Single-Session Transcranial Direct Current Stimulation Temporarily Improves Symptoms, Mood, and Self-Regulatory Control in Bulimia Nervosa: A Randomised Controlled Trial

Bulimia nervosa and treatment-related disparities: a review

Introduction

Bulimia nervosa (BN) is a type of eating disorder disease usually manifesting between adolescence and early adulthood with 12 as median age of onset. BN is characterized by individuals' episodes of excessive eating of food followed by engaging in unusual compensatory behaviors to control weight gain in BN. Approximately 94% of those with BN never seek or delay treatment. While there are available treatments, some populations do not have access. Left untreated, BN can become severe and lead to other serious comorbidities. This study is a review of randomized controlled trials to explore available treatments and related treatment disparities. The objective of this review was to identify differences among treatment modalities of BN and aide in the further treatment and research of bulimia nervosa.

Methods

This study followed narrative overview guidelines to review BN treatment studies published between 2010 and 2021. The authors used PubMed and PsychInfo databases to search for articles meeting the inclusion criteria. Search terms included phrases such as, BN treatment, BN and clinical trials, and BN and randomized clinical trials.

Results

Most of the reviewed studies had their sample sizes between 80 and 100% female with age range between 18 and 60 years old. Sample sizes were mostly between 80 and 100% white. Treatment practices included both pharmacological and psychosocial interventions, such as cognitive behavioral therapy (CBT) and limited motivational interviewing (MI). Most studies were in outpatient settings.

Conclusion

Reviewed research shows that certain populations face disparities in BN treatment. Generally, individuals older than 60, males and racial minorities are excluded from research. Researchers and practitioners need to include these vulnerable groups to improve BN treatment-related disparities.

The relationship between frontal alpha asymmetry and behavioral and brain activity indices of reactive inhibitory control

Reactive inhibitory control plays an important role in phenotype of different diseases/different phases of a disease. One candidate electrophysiological marker of inhibitory control is frontal alpha asymmetry (FAA). FAA reflects the relative difference in contralateral frontal brain activity. However, the relationship between FAA and potential behavioral/brain activity indices of reactive inhibitory control is not yet clear. We assessed the relationship between resting-state FAA and indicators of reactive inhibitory control. Additionally, we investigated the effect of modulation of FAA via transcranial direct current stimulation (tDCS). We implemented a randomized sham-controlled design with 65 healthy humans (Mage = 23.93, SDage = 6.08; 46 female). Before and after 2-mA anodal tDCS of the right frontal site (with the cathode at the contralateral site) for 20 min, we collected EEG data and reactive inhibitory performance in neutral and food-reward conditions, using the stop signal task (SST). There was no support for the effect of tDCS on FAA or any indices of reactive inhibitory control. Our correlation analysis revealed an association between inhibitory brain activity in the food-reward condition and (pre-tDCS) asymmetry. Higher right relative to left frontal brain activity was correlated with reduced early-onset inhibitory activity and, in contrast, linked with higher late-onset inhibitory control in the food-reward condition. Similarly, event-related potential analyses showed reduced early-onset and enhanced late-onset inhibitory brain activity over time, particularly in the food-reward condition. These results suggest that there can be a dissociation regarding the lateralization of frontal brain activity and early- and late-onset inhibitory brain activity.NEW & NOTEWORTHY This research reveals dissociation between baseline frontal alpha asymmetry and the timing of reactive inhibitory brain activities in food-reward contexts. Whereas inhibitory control performance decreases over time in a stop signal task, electrophysiological indices show reduced early- and heightened late-onset inhibitory brain activity, especially in the reward condition. Additionally, greater right frontal activity correlates with reduced early-onset and increased late-onset inhibitory brain activity.

Efficacy of Transcranial Direct Current Stimulation for Controlling of Food Craving in Subjects With Overweight or Obesity: A Pilot Study

OBJECTIVE

We aim to explore the effects of transcranial direct current stimulation (tDCS) on food craving improvement and changes in brain function associated with craving by conducting a total of 10 sessions of tDCS over a period of 2 weeks on overweight and obese subjects.

METHODS

A total of 15 patients who were overweight or obese (body mass index [BMI] ≥23 kg/m2) were included. Weight, BMI, neuropsychological variables, and food craving-related variables were assessed. We measured absolute and relative power in 19 channels and analyzed quantitative electroencephalography (qEEG) according to the following frequency ranges: delta (1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-25 Hz), high beta (25-30 Hz), and gamma (30-80 Hz).

RESULTS

After the application of tDCS, there was no significant reduction observed in weight and BMI. However, all measures related to food and eating showed a decrease in the intensity of cravings, and there was also a significant reduction in depression, anxiety, and perceived stress. In qEEG analysis, an increase in theta waves was observed in the left frontal area (F7 and F3), an increase in alpha waves in the right parietal area (P4), and a decrease in beta waves in the frontal area (FP2) and occipital area (O1).

CONCLUSION

This study confirmed the beneficial effects of tDCS on food craving regulation in overweight or obese individuals and observed improved scores in psychological factors such as depression and anxiety. Furthermore, neurophysiological changes related to food craving were observed using qEEG.

No effect of prefrontal transcranial direct current stimulation (tDCS) on food craving, food reward and subjective appetite in females displaying mild-to-moderate binge-type behaviour

Previous work suggests there may be an effect of transcranial direct current stimulation (tDCS) on appetite control in people at risk of overconsumption, however findings are inconsistent. This study aimed to further understand the potential eating behaviour trait-dependent effect of tDCS, specifically in those with binge-type behaviour. Seventeen females (23 ± 7 years, 25.4 ± 3.8 kg m-2) with mild-to-moderate binge eating behaviour completed two sessions of double-blind, randomised and counterbalanced anodal and sham tDCS applied over the right dorsolateral prefrontal cortex at 2.0 mA for 20 min. Subjective appetite visual analogue scales (VAS), the Food Craving Questionnaire-State (FCQ-S), and Leeds Food Preference Questionnaire (LFPQ) were completed pre- and post-tDCS. Participants then consumed a fixed-energy meal, followed by the VAS, FCQ-S and LFPQ. No difference between pre- and post-tDCS scores were found across fullness (p = 0.275, BF10 = 0.040), prospective consumption (p = 0.127, BF10 = 0.063), desire to eat (p = 0.247, BF10 = 0.054) or FCQ-S measures (p = 0.918, BF10 = 0.040) when comparing active and sham protocols. Only explicit liking and wanting for high-fat sweet foods were significantly different between conditions, with increased scores following active tDCS. When controlling for baseline hunger, the significant differences were removed (p = 0.138 to 0.161, BF10 = 0.810 to 1.074). The present data does not support the eating behaviour trait dependency of tDCS in a specific cohort of female participants with mild-to-moderate binge eating scores, and results align with those from individuals with healthy trait scores. This suggests participants with sub-clinical binge eating behaviour do not respond to tDCS. Future work should further explore effects in clinical and sub-clinical populations displaying susceptibility to overconsumption and weight gain.

