The Potential of Neurofeedback in the Treatment of Eating Disorders: A Review of the Literature

[Effects of non-invasive neuromodulation on the cognitive profile of people with anorexia nervosa: A scoping review]

BACKGROUND

The use of non-invasive neuromodulation is emerging in the treatment of anorexia nervosa. Despite promising results, further research is needed to improve our understanding of these techniques and to adapt interventions to this population. As anorexia nervosa is associated with several cognitive difficulties and cerebral anomalies, the aim of the present study was to summarize the available data on the effects of non-invasive neuromodulation on the neuropsychological profile of people with anorexia nervosa.

METHOD

A scoping review was conducted by searching in PsycINFO, PubMed and CINAHL databases to systematically identify relevant studies published between 1994 and 2023 on the treatment of anorexia nervosa with repetitive transcranial magnetic stimulation, transcranial direct current stimulation or neurofeedback electroencephalogram.

RESULTS

Seventeen articles were included, including 12 on repetitive transcranial magnetic stimulation, four on transcranial direct current stimulation and one on neurofeedback electroencephalogram. Of these, only three studies included a neuropsychological measure to assess the impact of neuromodulation on participants' cognitive functions.

CONCLUSIONS

Including detailed neuropsychological measures in clinical trials of non-invasive neuromodulation is highly recommended and appears essential to improve our understanding of these techniques and optimize their efficacy in the treatment of anorexia nervosa.

Predictors of neurofeedback treatment outcome in binge-eating disorder: An exploratory study

OBJECTIVE

Knowledge on predictors for treatment response to psychotherapy in binge-eating disorder (BED) is mixed and not yet available for increasingly popular neurofeedback (NF) treatment targeting self-regulation of aberrant brain activity. This study examined eating disorder- and psychopathology-related predictors for NF treatment success in BED.

METHOD

Patients with BED (N = 78) were randomized to 12 sessions of real-time functional near-infrared spectroscopy (rtfNIRS)-NF, targeting individual prefrontal cortex signal up-regulation, electroencephalography (EEG)-NF, targeting down-regulation of fronto-central beta activity, or waitlist (WL). The few studies assessing predictors for clinical outcomes after NF and evidenced predictors for psychotherapy guided the selection of baseline eating disorder-related predictors, including objective binge-eating (OBE) frequency, eating disorder psychopathology (EDP), food cravings, and body mass index (BMI), and general psychopathology-related predictors, including depressive and anxiety symptoms, impulsivity, emotion dysregulation, and self-efficacy. These questionnaire-based or objectively assessed (BMI) predictors were regressed on outcomes OBE frequency and EDP as key features of BED at post-treatment (t1) and 6-month follow-up (t2) in preregistered generalized mixed models (https://osf.io/4aktp).

RESULTS

Higher EDP, food cravings, and BMI predicted worse outcomes across all groups at t1 and t2. General psychopathology-related predictors did not predict outcomes at t1 and t2. Explorative analyses indicated that lower OBE frequency and higher self-efficacy predicted lower OBE frequency, and lower EDP predicted lower EDP after the waiting period in WL.

DISCUSSION

Consistent with findings for psychotherapy, higher eating disorder-related predictors were associated with higher EDP and OBE frequency. The specificity of psychopathological predictors for NF treatment success warrants further examination.

PUBLIC SIGNIFICANCE

This exploratory study firstly assessed eating disorder- and psychopathology-related predictors for neurofeedback treatment outcome in binge-eating disorder and overweight. Findings showed an association between higher eating disorder symptoms and worse neurofeedback outcomes, indicating special needs to be considered in neurofeedback treatment for patients with a higher binge-eating disorder symptom burden. In general, outcomes and assignment to neurofeedback treatment may be improved upon consideration of baseline psychological variables.

Computationally Informed Interventions for Targeting Compulsive Behaviors

Compulsive behaviors are central to addiction and obsessive-compulsive disorder and can be understood as a failure of adaptive decision making. Particularly, they can be conceptualized as an imbalance in behavioral control, such that behavior is guided predominantly by learned rather than inferred outcome expectations. Inference is a computational process required for adaptive behavior, and recent work across species has identified the neural circuitry that supports inference-based decision making. This includes the orbitofrontal cortex, which has long been implicated in disorders of compulsive behavior. Inspired by evidence that modulating orbitofrontal cortex activity can alter inference-based behaviors, here we discuss noninvasive approaches to target these circuits in humans. Specifically, we discuss the potential of network-targeted transcranial magnetic stimulation and real-time neurofeedback to modulate the neural underpinnings of inference. Both interventions leverage recent advances in our understanding of the neurocomputational mechanisms of inference-based behavior and may be used to complement current treatment approaches for behavioral disorders.

Complementary and Integrative Medicine and Eating Disorders in Youth: Traditional Yoga, Virtual Reality, Light Therapy, Neurofeedback, Acupuncture, Energy Psychology Techniques, Art Therapies, and Spirituality

Eating disorders (EDs) are a non-heterogeneous group of illnesses with significant physical and mental comorbidity and mortality associated with maladaptive coping. With the exception of lisdexamfetamine (Vyvanse) for binge eating disorder, no medications have been effective for the core symptoms of ED. ED requires a multimodal approach. Complementary and integrative medicine (CIM) can be helpful as an adjunct. The most promising CIM interventions are traditional yoga, virtual reality, eye movement desensitization and reprocessing, Music Therapy, and biofeedback/neurofeedback.

