Disgust proneness and associated neural substrates in obesity

Disgust as a transdiagnostic index of mental illness: A narrative review of clinical populations

Disgust is a basic emotion of rejection, providing an ancestral defensive mechanism against illness. Based on research that documents altered experiences of disgust across several psychopathological conditions, we conducted a narrative review to address the hypothesis that altered disgust may serve as a transdiagnostic index of mental illness. Our synthesis of the literature from past decades suggests that, compared to healthy populations, patients with mental disorders exhibit abnormal processing of disgust in at least one of the analyzed dimensions. We also outline evidence of alterations in brain areas relevant to disgust processing, such as the insula and the interconnected limbic network. Overall, we provide preliminary support for the hypothesis that altered disgust processing may serve as a transdiagnostic index of mental illness.

Adiposity affects emotional information processing

Obesity is a worldwide epidemic associated with severe health and psychological wellbeing impairments expressed by an increased prevalence of affective disorders. Emotional dysfunction is important due to its effect on social performance. The aim of the present narrative review is to provide a general overview of human research exploring emotional information processing in overweight and obese people. Evidence suggests that obesity is associated with an attenuation of emotional experience, contradictory findings about emotion recognition, and scarce research about automatic emotional information processing. Finally, we made some concluding considerations for future research on emotional information processing in overweight and obese people.

Time estimation and passage of time judgment predict eating behaviors during COVID-19 lockdown

Poor eating habits often lead to health concerns. While mental health conditions such as stress and anxiety have been linked as predictors for eating behaviors, cognitive factors may also contribute to eating practices during the early stages of the mandatory COVID-19 lockdown. In the current study, participants responded to a survey that asked them to judge the passing of time (PoTJ) and to produce short intervals (via a time production task) as an index of the internal clock speed. Additionally, they responded to questions about snacking frequency and the tendency to overeat during lockdown. We observed that those who judged time to pass slowly also reported a greater tendency to snack and overeat during the pandemic. Additional analysis also revealed that the effect of PoTJ on snacking is moderated by the internal clock speed such that those who felt time was passing by slowly, and in combination with a faster internal clock (as indexed by shorter duration production), had a greater tendency to snack. The results suggest that different aspects of temporal cognition play potential roles in influencing different types of eating behaviors. Our findings therefore have implications for eating disorders, along with the potential of time-based intervention or behavioral modification approaches.

Meat disgust is negatively associated with meat intake - Evidence from a cross-sectional and longitudinal study

Meat consumption is increasingly seen as unsustainable, unhealthy, and unethical. Understanding what factors help people reduce their meat intake is urgently needed. One such factor is meat disgust, a feeling reported by many vegetarians, and which could be a promising basis for meat reduction interventions. However, meat disgust and its impact on meat consumption is poorly understood. We examined meat disgust and its role in vegetarianism and reducing meat intake in a cross-sectional and longitudinal online study. We measured self-reported meat consumption, meat disgust (by self-report and Implicit Association Test), meat liking, self-control, and disgust sensitivity in N = 711 adults (57% omnivores, 28% flexitarians, 15% vegetarians) recruited from a community cohort. Results showed that 73% of vegetarians can be classified as 'meat disgusted', and that meat disgust predicted meat intake better than self-control in omnivores and flexitarians at baseline. Following up a sub-sample of participants (N = 197) after six months revealed that changes in meat intake over time were also associated with changes in meat disgust. This is the first study to quantify the impact of meat disgust on (changes in) meat consumption and its prevalence in the vegetarian and the general population. Our findings advance research into meat disgust and encourage the development of disgust-based interventions to reduce meat intake.

Early changes in neural circuit function engaged by negative emotion and modified by behavioural intervention are associated with depression and problem-solving outcomes: A report from the ENGAGE randomized controlled trial

BACKGROUND

Depression exerts a staggering toll that is worsened with co-occurring chronic conditions such as obesity. It is imperative to develop more effective interventions for depression and to identify objective and biological plausible neural mechanisms to understand intervention outcomes. The current study uses functional neuroimaging to determine whether a behavioural intervention changes the negative affect circuit and whether these changes relate to subsequent improvements in both symptom and problem-solving outcomes in depressed patients with co-occurring obesity.

METHODS

This study ('ENGAGE') was a pre-planned element of the randomized controlled trial, 'RAINBOW' (ClinicalTrials.gov NCT02246413). 108 depressed patients with obesity were randomized to receive an integrated collaborative care intervention (I-CARE) or usual care. Participants underwent functional neuroimaging using an established facial emotion task at baseline and two months (coinciding with the first two months of intervention focused on problem-solving therapy ('PST')). Amygdala, insula and anterior cingulate cortex activation was extracted using pre-planned definitions and standardized methods. The primary health and behavioural outcomes were depression symptom severity and problem-solving ability respectively, assessed at baseline, the main 6-month outcome point and at 12-month follow up. Mediation analyses used an intent-to-treat approach.

