Processing of visual food cues during bitter taste perception in female patients with binge-eating symptoms: A cross-modal ERP study

The Effect of Accelerated Continuous Theta Burst Stimulation on Weight Loss in Overweight Individuals With Schizophrenia: A Double-Blind, Randomized, Sham-Controlled Clinical Trial

BACKGROUND AND HYPOTHESIS

Obesity is a common comorbidity in individuals with schizophrenia and is associated with poor clinical outcomes. At present, there are limited effective approaches for addressing this issue. We conducted a double-blind, randomized, sham-controlled clinical trial to investigate the efficacy of noninvasive magnetic stimulation techniques in reducing obesity in individuals with schizophrenia.

STUDY DESIGN

Forty overweight individuals with schizophrenia were recruited and randomly assigned to receive either the active or sham intervention. The active group received 50 accelerated continuous theta burst stimulation (cTBS) sessions over the left primary motor area (M1), while the sham group received sham stimulation. The primary outcomes were the change in body weight and body mass index (BMI), and the secondary outcomes were the psychiatric symptoms, eating behavior scales, metabolic measures, and electrophysiological to food picture stimuli.

STUDY RESULTS

The study demonstrated a significant decrease in body weight and BMI after the intervention selectively in the active group (mean = -1.33 kg, P = .002), and this improvement remained at the 1-month follow-up (mean = -2.02 kg, P = .008). The score on the Barratt Impulsivity Scale (mean = -1.78, P = 0.036) decreased in the active group and mediated the effect of accelerated cTBS on body weight. In the food picture cue electroencephalograph task, the late positive potential component, which is related to motivated attention and emotional processing, decreased in frontal brain regions and increased in posterior regions after the active intervention.

CONCLUSIONS

The accelerated cTBS may offer a promising approach for treating obesity in individuals with schizophrenia. Further research with a larger sample size or individualized stimulation protocol should be promising.

TRIAL REGISTRATION

Clinical trial registered with clinicaltrials.gov (NCT05086133).

The potential application of event-related potentials to enhance research on reward processes in eating disorders

OBJECTIVE

Reward-related processes have been posited as key mechanisms underlying the onset and persistence of eating disorders, prompting a growing body of research in this area. Existing studies have primarily utilized self-report, behavioral, and functional magnetic resonance imaging measures to interrogate reward among individuals with eating disorders. However, limitations inherent in each of these methods (e.g., poor temporal resolution) may obscure distinct neurocognitive reward processes, potentially contributing to underdeveloped models of reward dysfunction within eating disorders. The temporal precision of event-related potentials (ERPs), derived from electroencephalography, may thus offer a powerful complementary tool for elucidating the neurocognitive underpinnings of reward. Indeed, a considerable amount of research in other domains of psychopathology (e.g., depression, substance use disorders), as well as studies investigating food reward among non-clinical samples, highlights the utility of ERPs for probing reward processes. However, no study to date has utilized ERPs to directly examine reward functioning in eating disorders.

METHODS

In this paper, we review evidence underscoring the clinical utility of ERP measures of reward, as well as a variety of reward-related tasks that can be used to elicit specific ERP components with demonstrated relevance to reward processing. We then consider the ways in which these tasks/components may be used to help answer a variety of open questions within the eating disorders literature on reward.

RESULTS/DISCUSSION

Given the promise of ERP measures of reward to the field of eating disorders, we ultimately hope to spur and guide research in this currently neglected area.

PUBLIC SIGNIFICANCE

Abnormalities in reward functioning appear to contribute to eating disorders. Event-related potentials (ERPs) offer temporally precise measures of neurocognitive reward processing and thus may be important tools for understanding the relationship between reward and disordered eating. However, research in this area is currently lacking. This paper attempts to facilitate the use of ERPs to study reward among individuals with eating disorders by reviewing the relevant theories and methods.

Capsaicin-induced pain increases neural responses to low-calorie non-spicy food cues: An ERP study

Capsaicin, the main spicy ingredient in chili, can activate pain receptors on the human tongue and skin. Although some studies have determined that pain influenced preference for high-calorie foods, little is known whether pain can modulate the individuals' preference for spicy foods and its neural mechanisms. After 30 participants underwent painful (topical capsaicin cream) and control (hand cream) treatments, an event-related potential (ERP) study was conducted to investigate the modulation of capsaicin-induced pain on food preference with food images. Results showed that both P3 and late positive potential (LPP) amplitudes during the painful treatment were significantly larger than those during the control treatment for low-calorie non-spicy food cues. However, for the other three categories of food cues, there were no significant differences between the two treatments. The present study suggests that capsaicin-induced pain increases individuals' neural processing of low-calorie non-spicy food cues, which provides empirical evidence on the relationship between pain and neural responses to food cues to help optimize dietary interventions for patients experiencing pain.