Probing fMRI brain connectivity and activity changes during emotion regulation by EEG neurofeedback

Despite the existence of several emotion regulation studies using neurofeedback, interactions among a small number of regions were evaluated, and therefore, further investigation is needed to understand the interactions of the brain regions involved in emotion regulation. We implemented electroencephalography (EEG) neurofeedback with simultaneous functional magnetic resonance imaging (fMRI) using a modified happiness-inducing task through autobiographical memories to upregulate positive emotion. Then, an explorative analysis of whole brain regions was done to understand the effect of neurofeedback on brain activity and the interaction of whole brain regions involved in emotion regulation. The participants in the control and experimental groups were asked to do emotion regulation while viewing positive images of autobiographical memories and getting sham or real (based on alpha asymmetry) EEG neurofeedback, respectively. The proposed multimodal approach quantified the effects of EEG neurofeedback in changing EEG alpha power, fMRI blood oxygenation level-dependent (BOLD) activity of prefrontal, occipital, parietal, and limbic regions (up to 1.9% increase), and functional connectivity in/between prefrontal, parietal, limbic system, and insula in the experimental group. New connectivity links were identified by comparing the brain functional connectivity between experimental conditions (Upregulation and View blocks) and also by comparing the brain connectivity of the experimental and control groups. Psychometric assessments confirmed significant changes in positive and negative mood states in the experimental group by neurofeedback. Based on the exploratory analysis of activity and connectivity among all brain regions involved in emotion regions, we found significant BOLD and functional connectivity increases due to EEG neurofeedback in the experimental group, but no learning effect was observed in the control group. The results reveal several new connections among brain regions as a result of EEG neurofeedback which can be justified according to emotion regulation models and the role of those regions in emotion regulation and recalling positive autobiographical memories.

From Virtual Reality to Regenerative Virtual Therapy: Some Insights from a Systematic Review Exploring Inner Body Perception in Anorexia and Bulimia Nervosa

Despite advances in our understanding of the behavioral and molecular factors that underlie the onset and maintenance of Eating Disorders (EDs), it is still necessary to optimize treatment strategies and establish their efficacy. In this context, over the past 25 years, Virtual Reality (VR) has provided creative treatments for a variety of ED symptoms, including body dissatisfaction, craving, and negative emotions. Recently, different researchers suggested that EDs may reflect a broader impairment in multisensory body integration, and a particular VR technique-VR body swapping-has been used to repair it, but with limited clinical results. In this paper, we use the results of a systematic review employing PRISMA guidelines that explore inner body perception in EDs (21 studies included), with the ultimate goal to analyze the features of multisensory impairment associated with this clinical condition and provide possible solutions. Deficits in interoception, proprioception, and vestibular signals were observed across Anorexia and Bulimia Nervosa, suggesting that: (a) alteration of inner body perception might be a crucial feature of EDs, even if further research is needed and; (b) VR, to be effective with these patients, has to simulate/modify both the external and the internal body. Following this outcome, we introduce a new therapeutic approach-Regenerative Virtual Therapy-that integrates VR with different technologies and clinical strategies to regenerate a faulty bodily experience by stimulating the multisensory brain mechanisms and promoting self-regenerative processes within the brain itself.

Interactions between emotions and eating behaviors: Main issues, neuroimaging contributions, and innovative preventive or corrective strategies

Emotional eating is commonly defined as the tendency to (over)eat in response to emotion. Insofar as it involves the (over)consumption of high-calorie palatable foods, emotional eating is a maladaptive behavior that can lead to eating disorders, and ultimately to metabolic disorders and obesity. Emotional eating is associated with eating disorder subtypes and with abnormalities in emotion processing at a behavioral level. However, not enough is known about the neural pathways involved in both emotion processing and food intake. In this review, we provide an overview of recent neuroimaging studies, highlighting the brain correlates between emotions and eating behavior that may be involved in emotional eating. Interaction between neural and neuro-endocrine pathways (HPA axis) may be involved. In addition to behavioral interventions, there is a need for a holistic approach encompassing both neural and physiological levels to prevent emotional eating. Based on recent imaging, this review indicates that more attention should be paid to prefrontal areas, the insular and orbitofrontal cortices, and reward pathways, in addition to regions that play a major role in both the cognitive control of emotions and eating behavior. Identifying these brain regions could allow for neuromodulation interventions, including neurofeedback training, which deserves further investigation.

The importance of self-efficacy and negative affect for neurofeedback success for central neuropathic pain after a spinal cord injury

EEG-based neurofeedback uses mental behaviours (MB) to enable voluntary self-modulation of brain activity, and has potential to relieve central neuropathic pain (CNP) after a spinal cord injury (SCI). This study aimed to understand neurofeedback learning and the relationship between MB and neurofeedback success. Twenty-five non-CNP participants and ten CNP participants received neurofeedback training (reinforcing 9–12 Hz; suppressing 4–8 Hz and 20–30 Hz) on four visits. Participants were interviewed about the MB they used after each visit. Questionnaires examined the following factors: self-efficacy, locus of control, motivation, and workload of neurofeedback. MB were grouped into mental strategies (a goal-directed mental action) and affect (emotional experience during neurofeedback). Successful non-CNP participants significantly used more imagination-related MS and reported more negative affect compared to successful CNP participants. However, no mental strategy was clearly associated with neurofeedback success. There was some association between the lack of success and negative affect. Self-efficacy was moderately correlated with neurofeedback success (r = < 0.587, p = < 0.020), whereas locus of control, motivation, and workload had low, non-significant correlations (r < 0.300, p > 0.05). Affect may be more important than mental strategies for a successful neurofeedback performance. Self-efficacy was associated with neurofeedback success, suggesting that increasing confidence in one’s neurofeedback abilities may improve neurofeedback performance.