Transcranial direct current stimulation (tDCS) over the orbitofrontal cortex reduces delay discounting

Delay discounting (DD) is a quantifiable psychological phenomenon that regulates decision-making. Nevertheless, the neural substrates of DD and its relationship with other cognitive domains are not well understood. The orbitofrontal cortex (OFC) is a potential candidate for supporting the expression of DD, but due to its wide involvement in several psychological functions and neural networks, its central role remains elusive. In this study, healthy subjects underwent transcranial direct current stimulation (tDCS) while performing an intertemporal choice task for the quantification of DD and a working memory task. To selectively engage the OFC, two electrode configurations have been tested, namely, anodal Fp1-cathodal Fp2 and cathodal Fp1-anodal Fp2. Our results show that stimulation of the OFC reduces DD, independently from electrode configuration. In addition, no relationship was found between DD measures and either working memory performance or baseline impulsivity assessed through established tests. Our work will direct future investigations aimed at unveiling the specific neural mechanisms underlying the involvement of the OFC in DD, and at testing the efficacy of OFC tDCS in reducing DD in psychological conditions where this phenomenon has been strongly implicated, such as addiction and eating disorders.

Pharmacotherapy, alternative and adjunctive therapies for eating disorders: findings from a rapid review

BACKGROUND

The current review broadly summarises the evidence base for pharmacotherapies and adjunctive and alternative therapies in the treatment of eating disorders and disordered eating.

METHODS

This paper forms part of a Rapid Review series examining the evidence base in the field of eating disorders. This was conducted to inform the Australian National Eating Disorder Research and Translation Strategy 2021-2030. ScienceDirect, PubMed and Ovid/Medline were searched for included studies published between 2009 and 2021 in English. High-level evidence such as meta-analyses, large population studies and randomised control trials were prioritised, and grey literature excluded. Data from included studies relating to pharmacotherapy, and to adjunctive and alternative therapies in eating disorders, were synthesised and disseminated in the current review.

RESULTS

A total of 121 studies were identified, relating to pharmacotherapy (n = 90), adjunctive therapies (n = 21) and alternative therapies (n = 22). Some of the identified studies involved combinations of the above (e.g. adjunctive pharmacotherapy). Evidence of efficacy of interventions across all three categories was very limited with few relevant high quality clinical trials. There was a particular scarcity of evidence around effective treatments for anorexia nervosa (AN). With treatment of bulimia nervosa (BN), fluoxetine has exhibited some efficacy leading to regulatory approval in some countries. With binge eating disorder (BED), recent evidence supports the use of lisdexamfetamine. Neurostimulation interventions show some emerging efficacy in the treatment of AN, BN and BED but some, such as deep brain stimulation can be highly invasive.

CONCLUSION

Despite widespread use of medications, this Rapid Review has identified a lack of effective medications and adjunctive and alternative therapies in the treatment of EDs. An intensification of high-quality clinical trial activity and drug discovery innovation are required to better assist patients suffering from EDs.

Central Regulation of Eating Behaviors in Humans: Evidence from Functional Neuroimaging Studies

Neuroimaging has great potential to provide insight into the neural response to food stimuli. Remarkable advances have been made in understanding the neural activity underlying food perception, not only in normal eating but also in obesity, eating disorders, and disorders of gut-brain interaction in recent decades. In addition to the abnormal brain function in patients with eating disorders compared to healthy controls, new therapies, such as neurofeedback and neurostimulation techniques, have been developed that target the malfunctioning brain regions in patients with eating disorders based on the results of neuroimaging studies. In this review, we present an overview of early and more recent research on the central processing and regulation of eating behavior in healthy and patient populations. In order to better understand the relationship between the gut and the brain as well as the neural mechanisms underlying abnormal ingestive behaviors, we also provide suggestions for future directions to enhance our current methods used in food-related neuroimaging studies.

State-specific alterations in the neural computations underlying inhibitory control in women remitted from bulimia nervosa

The neurocomputational processes underlying bulimia nervosa and its primary symptoms, out-of-control overeating and purging, are poorly understood. Research suggests that the brains of healthy individuals form a dynamic internal model to predict whether control is needed in each moment. This study tested the hypothesis that this computational process of inhibitory control is abnormally affected by metabolic state (being fasted or fed) in bulimia nervosa. A Bayesian ideal observer model was fit to behavioral data acquired from 22 women remitted from bulimia nervosa and 20 group-matched controls who completed a stop-signal task during two counterbalanced functional MRI sessions, one after a 16 h fast and one after a meal. This model estimates participants' trial-by-trial updating of the probability of a stop signal based on their experienced trial history. Neural analyses focused on control-related Bayesian prediction errors, which quantify the direction and degree of "surprise" an individual experiences on any given trial. Regardless of group, metabolic state did not affect behavioral performance on the task. However, metabolic state modulated group differences in neural activation. In the fed state, women remitted from bulimia nervosa had attenuated prediction-error-dependent activation in the left dorsal caudate. This fed-state activation was lower among women with more frequent past binge eating and self-induced vomiting. When they are in a fed state, individuals with bulimia nervosa may not effectively process unexpected information needed to engage inhibitory control. This may explain the difficulties these individuals have stopping eating after it begins.

Altered prefrontal activation during the inhibition of eating responses in women with bulimia nervosa

BACKGROUND

The sense of 'loss of control' (LOC), or a feeling of being unable to stop eating or control what or how much one is eating, is the most salient aspect of binge eating. However, the neural alterations that may contribute to this experience and eating behavior remain poorly understood.

METHODS

We used functional near-infrared spectroscopy (fNIRS) to measure activation in the prefrontal cortices of 23 women with bulimia nervosa (BN) and 23 healthy controls (HC) during two tasks: a novel go/no-go task requiring inhibition of eating responses, and a standard go/no-go task requiring inhibition of button-pressing responses.

RESULTS

Women with BN made more commission errors on both tasks. BN subgroups with the most severe LOC eating (n = 12) and those who felt most strongly that they binge ate during the task (n = 12) showed abnormally reduced bilateral ventromedial prefrontal cortex (vmPFC) and right ventrolateral prefrontal cortex (vlPFC) activation associated with eating-response inhibition. In the entire BN sample, lower eating-task activation in right vlPFC was related to more frequent and severe LOC eating, but no group differences in activation were detected on either task when this full sample was compared with HC. BN severity was unrelated to standard-task activation.

CONCLUSIONS

Results provide initial evidence that diminished PFC activation may directly contribute to more severe eating-specific control deficits in BN. Our findings support vmPFC and vlPFC dysfunction as promising treatment targets, and indicate that eating-specific tasks and fNIRS may be useful tools for identifying neural mechanisms underlying dysregulated eating.

Reduction of drive for thinness and body dissatisfaction in people with self-reported dysregulated eating behaviors after intermittent theta burst stimulation (iTBS) of the left dorsolateral prefrontal cortex

Aim

This study aimed to explore the effect of intermittent theta burst stimulation (iTBS) of the right and left dorsolateral prefrontal cortex (DLPFC) in people with self-reported dysregulated eating behaviors but without a diagnosis of eating disorders (EDs).

Methods

Participants were randomly divided into two equivalent groups according to the side (right or left) of the hemisphere to be stimulated and they were tested before and after a single iTBS session. Outcome measurements were scores on self-report questionnaires assessing psychological dimensions related to eating behaviors (EDI-3), anxiety (STAI-Y), and tonic electrodermal activity.

Results

The iTBS interfered with both psychological and neurophysiological measures. Significant variations of physiological arousal after iTBS of both the right and left DLPFC were witnessed by increased mean amplitude of non-specific skin conductance responses. With regard to the psychological measures, the iTBS on the left DLPFC significantly reduced the scores of the EDI-3 subscales drive for thinness and body dissatisfaction. Interestingly, these two scales are two of the three EDI-3 clinic scales (drive for thinness, body dissatisfaction, and bulimia) used as specific markers to assess the onset and/or maintenance of eating disorders.

