS as a treatment for eating-related conditions hinges on controlling for the powerful effects of expectation. This can include the type of information provided on consent forms and participants' ability to guess real from sham conditions.

Baseline motives for eating palatable food: racial differences and preliminary utility in predicting weight loss.

PURPOSE: Behavioral predictors of weight-loss program (WLP) outcomes are needed and important because they can be modified. Eating calorie-dense palatable foods (PFs) outside of hunger contributes to obesity. This study assessed if habitual motives to consume PFs could predict weight-loss outcomes. METHODS: N = 171 Black and N = 141 White adults in a reduced-calorie program completed the Palatable Eating Motives Scale (PEMS). Body weight and body mass index (BMI) lost after 3 and 6 months were analyzed controlling for initial BMI and demographics. Greater PEMS motive scores meant more frequent habitual intake of PFs for that motive. RESULTS: Whites vs. Blacks had higher scores on most of the PEMS motives: Social, Coping, and Reward Enhancement. In Whites at 3 months, greater Reward Enhancement scores and initial BMI predicted more BMI loss (p < 0.05). At 6 months, greater Reward Enhancement and lower Conformity scores predicted more weight (p < 0.05) and BMI loss (Conformity: p < 0.05; Reward Enhancement: p = 0.05). PEMS motives did not predict outcomes for Blacks. CONCLUSION: The results provide preliminary evidence for the PEMS to predict WLP outcomes. White patients who eat PFs primarily for their rewarding properties and less to conform should fare better in Lifestyle programs while group or family-based interventions may be more efficacious when conformity is the main motive. Lower motive scores among Blacks suggest that eating PFs outside of hunger may go unrecognized or underreported and warrants further investigation. The findings highlight the motive-based heterogeneity of obesity and how it may be used to predict outcomes and customize interventions to improve WLP outcomes. LEVEL OF EVIDENCE: Level IV, multiple time series.

The critical role of cognitive-based trait differences in transcranial direct current stimulation (tDCS) suppression of food craving and eating in frank obesity.

Obesity remains a major public health concern and novel treatments are needed. Transcranial direct current stimulation (tDCS) is a neuromodulation technique shown to reduce food craving and consumption, especially when targeting the dorsolateral prefrontal cortex (DLPFC) with a right anode/left cathode electrode montage. Despite the implications to treat frank (non-bingeeating) obesity, no study has tested the right anode/left cathode montage in this population. Additionally, most tDCS appetite studies have not controlled for differences in traits under DLPFC control that may influence how well one responds to tDCS. Hence, N = 18 (10F/8M) adults with frank obesity completed the Dutch Eating Behavior Questionnaire-Restraint and Barratt Impulsiveness Scale, and received 20 min of 2 mA active tDCS and control tDCS session. Craving and eating was assessed at both sessions with a food photo "wanting" test and in-lab measures of total, preferred, and less-preferred kilocalories consumed of three highly palatable snack foods. While main effects of tDCS vs. control were not found, significant differences emerged when trait scores were controlled. tDCS reduced food craving in females with lower attention-type impulsiveness (p = 0.047), reduced preferred-food consumption in males with lower intent to restrict calories (p = 0.024), and reduced total food consumption in males with higher non-planning-type impulsiveness (p = 0.009) compared to control tDCS. This is the first study to find significant reductions in food craving and consumption in a sample with frank obesity using the most popular tDCS montage in appetite studies. The results also highlight the cognitive-based heterogeneity of individuals with obesity and the importance of considering these differences when evaluating the efficacy of DLPFC-targeted tDCS in future studies aimed at treating obesity.

Effects of transcranial direct current stimulation (tDCS) on binge eating disorder.

OBJECTIVE: To investigate the effect of transcranial direct current stimulation (tDCS) on food craving, intake, binge eating desire, and binge eating frequency in individuals with binge eating disorder (BED). METHOD: N = 30 adults with BED or subthreshold BED received a 20-min 2 milliampere (mA) session of tDCS targeting the dorsolateral prefrontal cortex (DLPFC; anode right/cathode left) and a sham session. Food image ratings assessed food craving, a laboratory eating test assessed food intake, and an electronic diary recorded binge variables. RESULTS: tDCS versus sham decreased craving for sweets, savory proteins, and an all-foods category, with strongest reductions in men (p < 0.05). tDCS also decreased total and preferred food intake by 11 and 17.5%, regardless of sex (p < 0.05), and reduced desire to binge eat in men on the day of real tDCS administration (p < 0.05). The reductions in craving and food intake were predicted by eating less frequently for reward motives, and greater intent to restrict calories, respectively. DISCUSSION: This proof of concept study is the first to find ameliorating effects of tDCS in BED. Stimulation of the right DLPFC suggests that enhanced cognitive control and/or decreased need for reward may be possible functional mechanisms. The results support investigation of repeated tDCS as a safe and noninvasive treatment adjunct for BED. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2016; 49:930-936).

Eating tasty foods to cope, enhance reward, socialize or conform: What other psychological characteristics describe each of these motives?

Psychological characteristics associated with eating motives of the Palatable Eating Motives Scale (PEMS) were identified in 192 undergraduates. Coping was characterized by greater BMI, emotion-triggered eating, and eating concern and also by binge-eating and perceived stress reactivity in females. Reward Enhancement was characterized by greater BMI, anxiety- and depression-eating in females and by anger/frustration-eating in males. Conformity was strongly characterized by binge-eating and by failure-based stress and all eating disorder traits in females and by anger/frustration- and anxiety-eating in males. The sex-divergent patterns of these traits across PEMS motives highlight the heterogeneity of hedonic eating. The traits may also be maintaining the motives, hence adresseing them should improve treatments for obesity, binge-eating, and foster healthier coping, reward, and psychosocial interactions.

Real-time sampling of reasons for hedonic food consumption: further validation of the Palatable Eating Motives Scale.

Highly palatable foods play a salient role in obesity and binge-eating, and if habitually eaten to deal with intrinsic and extrinsic factors unrelated to metabolic need, may compromise adaptive coping and interpersonal skills. This study used event sampling methodology (ESM) to examine whether individuals who report eating palatable foods primarily to cope, to enhance reward, to be social, or to conform, as measured by the Palatable Eating Motives Scale (PEMS), actually eat these foods primarily for the motive(s) they report on the PEMS. Secondly this study examined if the previously reported ability of the PEMS Coping motive to predict BMI would replicate if the real-time (ESM-reported) coping motive was used to predict BMI. A total of 1691 palatable eating events were collected from 169 college students over 4 days. Each event included the day, time, and types of tasty foods or drinks consumed followed by a survey that included an abbreviated version of the PEMS, hunger as an additional possible motive, and a question assessing general perceived stress during the eating event. Two-levels mixed modeling confirmed that ESM-reported motives correlated most strongly with their respective PEMS motives and that all were negatively associated with eating for hunger. While stress surrounding the eating event was strongly associated with the ESM-coping motive, its inclusion in the model as a predictor of this motive did not abolish the significant association between ESM and PEMS Coping scores. Regression models confirmed that scores on the ESM-coping motive predicted BMI. These findings provide ecological validity for the PEMS to identify true-to-life motives for consuming palatable foods. This further adds to the utility of the PEMS in individualizing, and hence improving, treatment strategies for obesity, binge-eating, dietary nutrition, coping, reward acquisition, and psychosocial skills.