Resting state differences between successful and unsuccessful restrained eaters

Restrained eating is a popular weight loss strategy for young women that tends to have limited effectiveness over extended periods of time. Although previous studies have explored and identified possible personality and behavior differences between successful and unsuccessful restrained eaters (REs), there has been a paucity of research on neurophysiological differences.Towards addressing this gap, we assessed brain resting state (Rs) differences in groups of unsuccessful REs (N = 39) and successful REs (N = 31). In line with hypotheses, unsuccessful REs displayed reduced regional homogeneity in brain regions involved in cognitive control (inferior parietal lobe) compared to successful REs. Regions involved in conflict monitoring (anterior cingulate cortex) were also observed to be comparatively less active in the unsuccessful RE group. Finally, based on analyses of independent components and seed-based functional connectivity, regions involved in conflict monitoring and cognitive control, especially those localized within the frontoparietal network, showed weaker connectivities among unsuccessful REs compared to their successful counterparts.These results underscore specific brain Rs differences between successful REs and unsuccessful REs in regions implicated in cognitive control and conflict monitoring.

Believing is achieving - On the role of treatment expectation in neurofeedback applications

In neurofeedback applications, neural activity is recorded, processed in real-time and fed back to the user in order to facilitate self-regulation of the putative neural mechanisms that underlie cognition and behavior. Numerous studies suggest that neurofeedback interventions are an efficacious treatment particularly for patients with attention-deficit/hyperactivity disorder (ADHD). In recent years, however, findings of several well-controlled studies raised doubts concerning the proposed mechanism of action behind the behavioral effect of neurofeedback. This study investigated the impact of expectation on the efficacy of a sensorimotor rhythm (SMR) training. In a within-subjects design 30 blinded volunteers with ADHD symptoms received a standard SMR training session after inducing no (no-expectancy condition), positive (placebo condition), and negative (nocebo condition) expectations regarding the effectiveness of neurofeedback (by telling them that they would train a specific frequency band that was previously shown to be either unrelated to attention, should improve attention, or interfere with attentional processes). After each training, participants were presented with a cognitive test and subsequently requested to rate their performance on it. We could show that participants were able to successfully modify their EEG signal during training. Further, we found an effect over trainings on objective attentional performance. Most importantly, we found that the expectancy of positive or negative treatment effects considerably changed participants' perception of neurofeedback's efficacy even in the absence of any objective evidence. This study presents strong first evidence for a substantial effect of self-confirming response expectancies as one factor underlying the efficacy of neurofeedback. Future research has to carefully consider the impact of such psychosocial mechanisms when evaluating the (specific) efficacy of neuromodulatory treatments.

The Influence of Physiological and Psychological Learning Mechanisms in Neurofeedback vs. Mental Imagery Against Binge Eating

In biofeedback research, the debate on physiological versus psychological learning has a long tradition and is still relevant today, regarding new developments of biofeedback for behavior modification. Analyzing the role of these learning mechanisms may help improving the protocols and answer the question, whether feedback of physiological functions is necessary to modify a target behavior. We explored the presence and impact of physiological (EEG changes) versus psychological learning (changes in somatic self-efficacy) in a recently developed EEG neurofeedback protocol for binge eating. The protocol targets a reduction of food-cue induced cortical arousal through regulation of EEG high beta activity. In an experimental study accompanying a randomized controlled trial, pre and post treatment EEG measurements were analyzed in a neurofeedback group (n = 18) and an active mental imagery control group without physiological feedback (n = 18). Physiological learning in terms of EEG high beta reduction only occurred in the neurofeedback group. Post treatment, participants with successfully reduced binge eating episodes (≥ 50% reduction) showed lower EEG high beta activity than unsuccessful participants (p = .02) after neurofeedback, but not after mental imagery. Further, lower EEG high beta activity at post-treatment predicted fewer binge eating episodes in neurofeedback only. In mental imagery, somatic self-efficacy predicted treatment success instead of EEG activity. Altogether, the results indicate that physiological changes serve as a specific treatment mechanism in neurofeedback against binge eating. Reducing cortical arousal may improve eating behaviors and corresponding neurofeedback techniques should therefore be considered in future treatments.

What Should I Eat and Why? The Environmental, Genetic, and Behavioral Determinants of Food Choice: Summary from a Pennington Scientific Symposium

This review details the proceedings of a Pennington Biomedical scientific symposium titled, "What Should I Eat and Why? The Environmental, Genetic, and Behavioral Determinants of Food Choice." The symposium was designed to review the literature about energy homeostasis, particularly related to food choice and feeding behaviors, from psychology to physiology. This review discusses the intrinsic determinants of food choice, including biological mechanisms (genetics), peripheral and central signals, brain correlates, and the potential role of the microbiome. This review also address the extrinsic determinants (environment) of food choice within our physical and social environments. Finally, this review reports the current treatment practices for the clinical management of eating-induced overweight and obesity. An improved understanding of these determinants will inform best practices for the clinical treatment and prevention of obesity. Strategies paired with systemic shifts in our public health policies and changes in our "obesogenic" environment will be most effective at attenuating the obesity epidemic.