Conclusion

Our results show that the left DLPFC iTBS has an impact on the psychological dimensions that are risk factors for the onset of eating disorders, suggesting that an altered hemispheric asymmetry similar to that encountered in clinical populations is present in normal subjects even in the absence of clinical symptoms.

Neural Correlates of Delay Discounting in the Light of Brain Imaging and Non-Invasive Brain Stimulation: What We Know and What Is Missed

In decision making, the subjective value of a reward declines with the delay to its receipt, describing a hyperbolic function. Although this phenomenon, referred to as delay discounting (DD), has been extensively characterized and reported in many animal species, still, little is known about the neuronal processes that support it. Here, after drawing a comprehensive portrait, we consider the latest neuroimaging and lesion studies, the outcomes of which often appear contradictory among comparable experimental settings. In the second part of the manuscript, we focus on a more recent and effective route of investigation: non-invasive brain stimulation (NIBS). We provide a comprehensive review of the available studies that applied transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) to affect subjects’ performance in DD tasks. The aim of our survey is not only to highlight the superiority of NIBS in investigating DD, but also to suggest targets for future experimental studies, since the regions considered in these studies represent only a fraction of the possible ones. In particular, we argue that, based on the available neurophysiological evidence from lesion and brain imaging studies, a very promising and underrepresented region for future neuromodulation studies investigating DD is the orbitofrontal cortex.

Non-invasive brain stimulation interventions for treating Clinical and Sub-clinical eating disorders: A meta-analysis of randomized controlled trials and nonrandomized studies

This meta-analysis examined the effects of noninvasive brain stimulation (NIBS) for treating eating disorders (EDs), evaluating the difference between repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). We identified 15 studies on EDs, including 9 RCTs (266 participants) and 6 one-arm trials (59 participants). The pooled effect sizes indicated that NIBS plays a positive role in improving the eating symptoms of ED patients. Although its long-term effects need to be further explored, this treatment has the potential to be an important supplement to conventional ED therapy.

Effective Transcranial Direct Current Stimulation Parameters for the Modulation of Eating Behavior: A Systematic Literature Review and Meta-Analysis

OBJECTIVE

This study aimed to consider the effect of differing transcranial direct current stimulation (tDCS) parameters on eating-related measures and how issues with experimental design (e.g., inadequate blinding) or parameters variation may drive equivocal effects.

METHODS

Literature searches were conducted across MEDLINE, PsycINFO, Scopus, and Science Direct. Studies using conventional sham-controlled tDCS to modify eating-related measures in adult human participants were included. A total of 1135 articles were identified and screened by two independent authors. Study quality was assessed using the Risk of Bias tool. Random-effects meta-analyses were performed, with subgroup analyses to determine differences between parameter sets.

RESULTS

We identified 28 eligible studies; 7 showed low risk of bias, with the remaining studies showing bias arising from issues implementing or reporting blinding protocols. Large variation in applied parameters was found, including montage, current intensity and density, participant and researcher blinding, and the use of online or offline tasks. The application of differing parameters seemed to alter the effects of tDCS on eating-related measures, particularly for current density ( g = -0.25 to 0.31), and when comparing single-session ( g = -0.08 to 0.01) versus multisession protocols ( g = -0.34 to -0.29). Some parameters result in null effects.

CONCLUSIONS

The absence of tDCS-mediated change in eating-related measures may be driven by variation in applied parameters. Consistent application of parameters that seem to be effective for modulating eating behavior is important for identifying the potential impact of tDCS. Using the findings of this review, we propose a series of parameters that researchers should apply in their work.

The physiological control of eating: signals, neurons, and networks

During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.

Modulating eating behavior with transcranial direct current stimulation (tDCS): A systematic literature review on the impact of eating behavior traits

Transcranial direct current stimulation (tDCS) is becoming an increasingly popular technique for altering eating behaviors. Recent research suggests a possible eating behavior trait-dependent effect of tDCS. However, studies recruit participant populations with heterogeneous trait characteristics, including "healthy" individuals who do not present with eating behavior traits suggesting susceptibility to overconsumption. The present review considers the effects of tDCS across eating-related measures and explores whether a trait-dependent effect is evident across the literature. A literature search identified 28 articles using sham-controlled tDCS to modify eating-related measures. Random effects meta-analyses were performed, with subgroup analyses to identify differences between "healthy" and trait groups. Trivial overall effects (g = -0.12 to 0.09) of active versus sham tDCS were found. Subgroup analyses showed a more consistent effect for trait groups, with small and moderate effect size (g = -1.03 to 0.60), suggesting tDCS is dependent on participants' eating behavior traits. Larger effect sizes were found for those displaying traits associated with study outcomes (e.g., heightened food cravings). "Healthy" individuals appear to be unresponsive to stimulation. Based on this meta data, future work should recruit those with eating behavior trait susceptibilities to overconsumption, focusing on those who present with traits associated with the outcome of interest.

Neuromodulation and Eating Disorders

PURPOSE OF REVIEW

We review recent evidence on the use of neuromodulation for treating eating disorders (EDs), including anorexia nervosa, bulimia nervosa and binge eating disorder. We evaluate studies on (a) modern non-invasive methods of brain stimulation, such as transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), (b) electroconvulsive therapy (ECT) and (c) more invasive techniques, including deep brain stimulation (DBS).

RECENT FINDINGS

Most reports on the clinical applications of neuromodulation in EDs are limited to case studies, case series and small clinical trials. The majority have focused on severe, enduring and hard-to-treat cases of AN. In this population, data suggest that both rTMS and DBS have therapeutic potential and are safe and acceptable. High-quality clinical trials in different ED populations are needed which investigate different stimulation methods, sites and parameters, the use of neuromodulation as stand-alone and/or adjunctive treatment, as well as the mechanisms of action.

Does concurrent self-administered transcranial direct current stimulation and attention bias modification training improve symptoms of binge eating disorder? Protocol for the TANDEM feasibility randomized controlled trial

BACKGROUND

Binge eating disorder (BED) is a common and disabling problem associated with impaired cognitive control. Preliminary studies show that brain-directed treatments, including transcranial direct current stimulation (tDCS) and attention bias modification training (ABMT), improve cognitive control and alleviate symptoms of BED. When combined, tDCS may enhance the effects of ABMT, and vice versa, thereby improving treatment outcomes.

METHODS

This protocol describes a feasibility single-blind randomized sham-controlled trial of concurrent self-administered tDCS and ABMT in adults with BED (The TANDEM Trial). Eighty adults with BED will be randomly assigned to one of four groups: ABMT with real or sham self-administered tDCS, ABMT only, or waiting list control. In the treatment arms, participants will complete 10-sessions of their allocated intervention over 2-3 weeks. Outcomes will be assessed at baseline (T0), immediately post treatment (T1), and 6 weeks after end of treatment (T2), and at comparable timepoints for participants in the waitlist control group. Feasibility will be evaluated by assessing recruitment/retention rates and blinding success. Acceptability will be assessed quantitatively via participant ratings and qualitatively via semi-structured interviews. Episodes of binge eating at follow-up will be the primary clinical outcome and rate ratios from Poisson regression will be reported. Secondary outcomes will assess changes in ED and general psychopathology, attention bias toward high calorie foods, and executive function.