FINDINGS

PST, relative to usual care, reduced amygdala activation engaged by threat stimuli at two months. This reduction mediated subsequent improvements in depression severity in an intervention-dependent manner. PST did not change insula activation at two months but did temper the strength of the relationship between insula activation and improvements in problem-solving ability.

INTERPRETATION

The negative affect circuit may be an important neural target and potential mediator of PST in patients with comorbid obesity.

FUNDING

US National Institutes of Health/National Heart Lung and Blood Institute R01 HL119453 and UH2/UH3 HL132368.

Food Preferences and Obesity

Obesity is a multifactorial disease with several potential causes that remain incompletely understood. Recent changes in the environment, which has become increasingly obesogenic, have been found to interact with individual factors. Evidence of the role of taste responsiveness and food preference in obesity has been reported, pointing to a lower taste sensitivity and a higher preference and intake of fat and, to a lesser extent, sweet foods in obese people. Studies in the last decades have also suggested that individual differences in the neurophysiology of food reward may lead to overeating, contributing to obesity. However, further studies are needed to confirm these findings. In fact, only a limited number of studies has been conducted on large samples, and several studies were conducted only on women. Larger balanced studies in terms of sex/gender and age are required in order to control the confounding effect of these variables. As many factors are intertwined in obesity, a multidisciplinary approach is needed. This will allow a better understanding of taste alteration and food behaviours in obese people in order to design more effective strategies to promote healthier eating and to prevent obesity and the related chronic disease risks.

Food Disgust Scale: Spanish Version

INTRODUCTION

The Food Disgust Scale (FDS) was recently developed and validated in Swiss adult population. This study aims to: (1) validate the FDS for the first time in a Spanish-speaking Mexican population, (2) correlate food disgust sensitivity with picky eating measures, and (3) explore the association between food disgust sensitivity and body mass index (BMI).

MATERIALS AND METHODS

A Spanish version of the FDS (FDS-Sp) and its short version (FDS-Sp short) were tested with confirmatory factor analysis (CFA) in order to test the original item/factor structure. Bivariate correlations were performed to determine the association between FDS-Sp/FDS-Sp short scores and picky eating. Lastly, hierarchical linear regression analysis was carried out to determine the relationship between food disgust sensitivity and BMI.

RESULTS

The factor structure of the FDS was replicated and acceptable internal consistency values were observed for FDS-Sp subscales (α varied between 0.781 and 0.955). Moreover, FDS-Sp subscales and FDS-Sp short were correlated with picky eating. Higher score in VEGI subscale of the FDS-Sp was a significant predictor for higher BMI, explaining 4% of the variance.

CONCLUSION

FDS-Sp is a useful, reliable and robust psychometric instrument to measure the sensitivity to unpleasant food situations in a Mexican adult Spanish-speaking population. A relationship between food disgust sensitivity and picky eating, selective eating behaviors and neophobia in Mexicans was confirmed. BMI is multifactorial and only one subscale of FDS-Sp is a significant predictor for BMI status. These results are helpful to continue exploring food disgust in diverse populations.

Food-Specific Inhibitory Control Mediates the Effect of Disgust Sensitivity on Body Mass Index

Disgust is an emotion that drives food avoidance. People vary in their responses to disgust, which is captured by their disgust sensitivity. Disgust sensitivity is clinically significant because it can influence eating behaviors, and indirectly people's body mass index (BMI). Inhibitory control can also influence BMI through the role that such reflective abilities play in governing food intake. In this study, we relied on neural models of disgust to suggest that disgust and inhibitory control are intertwined, and that inhibitory control facilitates the translation of disgust sensitivity into BMI. Mediation analyses applied to 46 subjects, including 29 normal body weight [BMI = 18.34 kg/m² (SD = 1.58)] and 17 overweight/obese [BMI = 26.03 kg/m² (SD = 2.58)] subjects, were used to test the hypothesis. Subjects completed the Chinese version of the Disgust Scale-Revised, and an inhibition control test (Food-Specific Stop-Signal Task). There were negative correlations between the disgust sensitivity score (DS) and body mass index (BMI), and between DS and stop-signal reaction time (SSRT). Moreover, BMI was positively correlated with SSRT. The mediation model results showed that disgust sensitivity was associated with BMI and that this relationship was mediated via inhibition control. There was no significant effect of DS on BMI, while the effect of SSRT on BMI was significant. This suggested that the effect of disgust sensitivity on BMI was fully mediated through food-specific inhibitory control. This supports our hypothesis that BMI is affected by disgust sensitivity and that this relationship is mediated by inhibition control. These findings reveal a key mechanism that underlies disgust sensitivity-BMI association and point to future research and potential interventions aimed at food intake management.