Feedback-Based Treatments for Eating Disorders and Related Symptoms: A Systematic Review of the Literature

The effectiveness of biofeedback and neurofeedback has been investigated in a range of psychiatric disorders. However, to date, there are few studies on the clinical usefulness of feedback-based techniques for eating disorders (EDs) and EDs-related symptoms (e.g., food craving). A systematic search of PubMed, Scopus and PsychINFO identified 162 articles. Among these, thirteen studies exploring the therapeutic use of biofeedback and neurofeedback in EDs or EDs-related symptoms were included. Biofeedback and neurofeedback were implemented respectively in five and eight of all reviewed articles. No studies incorporated different feedback modalities or both biofeedback and neurofeedback. The considered studies provide preliminary data of the usefulness of feedback-based techniques in the treatment of several dysfunctional eating behaviors (e.g., food craving, rumination). Although no significant effect has been reported for other important EDs-related symptoms (i.e., body image disturbance), feedback-based techniques are also associated with significant modifications of both sympathetic reaction to food-related stimuli and brain activity in several regions of the reward system (e.g., insula). Taken together the results of the present review suggest that feedback-based treatments may be useful in the treatment of several dysfunctional eating behaviors operating both on top-down and bottom-up individual coping strategies. Methodological and clinical issues are also discussed.

Current state of the use of neuroimaging techniques to understand and alter appetite control in humans

PURPOSE OF REVIEW

It is in the brain where the decision is made what and how much to eat. In the last decades neuroimaging research has contributed extensively to new knowledge about appetite control by revealing the underlying brain processes. Interestingly, there is the fast growing idea of using these methods to develop new treatments for obesity and eating disorders. In this review, we summarize the findings of the importance of the use of neuropharmacology and neuroimaging techniques in understanding and modifying appetite control.

RECENT FINDINGS

Appetite control is a complex interplay between homeostatic, hedonic, and cognitive processes. Administration of the neuropeptides insulin and oxytocin curb food intake and alter brain responses in reward and cognitive control areas. Additionally, these areas can be targeted for neuromodulation or neurofeedback to reduce food cravings and increase self-control to alter food intake.

SUMMARY

The recent findings reveal the potential of intranasal administration of hormones or modifying appetite control brain networks to reduce food consumption in volunteers with overweight and obesity or individuals with an eating disorder. Although long-term clinical studies are still needed.

Advances in the treatment of anorexia nervosa: a review of established and emerging interventions

BACKGROUND

Anorexia nervosa (AN) is a disabling, deadly and costly mental disorder. Until recently, treatment recommendations were based on expert opinion and limited evidence. The aim of this systematic review is to synthesise recent evidence on established and emerging AN treatments and to forecast trends for future developments.

METHODS

We systematically review trials of established treatments and associated process outcome studies from the last 5 years, published since a previous review in this journal. 'Established' treatments were those that are widely used in AN, recommended by guidelines and/or have been tested in at least one large randomised controlled trial. Secondly, we summarise emerging treatments for AN, i.e. those that have only been (or are currently being) tested in proof-of concept, feasibility or pilot trials.

RESULTS

We identified 19 published trials of established treatments (15 of high or moderate quality), mostly assessing psychological therapies (n = 17). We also found 11 published trials of emerging treatments, and a total of 34 registered, as yet unpublished trials. Promising emerging treatments include cognitive remediation therapy, exposure therapy and non-invasive neuromodulation.

CONCLUSIONS

Evidence generation on the treatment of AN has dramatically accelerated, with our understanding of the role of family-based approaches for adolescents more nuanced and a range of psychological approaches available for the treatment of adults. Evidence on emerging treatments and from forthcoming trials suggests that there is a shift towards more targeted brain-based interventions. Future studies need to focus on elucidating mechanisms of action of treatments and what works best for whom.

Self-guided Change: The most common form of long-term, maintained health behavior change

Millions of people change risky, health-related behaviors and maintain those changes. However, they often take years to change, and their unhealthy behaviors may harm themselves and others and constitute a significant cost to society. A review-similar in nature to a scoping review-was done of the literature related to long-term health behavior change in six areas: alcohol, cocaine and heroin misuse, gambling, smoking, and overeating. Based on the limited research available, reasons for change and strategies for changing and for maintaining change were also reviewed. Fifty years of research clearly indicate that as people age, in the case of alcohol, heroin and cocaine misuse, smoking, and gambling, 80-90 percent moderate or stop their unhealthy behaviors. The one exception is overeating; only 20 percent maintain their weight loss. Most of these changes, when they occur, appear to be the result of self-guided change. More ways to accelerate self-guided, health-related behavior change need to be developed and disseminated.

Neuroimaging in bulimia nervosa and binge eating disorder: a systematic review

OBJECTIVE

In recent decades there has been growing interest in the use of neuroimaging techniques to explore the structural and functional brain changes that take place in those with eating disorders. However, to date, the majority of research has focused on patients with anorexia nervosa. This systematic review addresses a gap in the literature by providing an examination of the published literature on the neurobiology of individuals who binge eat; specifically, individuals with bulimia nervosa (BN) and binge eating disorder (BED).

METHODS

A systematic review was conducted in accordance with PRISMA guidelines using PubMed, PsycInfo, Medline and Web of Science, and additional hand searches through reference lists. 1,003 papers were identified in the database search. Published studies were included if they were an original research paper written in English; studied humans only; used samples of participants with a diagnosed eating disorder characterised by recurrent binge eating; included a healthy control sample; and reported group comparisons between clinical groups and healthy control groups.