DISCUSSION

It is hoped that data from the trial will contribute to the development of neurobiologically informed treatments for BED, provide insights into the potential use of at-home variants of tDCS, and inform the design of future large scale trials.

Participant Experiences of Transcranial Direct Current Stimulation (tDCS) as a Treatment for Antipsychotic Medication Induced Weight Gain

Background: Despite the growing number of studies on the use of non-invasive brain stimulation in people with schizophrenia, there is limited research on participant views of such treatment methods. Aim: Explore participant experiences and perceptions of transcranial direct current stimulation (tDCS). Methods: Twelve people with schizophrenia took part in semi-structured interviews after having completed 5 sessions of tDCS. Thematic analysis was used to identify codes and themes. Results: Five themes were identified: (1) motivation for study enrolment; (2) concerns about tDCS; (3) factors reducing the fear of tDCS; (4) experience of tDCS; (5) perceived effects of tDCS. Conclusions: The study provides insight into the perceptions and experiences of each individual. Participants were concerned about the safety of tDCS and associated it with invasive procedures such as electroconvulsive therapy and lobotomy. Educational materials and a good relationship with the researcher played an important role in reducing the fear of brain stimulation. All participants described tDCS as uncomfortable, however, agreed that unpleasant sensations only lasted for a short while (20 s-5 min). After the first session, participants no longer felt anxious about the remaining ones. Strategies to improve treatment experience and study recruitment have been identified.

Can we change binge eating behaviour by interventions addressing food-related impulsivity? A systematic review

BACKGROUND

An extensive amount of research has underlined the potential role of impulsivity in the development and maintenance of binge eating behaviour. Food-related impulsivity has particularly received attention given its close relationship with overeating and binge eating episodes. Besides the available evidence, our understanding regarding the effectiveness of treatment modalities for binge eating targeting impulsivity and related constructs (e.g., food craving, inhibitory control, and reward sensitivity) is limited. Thus, this systematic review aimed to investigate whether binge eating behaviour is changeable by interventions that are impulsivity-focused and food-related and whether one of these interventions is superior to the others.

METHOD

A search on PubMed and PsycINFO was performed for relevant articles published up to September 2020. Studies delivering food-related impulsivity treatment to individuals suffering from binge eating episodes and including a control condition without this treatment were investigated. Following the search, 15 studies meeting the eligibility criteria were analysed.

RESULTS

Analyses revealed that available impulsivity-focused approaches can be categorised as psychotherapy, pharmacotherapy, computer-assisted cognitive training, and direct neuromodulation interventions. Regarding their effectiveness, it appeared that all of these approaches might be promising to change food-related impulsivity in individuals with binge eating episodes, particularly to decrease binge eating symptoms. However, a superior intervention approach in this early state of evidence could not be determined, although food-related cue exposure, transcranial direct current stimulation, and the combination of several interventions seem fruitful.

CONCLUSION

Efforts to treat binge eating behaviour with interventions focusing on food-related impulsivity appear to be promising, particularly concerning binge eating frequency, and also for food craving and inhibitory control. Given limited research and varying methods, it was not possible to conclude whether one impulsivity-focused intervention can be considered superior to others.

Combined antisaccade task and transcranial direct current stimulation to increase response inhibition in binge eating disorder

Binge eating disorder (BED) is associated with deficient response inhibition. Malfunctioning response inhibition is linked to hypoactivation of the dorsolateral prefrontal cortex (dlPFC), where excitability could be increased by anodal transcranial direct current stimulation (tDCS). Response inhibition can be assessed using an antisaccade task which requires supressing a dominant response (i.e. saccade) towards a newly appearing picture in the visual field. We performed a double-blind, randomised, placebo-controlled proof-of-concept-study in which we combined a food-modified antisaccade task with tDCS in people with BED. We expected task learning and modulatory tDCS effects. Sixteen people were allocated to a 1 mA condition, 15 people to a 2 mA condition. Each participant underwent the food-modified antisaccade task at three measurement points: baseline without stimulation, anodal verum and sham stimulation at the right dlPFC in a crossover design. The error rate and the latencies of correct antisaccades decreased over time. No tDCS effect on the error rate could be observed. Compared to sham stimulation, 2 mA tDCS decreased the latencies of correct antisaccades, whereas 1 mA tDCS increased it. Self-reported binge eating episodes were reduced in the 2 mA condition, while there was no change in the 1 mA condition. Participants demonstrated increased response inhibition capacities by a task learning effect concerning the error rate and latencies of correct antisaccades over time as well as a nonlinear tDCS effect represented by ameliorated latencies in the 2 mA and impaired latencies in the 1 mA condition. The reduction of binge eating episodes might indicate a transfer effect to everyday life. Given that the reduction in binge eating was observed before tDCS administration, this effect could not be the result of neuromodulation. Randomized clinical trials are needed to fully understand this reduction, and to explore the efficacy of a combined antisaccade and tDCS training for BED.

[Transcranial direct current stimulation in neurology and psychiatry]

Transcranial direct current stimulation (tDCS) is a non-invasive method of modulating brain excitability by low intensity direct current. At present, there are numerous studies of tDCS application in various mental and neurological diseases. In this review, the data of tDCS efficiency in the treatment of different disorders are presented and the recommendations on using this method in clinical practice are given.

Clinicians' views on neuromodulation as a treatment for eating disorders: A qualitative study

BACKGROUND

Neuromodulation techniques, such as repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS), are emerging as promising treatment options in eating disorders (EDs). To date, the views of ED clinicians regarding these interventions have not been explored.

METHODS

Eighteen clinicians were recruited from a specialist ED Service in London, UK. Following a short educational presentation on rTMS, tDCS and DBS, they completed a semi-structured interview to explore their views on the use of these treatment options in EDs.

RESULTS

Clinician knowledge of neuromodulation techniques was low. They raised safety and ethical (particularly capacity to consent) concerns mainly with regard to DBS. Neuromodulation treatments were considered most appropriate as an adjunct to psychotherapy and for patients with severe, enduring illness (who had completed previous psychological treatments).

CONCLUSIONS

Improving clinicians' knowledge and understanding of neuromodulation is fundamental for bridging the gap between research and clinical work. This is especially so given the predominance of psychological theory and practice in the treatment of EDs.

tDCS as a treatment for anxiety and related cognitive deficits

INTRODUCTION

Anxiety is characterized by psychological, physiological, and cognitive complaints. Current treatments have significant limitations, and often overlook any potential benefits to common cognitive symptoms, notably attention and executive function issues. The current study aimed to investigate the use of transcranial direct current stimulation (tDCS) on both common anxiety symptoms and executive function abilities in a college aged sample.

METHOD

As this is one of the first large scale anxiety studies utilizing tDCS, participants were given a single session of tDCS (anodal, cathodal, or sham) for 20 min at 2 mA over the left dorsolateral prefrontal cortex (lDLPFC). Participants also completed a series of self-reported anxiety measures and measures of executive functioning (Rey-O Copy and Wisconsin Card Sorting Task).

RESULTS

While there were no differences in anxiety between tDCS groups, a trend was noted demonstrating better performance on Rey-O Copy for the cathodal group. Anxiety increased pre to post for all groups.

CONCLUSION

Overall, results suggest that while anodal stimulation of the lDLPFC may benefit cognitive abilities for this population, targeting psychological symptoms of anxiety likely requires stimulation over other cortex, possibly right DLPFC. Further, the use of tDCS, whether active or sham, may be distressing to patients.