Time is overestimated in obesity: A cohort study

Food addiction and high impulsivity are common traits in obesity. In accordance with the evidence that time is overestimated in patients with a history of impulsivity and/or drug addiction, we tested the hypothesis that duration is overestimated in obesity. A total of 92 obese participants and 182 healthy controls completed a timing task of visual stimuli. In line with our prediction, obese participants overestimated the duration of the displayed visual stimuli than controls. Our result has potential clinical implications in the field of obesity, as it suggests a potential contribution of this cognitive dysfunction in the emergence and maintenance of obesity-related behaviour.

Core, social and moral disgust are bounded: A review on behavioral and neural bases of repugnance in clinical disorders

Disgust is a multifaceted experience that might affect several aspects of life. Here, we reviewed research on neurological and psychiatric disorders that are characterized by abnormal disgust processing to test the hypothesis of a shared neurocognitive architecture in the representation of three disgust domains: i) personal experience of 'core disgust'; ii) social disgust, i.e., sensitivity to others' expressions of disgust; iii) moral disgust, i.e., sensitivity to ethical violations. Our review provides some support to the shared neurocognitive hypothesis and suggests that the insula might be the "hub" structure linking the three domains of disgust sensitivity, while other brain regions may subserve specific facets of the multidimensional experience. Our review also suggests a role of serotonin core and moral disgust, supporting "neo-sentimentalist" theories of morality, which posit a causal role of affect in moral judgment.

Voxel-based morphometry of disgust sensitivity

Background: Difficulties with the regulation of negative affect have been extensively studied in neuroimaging research. However, dysregulation of a specific emotion, disgust, has hardly been investigated. In the present study, we used voxel-based morphometry to identify whether gray matter volume (GMV) of frontal regions is correlated with personality traits associated with general and disgust-specific emotion regulation difficulties.

Method: We analyzed T1-weighted images of 49 females (mean age = 22.8 years, SD = 3.2). The women rated their disgust sensitivity (DS) (temporally stable tendency to experience disgust as uncontrollable and extremely aversive) as well as general difficulties with emotion regulation.

Results: DS and general emotion regulation deficits were positively associated with a heightened GMV of the orbitofrontal cortex. DS additionally showed a negative association with GMV of the medial prefrontal cortex.

Conclusion: The present study revealed shared and distinct contributions of frontal brain regions to disgust-specific and general emotion regulation difficulties.

Extremes of eating are associated with reduced neural taste discrimination

OBJECTIVE

Eating disorders are severe psychiatric disorders of unknown etiology. Understanding how neuronal function affects food choices could help personalize treatment based on brain function. Here we wanted to determine whether disordered eating behavior is associated with alterations in the primary taste cortex's ability to classify taste stimuli, which could interfere with taste reward processing.

METHOD

One-hundred and six women, 27 healthy comparison (age 26.15 ± 6.95 years), 21 with restricting-type anorexia nervosa (AN; age 23.10 ± 6.14 years), 19 recovered from restricting-type AN (recovered AN; age 26.95 ± 5.31 years), 20 with bulimia nervosa (BN; age 25.15 ± 5.31 years), and 19 with obesity (age 28.16 ± 8.13 years), received sucrose, control solution or no taste stimulation during functional magnetic resonance brain imaging. Multivariate Bayesian pattern analysis (decoding) and cross-validation tested taste classification accuracy (adjusted for comorbidity, medication use, taste perception, interoception, and brain activation volume).

RESULTS

For sucrose versus control solution, classification accuracy differed (F = 2.53, P < 0.041). Post hoc tests indicated higher classification accuracy in healthy comparison compared to women with AN (P < 0.016) or obesity (P < 0.027), and in recovered AN as compared to AN (P < 0.016) or obesity (P < 0.047) groups. Taste stimulation resulted in sparse insula voxel activation across all groups.

DISCUSSION

Reduced classification accuracy across stimuli in women with AN or obesity could indicate low brain encoding discrimination of stimulus quality, which could contribute to altered reward activation and eating drive that is not adjusted to nutritional needs. This deficit appears to normalize with recovery from AN, but adjusting food flavor intensity could aid in the treatment of individuals with AN or obesity. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2016; 49:603-612).