RESULTS

Thirty-two papers were included in the systematic review. Significant heterogeneity in the methods used in the included papers coupled with small sample sizes impeded the interpretation of results. Twenty-one papers utilised functional Magnetic Resonance Imaging (fMRI); seven papers utilized Magnetic Resonance Imaging (MRI) with one of these using both MRI and Positron Emission Technology (PET); three studies used Single-Photon Emission Computed Tomography (SPECT) and one study used PET only. A small number of consistent findings emerged in individuals in the acute phase of illness with BN or BED including: volume reduction and increases across a range of areas; hypoactivity in the frontostriatal circuits; and aberrant responses in the insula, amygdala, middle frontal gyrus and occipital cortex to a range of different stimuli or tasks; a link between illness severity in BN and neural changes; diminished attentional capacity and early learning; and in SPECT studies, increased rCBF in relation to disorder-related stimuli.

CONCLUSIONS

Studies included in this review are heterogenous, preventing many robust conclusions from being drawn. The precise neurobiology of BN and BED remains unclear and ongoing, large-scale investigations are required. One clear finding is that illness severity, exclusively defined as the frequency of binge eating or bulimic episodes, is related to greater neural changes. The results of this review indicate additional research is required, particularly extending findings of reduced cortical volumes and diminished activity in regions associated with self-regulation (frontostriatal circuits) and further exploring responses to disorder-related stimuli in people with BN and BED.

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.

Interactions between metabolic, reward and cognitive processes in appetite control: Implications for novel weight management therapies

Traditional models of appetite control have emphasised the role of parallel homeostatic and hedonic systems, but more recently the distinction between independent homeostatic and hedonic systems has been abandoned in favour of a framework that emphasises the cross talk between the neurochemical substrates of the two systems. In addition, evidence has emerged more recently, that higher level cognitive functions such as learning, memory and attention play an important role in everyday appetite control and that homeostatic signals also play a role in cognition. Here, we review this evidence and present a comprehensive model of the control of appetite that integrates cognitive, homeostatic and reward mechanisms. We discuss the implications of this model for understanding the factors that may contribute to disordered patterns of eating and suggest opportunities for developing more effective treatment approaches for eating disorders and weight management.

Neuromodulation and neurofeedback treatments in eating disorders and obesity

PURPOSE OF REVIEW

Psychological interventions are the treatment of choice for most eating disorders; however, significant proportions of patients do not recover with these. Advances in understanding of the neurobiology of eating disorders have led to the development of targeted treatments, such as deep brain stimulation (DBS), noninvasive brain stimulation (NIBS), and neurofeedback. We review the emerging clinical evidence for the use of these interventions in eating disorders and obesity, together with their theoretical rationale. Finally, we reflect on future developments.

RECENT FINDINGS

During the last 20 months, seven case studies/series and seven randomized controlled trials (RCTs) of NIBS or neurofeedback in different eating disorders, obesity, or food craving have appeared. These have largely had promising results. One NIBS trial, using a multisession protocol, was negative. A case series of subcallosal DBS in anorexia nervosa has also shown promise. A search of trial registries identified a further 21 neuromodulation/feedback studies in progress, indicating that neuromodulation/feedback is an area of growing interest.

SUMMARY

At present, neuromodulation and neurofeedback are largely experimental interventions; however, growing understanding of the mechanisms involved, together with the rising number of studies in this area, means that the clinical utility of these interventions is likely to become clearer soon.

Volitional regulation of brain responses to food stimuli in overweight and obese subjects: A real-time fMRI feedback study

Obese subjects who achieve weight loss show increased functional connectivity between dorsolateral prefrontal cortex (dlPFC) and ventromedial prefrontal cortex (vmPFC), key areas of executive control and reward processing. We investigated the potential of real-time functional magnetic resonance imaging (rt-fMRI) neurofeedback training to achieve healthier food choices by enhancing self-control of the interplay between these brain areas. We trained eight male individuals with overweight or obesity (age: 31.8 ± 4.4 years, BMI: 29.4 ± 1.4 kg/m²) to up-regulate functional connectivity between the dlPFC and the vmPFC by means of a four-day rt-fMRI neurofeedback protocol including, on each day, three training runs comprised of six up-regulation and six passive viewing trials. During the up-regulation runs of the four training days, participants successfully learned to increase functional connectivity between dlPFC and vmPFC. In addition, a trend towards less high-calorie food choices emerged from before to after training, which however was associated with a trend towards increased covertly assessed snack intake. Findings of this proof-of-concept study indicate that overweight and obese participants can increase functional connectivity between brain areas that orchestrate the top-down control of appetite for high-calorie foods. Neurofeedback training might therefore be a useful tool in achieving and maintaining weight loss.

Functional Neuroimaging in Obesity Research

Functional neuroimaging is beginning to yield valuable insights into the neurobiological underpinnings of the effects of obesity on neural circuits. Functional magnetic resonance imaging (fMRI), positron emission tomography (PET), and single-photon emission computed tomography (SPECT) studies have been used to identify aberrant activation patterns in regions implicated in reward (e.g., striatum, orbitofrontal cortex, insula), emotion and memory (e.g., amygdala, hippocampus), sensory and motor processing (e.g., insula, precentral gyrus), and cognitive control and attention (e.g., prefrontal cortex, cingulate) in obese individuals. Although a great amount of research using these techniques has already unveiled the influence of different neural response patterns on obesogenic behaviors, in this chapter we will, otherwise, try to highlight the effects of obesity on specific neuronal circuits and discuss recent developments in fMRI-based neurofeedback approaches as an alternative in obesity treatment.