Disgust and Self-Disgust in Eating Disorders: A Systematic Review and Meta-Analysis

Disgust and self-disgust are aversive emotions which are often encountered in people with eating disorders. We conducted a systematic review and meta-analysis of disgust and self-disgust in people with eating disorders using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The systematic review of the literature revealed 52 original research papers. There was substantial heterogeneity regarding the research question and outcomes. However, we found 5 articles on disgust elicited by food images, 10 studies on generic disgust sensitivity, and 4 studies on self-disgust, and we proceeded to a meta-analytic approach on these studies. We found that women with eating disorders have significantly higher momentary disgust feelings in response to food images (1.32; 95% CI 1.05, 1.59), higher generic disgust sensitivity (0.49; 95% CI 0.24, 0.71), and higher self-disgust (1.90; 95% CI 1.51, 2.29) compared with healthy controls. These findings indicate the potential clinical relevance of disgust and self-disgust in the treatment of eating disorders.

Using event-related potentials to study food-related cognition: An overview of methods and perspectives for future research

Electroencephalography (EEG), and the measure of event-related potentials (ERPs) in particular, are useful methods to study the cognitive and cerebral mechanisms underlying the perception and processing of food cues. Further research on these aspects is necessary to better understand how cognitive functioning may influence food choices in different populations (e.g. obese individuals, individuals with eating disorders). To help researchers in designing future studies, this article provides an overview of the methods used in the current literature on ERPs and food-related cognition. Several methodological aspects are explored to outline interesting perspectives for future research, including discussions on the main experimental tasks used, the cognitive functions assessed (e.g. inhibitory control, attentional processing), the characteristics of the participants recruited (e.g. weight status, eating behaviors), and the stimuli selected (e.g. food pictures, odors). The issues generated by some of these methodological choices are discussed, and a few guidelines are provided.

A Systematic Review of Electrophysiological Findings in Binge-Purge Eating Disorders: A Window Into Brain Dynamics

Binge-purge eating disorders (BP-ED), such as bulimia nervosa and binge eating disorder, may share some neurobiological features. Electroencephalography (EEG) is a non-invasive measurement modality that may aid in research and diagnosis of BP-ED. We conducted a systematic review of the literature on EEG findings in BP-ED, seeking to summarize and analyze the current evidence, as well as identify shortcomings and gaps to inform new perspectives for future studies. Following PRISMA Statement recommendations, the PubMed, Embase, and Web of Science databases were searched using terms related to “electroencephalography” and “binge-purge” eating disorders. Of 555 articles retrieved, 15 met predefined inclusion criteria and were included for full-text analysis. Eleven studies investigated EEG by means of event-related potentials (ERP) in BP-ED individuals: 7 using eating disorder-related stimuli (i.e., food, body image) and 4 using non-eating disorder-related stimuli (i.e., facial expressions or auditory clicks). These studies found significant differences in the N200, P200, P300, and LPP components in BP-ED participants compared to controls, indicating that this population exhibits impairments in selective attention, attentional allocation/processing, and allocation of motivational or emotion-based attention. Five studies investigated EEG using frequency analysis; reporting significant differences in beta activity in fronto-temporal and occipito-temporo-parietal areas in BP-ED individuals compared to controls, revealing a dysfunctional brain network. However, the small number of studies, the heterogeneity of samples, study paradigms, stimulus types, and the lack of an adequate assessment of neuropsychological parameters are some limitations of the current literature. Although some EEG data are promising and consistent with neuroimaging and neuropsychological findings in individuals with BP-ED, future studies need to overcome current methodological shortcomings.

Incentive sensitization in binge behaviors: A mini review on electrophysiological evidence

Introduction

Binge behavior not only refers to the consumption of substances such as alcohol or food, but is also used in relation to gaming, watching and gambling. Dependent on context it makes for a widespread, benign recreational activity or can pose a serious mental health problem with deleterious consequences. Incentive sensitization theory describes the attribution of salience towards stimuli strongly associated with dopamine-mediated reward as a result of repeated consumption. The sensitized neural networks cause cue-triggered craving and excessive desire, but thus, this mechanism may also be applicable to stimulus-induced behaviors not associated with classical withdrawal symptoms. Event-related potentials (ERP) are a useful method of examining motivated attention towards incentive stimuli. This mini review aims to synthesize ERP findings from different types of binge behaviors in order to compare cue-reactivity to incentive stimuli.

Methods

Studies investigating binge drinking, binge eating as well as binge watching, gaming and gambling were screened. To limit the influence of concurrent task demands, ERP studies applying picture viewing paradigms with incentive stimuli were selected.

Results

Across binge behaviors, evidence on altered mid-latency ERPs has been mixed. However, studies investigating later stages of attentional processes more consistently find enlarged P300 and late positive potentials (LPP) amplitudes to relevant cues.

Conclusion

An altered attentional processing of incentive stimuli reflecting motivated attention is in line with incentive sensitization theory. Considering the limited number of studies, especially regarding binge behaviors not involving substances, more research is needed to attain a more thorough understanding of incentive sensitization across binge behaviors.

