Being impulsive and obese increases susceptibility to speeded detection of high-calorie foods

Exploring the impact of impulsivity and indulgent consumption on eating patterns of Chinese consumers

There is a growing concern about unhealthy eating habits and their impact on public health, underscoring the importance of research to understand its determinants and encourage healthy food habits. Using behavioural economic insights in researching dietary habit offer advantages beyond the scope of observational studies. Therefore, this paper examines impulsivity, self-indulgence, prudence and their associations with an individual's eating habits and body mass index (BMI). Data were collected from a sample of 487 Chinese participants. Most participants (88%) had good eating habits based on the Healthy Eating Assessment score. The findings of a logistic regression analysis investigating the determinants of individual dietary behaviour based on participants' self-rating of their overall dietary habits indicate that consumers who showed temporal impulsivity for favourite food tend to have poorer habits of eating healthy foods. The results of a multiple linear regression examining the factors that influence eating habits from a composite score of the Healthy Eating Assessment indicate that the score is better with temporal impulsivity for healthy food and poor with temporal impulsivity for unhealthy food. Further, the score decreases with impulsivity measured as low self-control. The control variables, age and gender, are also significant. The findings of a linear regression analysis exploring the determinants of BMI and their association with impulsivity, self-indulgence and prudence indicate that individuals with higher impulsivity measured as low self-control are mostly in the higher BMI category. These findings are important for designing and implementing public health initiatives to promote healthier dietary habits.

Self-Regulation in Eating Behaviors: The Role of Executive Function in Response to Food Stimuli

Human nutrition is characterized by both automatic and self-regulated processes. One of the dimensions that may be employed in monitoring eating behaviors is the cognitive control played by the executive functions (EFs). The role of EFs in affecting eating behaviors has been assessed in empirical studies, but further analyses are needed in a current society characterized by a food-abundant environment. Accordingly, this study attempted to evaluate the association between weight status and executive functions in response to food-related stimuli. One hundred and forty-four young adults took part in the study (25.7% in overweight condition). The participants completed a set of computerized cognitive tasks to assess cognitive and motor inhibition and working memory in two different conditions: (i) classic versions of the tasks and (ii) modified versions with food cues. The results indicate that food stimuli may influence executive performance and that there is an association between food cue-related executive functioning, particularly in the domain of motor inhibition, and working memory. These results suggest that self-regulation in nutrition may involve executive control. Although further studies are needed, this work suggests the importance of a multidimensional perspective in the analysis of eating behaviors and the relevance of EFs in monitoring our approach to food stimuli in an environmental context.

Association of Overweight and Obesity with Impaired Executive Functioning in Mexican Adolescents: The Importance of Inhibitory Control

Overweight and obesity are major public health issues worldwide, including in Mexico, particularly among adolescents. This study aimed to analyze the associations between nutritional status and impaired executive function (EF) in Mexican adolescents. A case-control study was conducted with 98 male and female adolescents, categorized into normal weight and overweight/obese groups based on body mass index. EF was assessed using the BANFE-2 test. The prevalence of overweight and obesity was 54.3%. The EF assessment revealed that 82.45% of the overweight/obese group exhibited mild-to-severe impairment, compared to only 36.58% in the normal weight group (X2 = 21.69, p < 0.0001). In the inhibitory control assessment, adolescents with overweight and obesity performed worse than their normal-weight counterparts. Specifically, females with overweight/obesity scored lower than females with normal weight on the risk-benefit processing test. The risk of severe EF impairment significantly increased with the presence of overweight/obesity (OR = 7.8, p < 0.0001). These findings indicate that EF, particularly inhibitory control and risk-benefit processing, is impaired in adolescents with overweight or obesity.

Inhibition and shifting across the weight status spectrum

Executive functioning (EF) is of major interest in the study of cognitive factors involved in obesity. Among EF, shifting is related to behavioral flexibility, and inhibition to the ability to refrain from impulsive behavior. A deficit in those two EF could predict individual difficulties to maintain a healthy lifestyle. Weak evidence of deficits in shifting and inhibition in individuals of higher Body Mass Index (BMI) have been observed. The objective was to clarify the relationship between inhibition and shifting regarding weight status group differences in healthy adults. Two neuropsychological tests from the Test of Attentional Performance (TAP) battery were used to measure EF performance of three groups of men and women: normal-weight (NW, n = 38), overweight (OW, n = 40) and obesity (OB, n = 37). The results show that individuals with higher BMI have lower inhibition capacities and that classically used weight status categories might not capture cognitive variability. No differences in shifting were observed concerning weight status nor BMI. This paper provides new insights on cognitive factors in obesity by presenting data from healthy individuals with overweight and obesity. The results support that assessing inhibition capacities might be of interest in a clinical setting for patients with difficulties to lose weight.