Near-Infrared Spectroscopy based Neurofeedback of Prefrontal Cortex Activity: A Proof-of-Concept Study

Neurofeedback is a promising tool for treatment and rehabilitation of several patient groups. In this proof of principle study, near-infrared spectroscopy (NIRS) based neurofeedback of frontal cortical areas was investigated in healthy adults. Main aims were the assessment of learning, the effects on performance in a working memory (n-back) task and the impact of applied strategies on regulation. 13 healthy participants underwent eight sessions of NIRS based neurofeedback within 2 weeks to learn to voluntarily up-regulate hemodynamic activity in prefrontal areas. An n-back task in pre-/post measurements was used to monitor neurocognitive changes. Mean oxygenated hemoglobin (O2Hb) amplitudes over the course of the sessions as well as during the n-back task were evaluated. 12 out of 13 participants were able to regulate their frontal hemodynamic response via NIRS neurofeedback. However, no systematic learning effects were observed in frontal O2Hb amplitudes over the training course in our healthy sample. We found an impact of applied strategies in only 5 out of 13 subjects. Regarding the n-back task, neurofeedback appeared to induce more focused and specific brain activation compared to pre-training measurement. NIRS based neurofeedback is a feasible and potentially effective method, with an impact on activation patterns in a working memory task. Ceiling effects might explain the lack of a systematic learning pattern in healthy subjects. Clinical studies are needed to show effects in patients exhibiting pathological deviations in prefrontal function.

EEG neurofeedback effects in the treatment of adolescent anorexia nervosa

A pre-post design including 22 females was used to evaluate the effectiveness of neurofeedback in the treatment of adolescent anorexia nervosa. Resting EEG measures and a psychological test-battery assessing eating behavior traits, clinical symptoms, emotionality, and mood were obtained. While both the experimental (n = 10) and control group (n = 12) received their usual maintenance treatment, the experimental group received 10 sessions of individual alpha frequency training over a period of 5 weeks as additional treatment. Significant training effects were shown in eating behavior traits, emotion regulation, and in relative theta power in the eyes closed condition. Although the results are limited due to the small sample size, these are the first empirical data demonstrating the benefits of neurofeedback as a treatment adjunct in individuals with anorexia nervosa.

Neurofeedback: A Comprehensive Review on System Design, Methodology and Clinical Applications

Neurofeedback is a kind of biofeedback, which teaches self-control of brain functions to subjects by measuring brain waves and providing a feedback signal. Neurofeedback usually provides the audio and or video feedback. Positive or negative feedback is produced for desirable or undesirable brain activities, respectively. In this review, we provided clinical and technical information about the following issues: (1) Various neurofeedback treatment protocols i.e. alpha, beta, alpha/theta, delta, gamma, and theta; (2) Different EEG electrode placements i.e. standard recording channels in the frontal, temporal, central, and occipital lobes; (3) Electrode montages (unipolar, bipolar); (4) Types of neurofeedback i.e. frequency, power, slow cortical potential, functional magnetic resonance imaging, and so on; (5) Clinical applications of neurofeedback i.e. treatment of attention deficit hyperactivity disorder, anxiety, depression, epilepsy, insomnia, drug addiction, schizophrenia, learning disabilities, dyslexia and dyscalculia, autistic spectrum disorders and so on as well as other applications such as pain management, and the improvement of musical and athletic performance; and (6) Neurofeedback softwares. To date, many studies have been conducted on the neurofeedback therapy and its effectiveness on the treatment of many diseases. Neurofeedback, like other treatments, has its own pros and cons. Although it is a non-invasive procedure, its validity has been questioned in terms of conclusive scientific evidence. For example, it is expensive, time-consuming and its benefits are not long-lasting. Also, it might take months to show the desired improvements. Nevertheless, neurofeedback is known as a complementary and alternative treatment of many brain dysfunctions. However, current research does not support conclusive results about its efficacy.

A systematic review of the relationship between eating, weight and inhibitory control using the stop signal task

Altered inhibitory control (response inhibition, reward-based inhibition, cognitive inhibition, reversal learning) has been implicated in eating disorders (EDs) and obesity. It is unclear, however, how different types of inhibitory control contribute to eating and weight-control behaviours. This review evaluates the relationship between one aspect of inhibitory control (a reactive component of motor response inhibition measured by the stop signal task) and eating/weight in clinical and non-clinical populations. Sixty-two studies from 58 journal articles were included. Restrained eaters had diminished reactive inhibitory control compared to unrestrained eaters, and showed greatest benefit to their eating behaviour from manipulations of inhibitory control. Obese individuals may show less reactive inhibitory control but only in the context of food-specific inhibition or after executive resources are depleted. Of the limited studies in EDs, the majority found no impairment in reactive inhibitory control, although findings are inconsistent. Thus, altered reactive inhibitory control is related to some maladaptive eating behaviours, and hence may provide a therapeutic target for behavioural manipulations and/or neuromodulation. However, other types of inhibitory control may also contribute. Methodological and theoretical considerations are discussed.

Literature Review of Cognitive Neuroscience and Anorexia Nervosa

Studies published between the beginning of 2013 and May 2015 on the neuropsychological functioning of patients with anorexia nervosa compared with healthy participants framed in the context of the Research Domain Criteria matrix identifies evidence for functional differences in three domains: Negative Valance Systems-negative attentional biases and lack of neural responsivity to hunger; Cognitive Systems-limited congruence between clinical and cognitive performance, poorer non-verbal than verbal performance, altered attentional styles to disorder related stimuli, perceptual processing impairment in discriminating body images, weaknesses in central coherence, set shifting weaknesses at low weight status, decision-making weaknesses, and greater neural resources required for working memory; Systems for Social Processes-patients appear to have a different attentional response to faces, and perception and understanding of self and others. Hence, there is evidence to suggest that patients with anorexia nervosa have a specific neuropsychological performance style across tasks in three domains of functioning. Some current controversies and areas for future development are identified.