The Effects of Non-invasive Brain Stimulation on Impulsivity in People with Mental Disorders: a Systematic Review and Explanatory Meta-Analysis

Impulsivity is a multi-faceted construct that underpins various mental health disorders. Impulsive behavior exacts a substantial health and economic burden, hence the importance of developing specific interventions to target impulsivity. Two forms of non-invasive brain stimulation, namely transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), have been used to modulate impulsivity. To date, no reviews have systematically examined their effects on modulating impulsivity in people with mental health disorders. We conducted a systematic review and meta-analysis of the literature from AMED, Embase, Medline and PsycINFO databases on the use of rTMS and tDCS to modulate impulsivity in people with mental health disorders. Results from 11 tDCS and 18 rTMS studies indicate that tDCS has a significant, albeit small, effect on modulating impulsivity (g = 0.29; 95% CI, 0.09 to 0.48; p = .004) whereas rTMS has no significant effect on impulsivity (g = -0.08; 95% Cl, -0.35 to 0.19; p = .550). Subgroup analyses identified the key parameters required to enhance the effects of tDCS and rTMS on impulsivity. Gender and stimulation intensity acted as significant moderators for effects of rTMS on impulsivity. There is insufficient evidence to support the use of tDCS or rTMS in clinical practice to reduce impulsivity in people with mental health disorders. The use of standardized non-invasive brain stimulation protocols and outcome measures in patients with the same diagnosis is advised to minimize methodological heterogeneity.

Eye tracking of smoking-related stimuli in tobacco use disorder: A proof-of-concept study combining attention bias modification with alpha-transcranial alternating current stimulation

BACKGROUND

Tobacco use disorder (TUD) is characterized by the presence of an attentional bias (AB) towards smoking-related stimuli. We investigated whether combining an AB modification paradigm (ABM) with transcranial alternating current stimulation (tACS) applied over the dorsolateral prefrontal cortex (DLPFC) reduces the AB towards smoking-related stimuli, as well as craving level and impulsive choices.

METHODS

In a sham-controlled, crossover preliminary study, 19 subjects with TUD received two stimulation arms: 1) active tACS (10 Hz, 2 mA, 30 min) combined with ABM and 2) sham tACS combined with ABM, in a randomized order, separated by one week. AB towards smoking cues during passive observation of smoking and neutral cues was assessed with an eye-tracking device and reactions times at a visual-probe task. Craving level was measured with the Questionnaire of Smoking Urges. Impulsive choices were assessed with the delay discounting task.

RESULTS

Active tACS combined with ABM reduced the amount of time spent looking at smoking-related pictures (p = 0.03), prevented the increase of self-reported desire to smoke (p = 0.026), and reduced the proportion of impulsive choices (p = 0.049), compared to sham tACS combined with ABM. No significant effects were reported on other craving dimensions and on AB based on reaction times.

CONCLUSIONS

These preliminary findings suggest that combining tACS with ABM may help smokers who wish to quit by reducing the desire to smoke, attention to smoking-cues, and impulsive decision-making.

Brain Stimulation in Eating Disorders: State of the Art and Future Perspectives

The management of eating disorders (EDs) is still difficult and few treatments are effective. Recently, several studies have described the important contribution of non-invasive brain stimulation (repetitive transcranial magnetic stimulation, transcranial direct current stimulation, and electroconvulsive therapy) and invasive brain stimulation (deep brain stimulation and vagal nerve stimulation) for ED management. This review summarizes the available evidence supporting the use of brain stimulation in ED. All published studies on brain stimulation in ED as well as ongoing trials registered at clinicaltrials.gov were examined. Articles on neuromodulation research and perspective articles were also included. This analysis indicates that brain stimulation in EDs is still in its infancy. Literature data consist mainly of case reports, cases series, open studies, and only a few randomized controlled trials. Consequently, the evidence supporting the use of brain stimulation in EDs remains weak. Finally, this review discusses future directions in this research domain (e.g., sites of modulation, how to enhance neuromodulation efficacy, personalized protocols).

Transcranial direct current stimulation improves quality of life and physical fitness in diabetic polyneuropathy: a pilot double blind randomized controlled trial

Purpose

Diabetes Mellitus (DM) is a chronic disease which presents a big prevalence in the world and several patients with this condition fail to respond to the available treatments. There is a huge unmet clinical need for the development of new therapeutic approaches for this condition. This study aims to evaluate the effects of anodal tDCS on Quality of Life and physical fitness in patients with diabetic polyneuropathy.

Methods

A pilot, parallel, sham, randomized, double-blind trial was conducted with twenty patients. Five consecutive sessions of C3/Fp2 tDCS montage were performed. To assess the primary outcome Short Form 36 Health Survey (SF-36) was used. Physical fitness level, according to lower and upper body strength, flexibility, Time Up and Go Test (TUG) and Six-Minute Walking Test (6MWT) were measured as secondary outcomes. The measures were performed at 3 different times (baseline, 1st and 2nd weeks).

Results

SF-36 increased throughout the protocol, but no difference between groups were found. However, there was a significant difference between groups at 1st and 2nd weeks, which shows a permanent growth in the active-tDCS group. Physical health and functioning, functional capacity and bodily pain showed significant improvements in active-tDCS group in 1st and 2nd weeks during inter-group analysis. Emotional scores showed significant interaction group-time with interaction effects only for active-group in 1st and 2nd weeks. TUG and 6MWT showed significant improvements only in active-tDCS group.

Conclusions

It is suggested that five sessions of anodal M1 tDCS improves QoL and functionality of patients with diabetic polyneuropathy.

Effects of Transcranial Direct Current Stimulation (tDCS) and Approach Bias Modification (ABM) training on food cravings in people taking antipsychotic medication

BACKGROUND

Antipsychotic drug-induced weight gain puts individuals with schizophrenia at increased cardiometabolic risk. As a potential intervention for this problem, we describe the theoretical background and a protocol for a feasibility randomised controlled trial (RCT) of approach bias modification (ABM) training combined with real versus sham (placebo) transcranial direct current stimulation (tDCS). The primary aim of this trial is to obtain information that will guide decision making and protocol development in relation to a future large-scale RCT of ABM and tDCS in this group of participants. Second, the study will assess the preliminary efficacy of ABM + tDCS in reducing food cravings in people who take antipsychotic medication.

METHODS

Thirty adults with a DSM-V diagnosis of schizophrenia or schizoaffective disorder treated with anti-psychotic medication will be randomly allocated to receive five sessions that will combine ABM and real or sham tDCS, in a parallel group design. In this feasibility study, a broad range of outcome variables will be examined. Measures will include food craving, psychopathology (e.g. symptoms of schizophrenia and depression), neuropsychological processes (such as attentional bias and impulsiveness), and the tolerability and acceptability of tDCS. The feasibility of conducting a large-scale RCT of ABM + tDCS and appropriateness of tDCS as a treatment for antipsychotic drug-induced weight gain will be evaluated by assessment of recruitment and retention rates, acceptability of random allocation, blinding success (allocation concealment), completion of treatment sessions and research assessments (baseline, post-treatment and follow-up).

DISCUSSION

The effect sizes generated and other findings from this trial will inform a future large-scale RCT with respect to decisions on primary outcome measures and other aspects of protocol development. In addition, results from this study will provide a preliminary indication of the efficacy of ABM + tDCS treatment for antipsychotic drug-induced weight gain.

TRIAL REGISTRATION

ISRCTN Registry, ISRCTN13280178. Registered on 16 October 2018.