Disgust Propensity and the Bitter Aftertaste Response

Introduction

A high level of disgust propensity (the general tendency to respond with the emotion of disgust to any given situation) is associated with an increased sensitivity to bitter taste. The present study examined the relationship between disgust propensity and the sensitivity to bitter aftertaste.

Methods

A total of 200 women rinsed their mouth with concentrated wormwood tea (Artemisia absinthium). The resulting aftertaste was evaluated (intensity of bitterness and disgust) every 15 s for 10 min. A multiple linear regression analysis was calculated to capture the association between aftertaste ratings and affective variables (e.g., disgust propensity, depression symptoms).

Results

Higher disgust propensity was associated with higher initial disgust ratings and faster reduction of disgust over time. Higher depression scores were associated with a slower disgust reduction.

Conclusion

We demonstrated that affective variables predict the temporal course of the wormwood aftertaste response. Having a higher disgust propensity was associated with a shortened disgust recovery.

Implications

A shortened disgust recovery may be adaptive because it enables faster processing of new disgust stimuli.

Brain Imaging of Taste Perception in Obesity: a Review

PURPOSE OF REVIEW

We summarize neuroimaging findings related to processing of taste (fat, salt, umami, bitter, and sour) in the brain and how they influence hedonic responses and eating behaviors and their role in obesity.

RECENT FINDINGS

Neuroimaging studies in obese individuals have revealed alterations in reward/motivation, executive control/self-regulation, and limbic/affective circuits that are implicated in food and drug addiction. Psychophysical studies show that sensory properties of food ingredients may be associated with anthropometric and neurocognitive outcomes in obesity. However, few studies have examined the neural correlates of taste and processing of calories and nutrient content in obesity. The literature of neural correlated of bitter, sour, and salty tastes remains sparse in obesity. Most published studies have focused on sweet, followed by fat and umami taste. Studies on calorie processing and its conditioning by preceding taste sensations have started to delineate a dynamic pattern of brain activation associated with appetition. Our expanded understanding of taste processing in the brain from neuroimaging studies is poised to reveal novel prevention and treatment targets to help address overeating and obesity.

Neural responses to food stimuli among individuals with eating and weight disorders: a systematic review of event-related potentials

A systematic review was conducted to investigate event-related potentials (ERPs) in response to food and non-food stimuli among individuals with eating and weight disorders. Limiting the search to studies that have analysed ERPs relating to motivated attention and inhibitory control, 19 research papers were extracted from a systematic search in PubMed, Ovid, and Web of Science (2000-2018). An enhanced attentional bias towards food over non-food images (as indexed by P3(00) and LPP amplitudes) was evident for all populations. Individuals with binge eating disorder showed an enhanced attentional response to food cues compared to healthy controls. Inhibitory control-related ERP components (N2(00) and P3a) increased during food-specific no-go trials, but did not differentiate overweight from 'healthy' weight groups. The N2 amplitude to food pictures were positively correlated with caloric intake and food craving among individuals with obesity and binge eating disorder, respectively, while P3(00) was sensitive to hunger levels among overweight and obese females. The heterogeneity of stimuli/paradigms adopted, component timescales extracted, ERPs analysed, and data presented has challenged this review's ability to produce a robust synthesis of results. Some recommendations for future research are discussed.

Tracking Economic Value of Products in Natural Settings: A Wireless EEG Study

Economic decision making refers to the process of individuals translating their preference into subjective value (SV). Little is known about the dynamics of the neural processes that underpin this form of value-based decision making and no studies have investigated these processes outside of controlled laboratory settings. The current study investigated the spatio-temporal dynamics that accompany economic valuation of products using mobile electroencephalography (EEG) and eye tracking techniques. Participants viewed and rated images of household products in a gallery setting while EEG and eye tracking data were collected wirelessly. A Becker-DeGroot-Marschak (BDM) auction task was subsequently used to quantify the individual's willingness to pay (WTP) for each product. WTP was used to classify products into low, low medium, high medium and high economic value conditions. Eye movement related potentials (EMRP) were examined, and independent component analysis (ICA) was used to separate sources of activity from grand averaged EEG data. Four independent components (ICs) of EMRPs were modulated by WTP (i.e., SV) in the latency range of 150-250 ms. Of the four value-sensitive ICs, one IC displayed enhanced amplitude for all value conditions excluding low value, and another IC presented enhanced amplitude for low value products only. The remaining two value-sensitive ICs resolved inter-mediate levels of SV. Our study quantified, for the first time, the neural processes involved in economic value based decisions in a natural setting. Results suggest that multiple spatio-temporal brain activation patterns mediate the attention and aversion of products which could reflect an early valuation system. The EMRP parietal P200 component could reflect an attention allocation mechanism that separates the lowest-value products (IC7) from products of all other value (IC4), suggesting that low-value items are categorized early on as being aversive. While none of the ICs showed linear amplitude changes that parallel SV's of products, results suggest that a combination of multiple components may sub-serve a fine-grained resolution of the SV of products.