Clinical outcomes and neural correlates of 20 sessions of repetitive transcranial magnetic stimulation in severe and enduring anorexia nervosa (the TIARA study): study protocol for a randomised controlled feasibility trial

BACKGROUND

Anorexia nervosa (AN) is a serious mental disorder with multiple comorbidities and complications. In those with a severe and enduring form of the illness (SEED-AN), treatment responsivity is poor and the evidence base limited. Thus, there is a need for novel treatment strategies. This paper describes the theoretical background and protocol of a feasibility randomised controlled trial (RCT) of real versus sham (placebo) therapeutic repetitive transcranial magnetic stimulation (rTMS) in SEED-AN. 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 rTMS in this group of patients, and also to assess the preliminary efficacy and neural correlates of rTMS treatment.

DESIGN

Forty-four adults from the community with a DSM-5 diagnosis of AN, an illness duration>3 years and a previous course of unsuccessful treatment will be randomly allocated to receive 20 sessions of either real or sham rTMS, in a parallel group design. As this is a feasibility study, no primary outcome has been defined and a broad range of outcome variables will be examined. These include weight/body mass index (BMI), eating disorder psychopathology, other psychopathology (for example, depression, anxiety), quality of life, neuropsychological processes (such as self-regulation, attentional bias and food choice behaviour), neuroimaging measures (that is, changes in brain structure or function), tolerability and acceptability of rTMS, and additional service utilisation. The feasibility of conducting a large-scale RCT of rTMS and the appropriateness of rTMS as a treatment for SEED-AN will be evaluated through: 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 assessments). The acceptability and tolerability of the treatment will be assessed via semi-structured interviews.

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. Additionally, results from this study will provide a preliminary indication of the efficacy of rTMS treatment for AN, the neural correlates of the illness, and potential biomarkers of clinical response.

TRIAL REGISTRATION

ISRCTN14329415 . Date of registration: 23 July 2015.

Can an intervention based on a serious videogame prior to cognitive behavioral therapy be helpful in bulimia nervosa? A clinical case study

BACKGROUND

Several studies have highlighted the implications of impulsivity and novelty seeking for both the maintenance and the process of recovery from bulimia nervosa (BN). Cognitive behavioral therapy (CBT) is the treatment of choice for BN, but for some cases, this treatment alone might not be sufficient for reducing the high levels of impulsivity. The paper presents a case report of a patient with BN, examining the effectiveness of using a videogame (VG; Playmancer) as an additional intervention designed to address impulsivity.

DESIGN

Psychometric and neuropsychological measures were collected at baseline. After this assessment, Playmancer was applied prior to CBT, following an "A-B-A-C-A" single case experimental design. Impulsivity levels were assessed with the Conner's Continuous Performance Test II (CPT-II). After the Playmancer treatment, the patient started CBT, and the levels of impulsivity were recorded again. Finally, psychometric and neuropsychological measures were collected after treatment. Weekly frequency of binges and vomiting were also recorded during the entire procedure.

RESULTS

After the VG intervention, psychometric measures such as anxiety levels, impulsivity and novelty seeking decreased. Regarding the neuropsychological measures, impulsivity levels (measured with the CPT-II) progressively decreased throughout the intervention, and an improvement in decision making capacities was observed. Furthermore, the frequency of binges also decreased during and after the VG intervention.

DISCUSSION

This case report suggests that using the Playmancer VG to reduce impulsivity prior to CBT may enhance the final results of the treatment for BN.

Neuroimaging and neuromodulation approaches to study eating behavior and prevent and treat eating disorders and obesity

Functional, molecular and genetic neuroimaging has highlighted the existence of brain anomalies and neural vulnerability factors related to obesity and eating disorders such as binge eating or anorexia nervosa. In particular, decreased basal metabolism in the prefrontal cortex and striatum as well as dopaminergic alterations have been described in obese subjects, in parallel with increased activation of reward brain areas in response to palatable food cues. Elevated reward region responsivity may trigger food craving and predict future weight gain. This opens the way to prevention studies using functional and molecular neuroimaging to perform early diagnostics and to phenotype subjects at risk by exploring different neurobehavioral dimensions of the food choices and motivation processes. In the first part of this review, advantages and limitations of neuroimaging techniques, such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET), single photon emission computed tomography (SPECT), pharmacogenetic fMRI and functional near-infrared spectroscopy (fNIRS) will be discussed in the context of recent work dealing with eating behavior, with a particular focus on obesity. In the second part of the review, non-invasive strategies to modulate food-related brain processes and functions will be presented. At the leading edge of non-invasive brain-based technologies is real-time fMRI (rtfMRI) neurofeedback, which is a powerful tool to better understand the complexity of human brain-behavior relationships. rtfMRI, alone or when combined with other techniques and tools such as EEG and cognitive therapy, could be used to alter neural plasticity and learned behavior to optimize and/or restore healthy cognition and eating behavior. Other promising non-invasive neuromodulation approaches being explored are repetitive transcranial magnetic stimulation (rTMS) and transcranial direct-current stimulation (tDCS). Converging evidence points at the value of these non-invasive neuromodulation strategies to study basic mechanisms underlying eating behavior and to treat its disorders. Both of these approaches will be compared in light of recent work in this field, while addressing technical and practical questions. The third part of this review will be dedicated to invasive neuromodulation strategies, such as vagus nerve stimulation (VNS) and deep brain stimulation (DBS). In combination with neuroimaging approaches, these techniques are promising experimental tools to unravel the intricate relationships between homeostatic and hedonic brain circuits. Their potential as additional therapeutic tools to combat pharmacorefractory morbid obesity or acute eating disorders will be discussed, in terms of technical challenges, applicability and ethics. In a general discussion, we will put the brain at the core of fundamental research, prevention and therapy in the context of obesity and eating disorders. First, we will discuss the possibility to identify new biological markers of brain functions. Second, we will highlight the potential of neuroimaging and neuromodulation in individualized medicine. Third, we will introduce the ethical questions that are concomitant to the emergence of new neuromodulation therapies.