Can transcranial direct current stimulation (tDCS) improve impulsivity in healthy and psychiatric adult populations? A systematic review

Impulsivity is a multidimensional phenomenon that remains hard to define. It compounds the core pathological construct of many neuropsychiatric illnesses, and despite its close relation to suicide risk, it currently has no specific treatment. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique whose application results in cognitive function improvement, both in healthy and psychiatric populations. Following PRISMA recommendations, a systematic review of the literature concerning tDCS's effects on impulsive behaviour was performed using the PubMed database. The research was based on the combination of the keyword 'tDCS' with 'impulsivity', 'response inhibition', 'risk-taking', 'planning', 'delay discounting' or 'craving'. The initial search yielded 309 articles, 92 of which were included. Seventy-four papers demonstrated improvement in task performance related to impulsivity in both healthy and clinical adult populations. However, results were often inconsistent. The conditions associated with improvement, such as tDCS parameters and other aspects that may influence tDCS's outcomes, are discussed. The overall effects of tDCS on impulsivity are promising. Yet further research is required to develop a more comprehensive understanding of impulsivity, allowing for a more accurate assessment of its behavioural outcomes as well as a definition of tDCS therapeutic protocols for impulsive disorders.

Bad Things Come to Those Who Do Not Wait: Temporal Discounting Is Associated With Compulsive Overeating, Eating Disorder Psychopathology and Food Addiction

The tendency to act on immediate pleasure-driven desires, due to the devaluation of future rewards [a process known as temporal discounting (TD)], has been associated with substance use disorders (SUD) and with conditions characterised by compulsive overeating. The study involved a large inclusive participant sample (i.e., no diagnostic or exclusion criteria were applied). They were recruited/assessed online and we investigated whether TD was related to compulsive overeating and associated problems. Participants [N = 432, (48 males)] completed an online survey, which included a hypothetical monetary TD task, the Eating Disorder Examination-Questionnaire (EDE-Q), the Yale Food Addiction Scale (YFAS) and the Depression Anxiety and Stress Scales (DASS). TD correlated with frequency of compulsive overeating and compensatory behaviours, with eating disorder psychopathology, with scores on the YFAS, and with body mass index (BMI). As our study shows that elevated rates of TD are associated with a range of behaviours/measures, we propose that it is more likely that elevated TD rates are a predisposing factor rather than a consequence of the behaviour, i.e., elevated rates of TD contribute to pathological eating-related behaviours; however, a bi-directional explanation is also possible. Future research should investigate whether interventions aimed at reducing TD have clinical potential for treating problematic eating behaviours.

The Use of Electroconvulsive Therapy in Eating Disorders: A Systematic Literature Review and Case Report

OBJECTIVE

The aim of this study was to determine the potential for safe and effective use of electroconvulsive therapy (ECT) in treating eating disorders (EDs) in patients with and without comorbid psychiatric disorders.

METHODS

A review of the literature pertaining to the use of ECT in patients with EDs was performed through PubMed, PsycINFO, and MEDLINE. Search terms included "Electroconvulsive Therapy," "ECT," and "Electroshock" each combined with "Anorexia Nervosa," "Bulimia Nervosa," "Binge Eating Disorder," "Eating Disorder," "EDNOS," and "OSFED." Additionally, a case in which ECT was used in treating a patient with anorexia nervosa is presented.

RESULTS

Eighty-nine articles were reviewed, and 11 were selected for inclusion. These articles detailed 14 patients with active EDs who received ECT during their course of treatment. Of these patients, 13 were noted to have shown improvement in disordered eating after receiving ECT, and no adverse medical outcomes were reported. Our case detailed an additional patient who benefitted from ECT.

CONCLUSIONS

There are limited data supporting the use of ECT in treating EDs; however, there is evidence to support that ECT is safe in this population and has been effective in cases of patients with AN with and without psychiatric comorbidities as well as binge eating disorder. More research is needed for treatment guidelines.

Combining cognitive bias modification training (CBM) and transcranial direct current stimulation (tDCS) to treat binge eating disorder: study protocol of a randomised controlled feasibility trial

INTRODUCTION

Binge eating disorder (BED) is a common mental disorder, closely associated with obesity. Existing treatments are only moderately effective with high relapse rates, necessitating novel interventions. This paper describes the rationale for, and protocol of, a feasibility randomised controlled trial (RCT), evaluating the combination of transcranial direct current stimulation (tDCS) and a computerised cognitive training, namely approach bias modification training (ABM), in patients with BED who are overweight or obese. The aim of this trial is to obtain information that will guide decision-making and protocol development in relation to a future large-scale RCT of combined tDCS+ABM treatment in this group of patients, and also to assess the preliminary efficacy of this intervention.

METHODS AND ANALYSIS

66 participants with Diagnostic and Statistical Manual-5 diagnosis of BED and a body mass index (BMI) of ≥25 kg/m2 will be randomly allocated to one of three groups: ABM+real tDCS; ABM+sham tDCS or a wait-list control group. Participants in both intervention groups will receive six sessions of ABM+real/sham tDCS over 3 weeks; engaging in the ABM task while simultaneously receiving bilateral tDCS to the dorsolateral prefrontal cortex. ABM is based on an implicit learning paradigm in which participants are trained to enact an avoidance behaviour in response to visual food cues. Assessments will be conducted at baseline, post-treatment (3 weeks) and follow-up (7 weeks post-randomisation). Feasibility outcomes assess recruitment and retention rates, acceptability of random allocation, blinding success (allocation concealment), completion of treatment sessions and research assessments. Other outcomes include eating disorder psychopathology and related neurocognitive outcomes (ie, delay of gratification and inhibitory control), BMI, other psychopathology (ie, mood), approach bias towards food and surrogate endpoints (ie, food cue reactivity, trait food craving and food intake).

ETHICS AND DISSEMINATION

This study has been approved by the North West-Liverpool East Research Ethics Committee. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN35717198.

An amygdala-cingulate network underpins changes in effort-based decision making after a fitness program

When humans make decisions, objective rewards are mainly discounted by delay, risk and effort. Whereas recent research has demonstrated that several brain areas process costs and code subjective value in effort-based decision making, it remains obscure how neural activity patterns change when effort costs are reduced due to the acquisition of healthy habits, such as moving from sedentary to active lifestyles. Here, a sample of sedentary volunteers was behaviorally assessed and fMRI-scanned before and after completing a 3-month fitness plan. The impact of effort cost on decisions, measured as the constant defining a hyperbolic decaying function, was reduced after the plan. A logistic mixed model demonstrated that the explanatory power of effort decreased with time. At a neural level, there was a marginally significant disruption of effort-cost related functional activity in the anterior cingulate after the plan. Functional connectivity between the amygdala and anterior cingulate cortex was strengthened after habit acquisition. In turn, this interaction was stronger in those participants with lower effort discounting. Thus, we show for the first time changes in value-based decision making after moving from a sedentary to an active lifestyle, which points to the relevance of the amygdala-cingulate interplay when the impact of effort on decisions fades away.

Approach bias modification training in bulimia nervosa and binge-eating disorder: A pilot randomized controlled trial

OBJECTIVE

Bulimia nervosa (BN) and binge-eating disorder (BED) are associated with poorly controlled approach behavior toward food resulting in binge eating. Approach bias modification (ABM) may reduce these automatic action tendencies (i.e., approach bias) toward food and may thus decrease binge eating and related symptoms.