Neuro- and social-cognitive clustering highlights distinct profiles in adults with anorexia nervosa

OBJECTIVE

This study aimed to explore the neuro- and social-cognitive profile of a consecutive series of adult outpatients with anorexia nervosa (AN) when compared with widely available age and gender matched historical control data. The relationship between performance profiles, clinical characteristics, service utilization, and treatment adherence was also investigated.

METHOD

Consecutively recruited outpatients with a broad diagnosis of AN (restricting subtype AN-R: n = 44, binge-purge subtype AN-BP: n = 33 or Eating Disorder Not Otherwise Specified-AN subtype EDNOS-AN: n = 23) completed a comprehensive set of neurocognitive (set-shifting, central coherence) and social-cognitive measures (Emotional Theory of Mind). Data were subjected to hierarchical cluster analysis and a discriminant function analysis.

RESULTS

Three separate, meaningful clusters emerged. Cluster 1 (n = 45) showed overall average to high average neuro- and social- cognitive performance, Cluster 2 (n = 38) showed mixed performance characterized by distinct strengths and weaknesses, and Cluster 3 (n = 17) showed poor overall performance (Autism Spectrum disorder (ASD) like cluster). The three clusters did not differ in terms of eating disorder symptoms, comorbid features or service utilization and treatment adherence. A discriminant function analysis confirmed that the clusters were best characterized by performance in perseveration and set-shifting measures.

DISCUSSION

The findings suggest that considerable neuro- and social-cognitive heterogeneity exists in patients with AN, with a subset showing ASD-like features. The value of this method of profiling in predicting longer term patient outcomes and in guiding development of etiologically targeted treatments remains to be seen.

The Promise of Neurotechnology in Clinical Translational Science

Neurotechnology is broadly defined as a set of devices used to understand neural processes and applications that can potentially facilitate the brain's ability to repair itself. In the past decade, an increasingly explicit understanding of basic biological mechanisms of brain-related illnesses has produced applications that allow a direct yet noninvasive method to index and manipulate the functioning of the human nervous system. Clinical scientists are poised to apply this technology to assess, treat, and better understand complex socioemotional processes that underlie many forms of psychopathology. In this review, we describe the potential benefits and hurdles, both technical and methodological, of neurotechnology in the context of clinical dysfunction. We also offer a framework for developing and evaluating neurotechnologies that is intended to expedite progress at the nexus of clinical science and neural interface designs by providing a comprehensive vocabulary to describe the necessary features of neurotechnology in the clinic.

Provocation of symmetry/ordering symptoms in Anorexia nervosa: a functional neuroimaging study

Anorexia nervosa (AN), obsessive–compulsive disorder (OCD), and obsessive–compulsive personality disorder (OCPD) are often co-morbid; however, the aetiology of such co-morbidity has not been well investigated. This study examined brain activation in women with AN and in healthy control (HC) women during the provocation of symmetry/ordering-related anxiety. During provocation, patients with AN showed more anxiety compared to HCs, which was correlated with the severity of symmetry/ordering symptoms. Activation in the right parietal lobe and right prefrontal cortex (rPFC) in response to provocation was reduced in the AN group compared with the HC group. The reduced right parietal activation observed in the AN group is consistent with parietal lobe involvement in visuospatial cognition and with studies of OCD reporting an association between structural abnormalities in this region and the severity of ‘ordering’ symptoms. Reduced rPFC activation in response to symmetry/ordering provocation has similarities with some, but not all, data collected from patients with AN who were exposed to images of food and bodies. Furthermore, the combination of data from the AN and HC groups showed that rPFC activation during symptom provocation was inversely correlated with the severity of symmetry/ordering symptoms. These data suggest that individuals with AN have a diminished ability to cognitively deal with illness-associated symptoms of provocation. Furthermore, our data also suggest that symptom provocation can progressively overload attempts by the rPFC to exert cognitive control. These findings are discussed in the context of the current neurobiological models of AN.

A physiological perspective on the neuroscience of eating

I present the thesis that 'being physiological,' i.e., analyzing eating under conditions that do not perturb, or minimally perturb, the organism's endogenous processes, should be a central goal of the neuroscience of eating. I describe my understanding of 'being physiological' based on [i] the central neural-network heuristic of CNS function that traces back to Cajal and Sherrington, [ii] research on one of the simpler problems in the neuroscience of eating, identification of endocrine signals that control eating. In this context I consider natural meals, physiological doses and ranges, and antagonist studies. Several examples involve CCK. Next I describe my view of the cutting edge in the molecular neuroscience of eating as it has evolved from the discovery of leptin signaling through the application of optogenetic and pharmacogenetic methods. Finally I describe some novel approaches that may advance the neuroscience of eating in the foreseeable future. I conclude that [i] the neuroscience of eating may soon be able to discern 'physiological' function in the operation of CNS networks mediating eating, [ii] the neuroscience of eating should capitalize on methods developed in other areas of neuroscience, e.g., improved methods to record and manipulate CNS function in behaving animals, identification of canonical regional circuits, use of population electrophysiology, etc., and [iii] subjective aspects of eating are crucial aspects of eating science, but remain beyond mechanistic understanding.