METHOD

A total of 56 patients with BN/BED participated in this double-blind, randomized controlled trial (RCT) comparing real and sham ABM. The real ABM condition adopted an implicit learning paradigm in which participants were trained to show avoidance behavior in response to food cues. Participants in the sham condition used a similar task but were not trained to avoid food cues. Both conditions comprised 10 training sessions within 4 weeks.

RESULTS

Participants in both groups experienced significant reductions in binge eating, eating disorder symptoms, trait food craving, and food cue reactivity. Real ABM tended to result in greater reductions in eating disorder symptoms than sham ABM. Food intake, approach bias, and attention bias toward food did not change.

DISCUSSION

This is the first RCT on ABM in eating disorders. The findings provide limited support for the efficacy of ABM in BN/BED and pose questions regarding its active ingredients and its usefulness as a stand-alone treatment for eating disorders.

Transcranial direct current stimulation modulates implicit attitudes towards food in eating disorders

OBJECTIVE

Neuromodulation of regions involved in food processing is increasingly used in studies on eating behaviors, but results are controversial. We assessed the effects of anodal transcranial direct current stimulation (a-tDCS) on food and body implicit preferences in patients with eating disorders (EDs).

METHOD

Thirty-six ED patients and 36 healthy females completed three sessions with a-tDCS applied to the medial-prefrontal cortex (mPFC), the right extrastriate body area (rEBA) or in sham mode. Each participant then completed three Implicit Association Tests (IATs) on tasty/tasteless food, underweight/overweight body images, flowers versus insects as control. Differences in latency between incongruent and congruent blocks were calculated (D score).

RESULTS

The tDCS by group interaction was significant for the IAT-food D score, with patients showing weaker preference for tasty food than controls in sham, but not a-tDCS sessions. In particular, rEBA stimulation significantly increased patients' D score compared to sham. Moreover, a-tDCS over mPFC and rEBA selectively increased patients' reaction times in the incongruent blocks of the IAT-food.

DISCUSSION

A-tDCS on frontal and occipito-temporal cortices modulated food preferences in ED patients. The effect was specific for food images and selective in patients, but not in healthy participants. These findings suggest that neuromodulation of these regions could affect implicit food attitudes.

Cognitive Neuroscience of Eating Disorders

Anorexia nervosa and bulimia nervosa are characterized by severely restricted intake, binge eating, and compensatory behaviors like self-induced vomiting. The neurobiological underpinnings of these maladaptive behaviors are poorly understood, but the application of cognitive neuroscience and neuroimaging to eating disorders has begun to elucidate their pathophysiology. Specifically, this review focuses on 3 areas that suggest paths forward: reward, cognitive and behavioral control, and decision making. Understanding the brain-based mechanisms that promote and maintain these often chronic symptoms could guide the development of new and more effective treatments.

Polarity Specific Effects of Cross-Hemispheric tDCS Coupled With Approach-Avoidance Training on Chocolate Craving

Transcranial Direct Current Stimulation (tDCS) over the Dorsolateral Prefrontal Cortex (DLPFC) has already been shown to decrease craving for food. However, it remains unclear whether a single session of tDCS combined with a cognitive bias modification (CBM) task may affect explicit and implicit measures of craving for chocolate. Fifty-one healthy volunteers (38 females; mean age: 22.12 ± 3.38) were randomly allocated to CBM training based on the Approach Avoidance task and either Sham, Right anodal-Left cathodal (RALC), or Left anodal-Right cathodal (LARC) tDCS. Results show that there was an increase in the explicit craving for chocolate, as assessed by the Visual Analog Scale [F(2, 46) = 3.239, p = 0.048], from the baseline to post-intervention. Participants which received LARC tDCS were explicitly self-reporting more craving for chocolate than those that received RALC tDCS (p = 0.023). Moreover, this effect was also observed on the implicit measure [F(2, 46) = 4.168, p = 0.022]. LARC tDCS significantly increased the implicit preference for chocolate when comparing to both RALC (p = 0.009) and Sham tDCS (p = 0.034). Previous studies have shown that RALC tDCS over the PFC is able to effectively decrease craving for food. Interestingly, the present data not only does not reproduce such result, but instead it suggests that LARC tDCS can actually increase the preference for chocolate. This result is compatible with recent models of brain laterality, in which cue craving seems to be more dependent on the left hemisphere. Thus, shifting the activity to the left hemisphere (while simultaneously reducing the activity over the homotopic region) may have led to this increased implicit as well as explicit preference for chocolate.

Enhancement of Mood but not Performance in Elite Athletes With Transcranial Direct-Current Stimulation

PURPOSE

To determine if transcranial direct-current stimulation (tDCS) could be effective for the enhancement of swimming performance or mood state in elite athletes.

METHODS

Eight male elite triathletes (age = 20 [2] y, maximal oxygen uptake = 71 [4] mL·kg^-1·min^-1) participated in this crossover, counterbalanced, sham-controlled, double-blind study. Participants received either actual (20 min of anodal stimulation of the motor cortex at 2 mA) or sham tDCS and performed an 800-m swimming test in which rating of perceived exertion and blood lactate response were measured. Mood state (Brunel Mood Scale) was assessed before and after each tDCS session and after the swimming test. Heart-rate variability and central nervous system readiness were assessed before and after each tDCS session. The chances of finding differences between conditions were determined using magnitude-based inferences.

RESULTS

A significant and very likely higher Brunel Mood Scale-determined vigor self-perception was found with actual tDCS after the stimulation session (-0.1 [1.2] and 2.0 [2.3] for sham and actual tDCS, respectively; P = .018, effect size = 1.14) and after exercise (-4.1 [2.9] and -0.9 [3.6] for sham and actual tDCS, respectively; P = .022, effect size = 0.98). However, likely trivial and nonsignificant (P > .05) differences were found between conditions in performance (599 [38] s and 596 [39] s, respectively). Unclear and nonsignificant differences were observed between conditions for the rest of the study end points.

CONCLUSIONS

tDCS elicited a marked increase in vigor self-perception that was maintained after exercise but failed to improve swimming performance in elite triathletes.

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.

Food cue-induced craving in individuals with bulimia nervosa and binge-eating disorder

Individuals with bulimia nervosa (BN) or binge-eating disorder (BED) experience more frequent and intense food cravings than individuals without binge eating. However, it is currently unclear whether they also show larger food cue-induced increases in craving (i.e., food cue reactivity) than those without binge eating, as suggested by conditioning theories of binge eating. A group of individuals with BN or BED (binge-eating group, n = 27) and a group of individuals with low trait food craving scores and without binge eating (control group, n = 19) reported their current food craving before and after a food cue exposure. Although food craving intensity significantly increased in both groups, this increase was significantly stronger in the binge-eating group than in the control group. This result is in line with conditioning models of binge eating that propose that food cues are conditioned stimuli that elicit a conditioned response (e.g., food craving) and that this association is stronger in individuals with binge eating. As food craving increased in individuals with low trait food craving scores as well-although to a lesser extent-previous null results might be explained by methodological considerations such as not screening control participants for trait food craving.

Is transcranial direct current stimulation an effective modality in reducing food craving? A systematic review and meta-analysis

Non-invasive electrical stimulation of the brain has recently been extensively investigated to regulate food craving. However, the existing literature is controversial and there are some important questions which need to be addressed about clinical and technical factors contributing to efficacy of this method. A systematic search was performed in reliable scientific databases, and 15 eligible studies were identified. The pooled standardized mean differences for the effects of transcranial direct current stimulation (tDCS) on Visual Analogue Scale, energy intake and food craving questionnaire were -0.78 [-1.12, -0.44], -0.91 [-1.38, -0.44], -0.54 [-0.85, -0.24], respectively. Subgroup analysis showed that the most important factors associated with the impact of tDCS on food craving were the population under study, current intensity of stimulation, and number of stimulation sessions. The findings of this study support a significant impact of neuromodulation of dorsolateral prefrontal cortex (DLPFC) on energy intake and food craving using tDCS. It is recommended that multisession bilateral stimulation of the DLPFC with the current intensity of 2 mA be used to reduce food craving.

Transcranial DC stimulation modifies functional connectivity of large-scale brain networks in abstinent methamphetamine users

Background

Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation tool suited to alter cortical excitability and activity via the application of weak direct electrical currents. An increasing number of studies in the addiction literature suggests that tDCS modulates subjective self-reported craving through stimulation of dorsolateral prefrontal cortex (DLPFC). The major goal of this study was to explore effects of bilateral DLPFC stimulation on resting state networks (RSNs) in association with drug craving modulation. We targeted three large-scale RSNs; the default mode network (DMN), the executive control network (ECN), and the salience network (SN).

Methods

Fifteen males were recruited after signing written informed consent. We conducted a double-blinded sham-controlled crossover study. Twenty-minute "real" and "sham" tDCS (2 mA) were applied over the DLPFC on two separate days in random order. Each subject received both stimulation conditions with a 1-week washout period. The anode and cathode electrodes were located over the right and left DLPFC, respectively. Resting state fMRI was acquired before and after real and sham stimulation. Subjective craving was assessed before and after each fMRI scan. The RSNs were identified using seed-based analysis and were compared using a generalized linear model.

Results

Subjective craving decreased significantly after real tDCS compared to sham stimulation (p = .03). Moreover, the analysis shows significant modulation of DMN, ECN, and SN after real tDCS compared to sham stimulation. Additionally, alteration of subjective craving score was correlated with modified activation of the three networks.

Discussion

Given the observed alteration of the targeted functional brain networks in methamphetamine users, new potentials are highlighted for tDCS as a network intervention strategy and rsfMRI as a suitable monitoring method for these interventions.

Neuromodulation for the treatment of eating disorders and obesity

Eating disorders and obesity adversely affect individuals both medically and psychologically, leading to reduced life expectancy and poor quality of life. While there exist a number of treatments for anorexia, morbid obesity and bulimia, many patients do not respond favorably to current behavioral, medical or bariatric surgical management. Neuromodulation has been postulated as a potential treatment for eating disorders and obesity. In particular, deep brain stimulation and transcranial non-invasive brain stimulation have been studied for these indications across a variety of brain targets. Here, we review the neurobiology behind eating and eating disorders as well as the current status of preclinical and clinical neuromodulation trials for eating disorders and obesity.

Neurostimulation in Clinical and Sub-clinical Eating Disorders: A Systematic Update of the Literature

INTRODUCTION

Whilst psychological therapies are the main approach to treatment of eating disorders (EDs), advances in aetiological research suggest the need for the development of more targeted, brain-focused treatments. A range of neurostimulation approaches, most prominently repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS), are rapidly emerging as potential novel interventions. We have previously reviewed these techniques as potential treatments of EDs.

AIM

To provide an update of the literature examining the effects of DBS, rTMS and tDCS on eating behaviours, body weight and associated symptoms in people with EDs and relevant analogue populations.

METHODS

Using PRISMA guidelines, we reviewed articles in PubMed, Web of Science, and PsycINFO from 1st January 2013 until 14th August 2017, to update our earlier search. Studies assessing the effects of neurostimulation techniques on eating and weight-related outcomes in people with EDs and relevant analogue populations were included. Data from both searches were combined.

RESULTS

We included a total of 32 studies (526 participants); of these, 18 were newly identified by our update search. Whilst findings are somewhat mixed for bulimia nervosa, neurostimulation techniques have shown potential in the treatment of other EDs, in terms of reduction of ED and associated symptoms. Studies exploring cognitive, neural, and hormonal correlates of these techniques are also beginning to appear.

CONCLUSIONS

Neurostimulation approaches show promise as treatments for EDs. As yet, large wellconducted randomised controlled trials are lacking. More information is needed about treatment targets, stimulation parameters and mechanisms of action.

Neuromodulation in eating disorders and obesity: a promising way of treatment?

Neuromodulation can affect the functioning of the central nervous system (CNS), and emotional/eating behavior is an exciting facet of that functioning. Therefore, it would be possible to offer an alternative (or complement) treatment to psychotropic medications and different psychological and nutritional approaches to both eating disorders (EDs) and obesity. Although there are a number of publications in these areas, a systematic review has not been conducted to date. Abstracts, letters, conference reports, dissertations, and reviews were excluded. Clinical trials and controlled human clinical trials were filtered and included in this study. Articles included were based on the population suffering from anorexia nervosa, bulimia nervosa, binge ED, overweight, and obesity. No restrictions were placed on the sample size. Only trials investigating the effect of neuromodulation by means of deep brain stimulation (DBS), transcranial direct current stimulation (tDCS), and transcranial magnetic stimulation (TMS) were included. The following databases were used to conduct the search: MEDLINE/ PubMed, PsycINFO, PsycArticles, and Cochrane (Search Trials, CENTRAL). Study selection was performed following the PRISMA process (PRISMA 2009 Checklist). The total number of participants in all the trials was 562 (DBS, 25; tDCS, 138; TMS, 399; range, 3-90; median, 23.5). As a result, 50% of the studies had samples of between 14 and 38 participants. Neuro-modulation in ED seems to have certain clinical potential, and therefore, this is a promising area for further research. Developments in ED neuromodulation will be linked to neuroimaging to identify potential stimulation targets and possible biomarkers of treatment response. To date, TMS and/or direct current stimulation (DCS) is not the first-line treatment yet, but it could become a preferred option of treatment in the future. Further studies should avoid small sample sizes and the use of different methodologies. Currently, neuromodulation techniques are in the experimental phase, and they are not an evidence-based treatment for ED.

The Role of Transcranial Direct Current Stimulation (tDCS) in Tourette Syndrome: A Review and Preliminary Findings

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is being investigated for a variety of neurological and psychiatric conditions. Preliminary evidence suggests that tDCS may be useful in the treatment of Tourette Syndrome (TS). This paper reviews the literature on the use of tDCS in commonly occurring comorbid conditions that are relevant to its proposed use in TS. We describe the protocol for a double-blind, crossover, sham-controlled trial of tDCS (Trial ID: ACTRN12615000592549, registered at www.anzctr.org.au) investigating the efficacy, feasibility, safety, and tolerability of tDCS in patients with TS aged 12 years and over. The intervention consists of cathodal tDCS positioned over the Supplementary Motor Area. Patients receive either sham tDCS for three weeks followed by six weeks of active tDCS (1.4 mA, 18 sessions over six weeks), or six weeks of active sessions followed by three weeks of sham sessions, with follow-up at three and six months. Pilot findings from two patients are presented. There was a reduction in the frequency and intensity of patients’ tics and premonitory urges, as well as evidence of improvements in inhibitory function, over the course of treatment. Larger scale studies are indicated to ascertain the maintenance of symptom improvement over time, as well as the long-term consequences of the repetitions of sessions.