Role of the CB2 Cannabinoid Receptor in the Regulation of Food Intake: A Systematic Review

The CB2 cannabinoid receptor has been found in brain areas that are part of the reward system and has been shown to play a role in food intake regulation. Herein, we conducted a systematic review of studies assessing the role of the CB2 receptor in food intake regulation. Records from the PubMed, Scopus, and EBSCO databases were screened, resulting in 13 studies that were used in the present systematic review, following the PRISMA guidelines. A risk of bias assessment was carried out using the tool of the Systematic Review Center for Laboratory Animal Experimentation (SYRCLE). The studies analyzed used two main strategies: (1) the intraperitoneal or intracerebroventricular administration of a CB2 agonist/antagonist; and (2) depletion of CB2 receptors via knockout in mice. Both strategies are useful in identifying the role of the CB2 receptor in food intake in standard and palatable diets. The conclusions derived from animal models showed that CB2 receptors are necessary for modulating food intake and mediating energy balance.

Behavioural biases in the interaction with food objects in virtual reality and its clinical implication for binge eating disorder

Cognitive processes play a central role in the development, maintenance and remission in mental disorders, like in Binge Eating Disorder (BED). Insights into cognitive mechanisms reflected by embodied interaction with food and its connections to clinically relevant psychopathology offer new possibilities for translational diagnostics and interventions. We longitudinally investigated the manual interaction with food in a virtual reality (VR) in 31 patients with BED. Patients were assessed at baseline before participating in a randomized-controlled trial (RCT) investigating a computer-based inhibitory control training programme enhanced by transcranial direct current stimulation (tDCS) and at a 6-week follow-up. At both assessments, an experimental VR paradigm was conducted and patients were characterized concerning eating disorder psychopathology, eating behaviour, general impulsivity and food craving. In the experimental task, one of two simultaneously presented objects (food vs. office tools) had to be collected. Food was recognized faster than office tools and subsequent approach behaviour was initiated faster, whereas thereafter, food was collected slower than office tools. Exploratory, we could not find a modulatory effect of applied tDCS on the interaction with food. No relationship between behavioural biases and sample characterizations could be detected. Two different stages in the manual interaction with food were found: a faster first stage that comprises recognition and movement initiation and a slower second stage that comprises controlled handling and may reflect aversive motivational processes. As the behavioural patterns do not change with an ameliorated BED-psychopathology at the second assessment, the task seems insensitive in detecting translational interconnections between behavioural biases and BED-characteristics.Level of evidence: Level I, experimental study.

Neural correlates of changing food choices while bypassing values

Current theories suggest that altering choices requires value modification. To investigate this, normal-weight female participants' food choices and values were tested before and after an approach-avoidance training (AAT), while neural activity was recorded during the choice task using functional magnetic resonance imaging (fMRI). During AAT, participants consistently approached low- while avoiding high-calorie food cues. AAT facilitated low-calorie food choices, leaving food values unchanged. Instead, we observed a shift in indifference points, indicating the decreased contribution of food values in food choices. Training-induced choice shifts were associated with increased activity in the posterior cingulate cortex (PCC). In contrast, the medial PFC activity was not changed. Additionally, PCC grey matter density predicted individual differences in training-induced functional changes, suggesting anatomic predispositions to training impact. Our findings demonstrate neural mechanisms underlying choice modulation independent of valuation-related processes, with substantial theoretical significance for decision-making frameworks and translational implications for health-related decisions resilient to value shifts.

The nature and persistence of the effects of posthypnotic suggestions on food preferences: The final report of an online study

The persistence of food preferences, which are crucial for diet-related decisions, is a significant obstacle to changing unhealthy eating behavior. To overcome this obstacle, the current study investigates whether posthypnotic suggestions (PHSs) can enhance food-related decisions by measuring food choices and subjective ratings. After assessing hypnotic susceptibility in Session 1, at the beginning of Session 2, a PHS was delivered aiming to increase the desirability of healthy food items (e.g., vegetables and fruit). After the termination of hypnosis, a set of two tasks was administrated twice, once when the PHS was activated and once deactivated in counterbalanced order. The task set consisted of rating 170 pictures of food items, followed by an online supermarket where participants were instructed to select enough food from the same item pool for a fictitious week of quarantine. After 1 week, Session 3 mimicked Session 2 without renewed hypnosis induction to assess the persistence of the PHS effects. The Bayesian hierarchical modeling results indicate that the PHS increased preferences and choices of healthy food items without altering the influence of preferences in choices. In contrast, for unhealthy food items, not only both preferences and choices were decreased due to the PHS, but also their relationship was modified. That is, although choices became negatively biased against unhealthy items, preferences played a more dominant role in unhealthy choices when the PHS was activated. Importantly, all effects persisted over 1 week, qualitatively and quantitatively. Our results indicate that although the PHS affected healthy choices through resolve, i.e., preferred more and chosen more, unhealthy items were probably chosen less impulsively through effortful suppression. Together, besides the translational importance of the current results for helping the obesity epidemic in modern societies, our results contribute theoretically to the understanding of hypnosis and food choices.

The Nature and Persistence of Posthypnotic Suggestions' Effects on Food Preferences: An Online Study

Food preferences are crucial for diet-related decisions, which substantially impact individual health and global climate. However, the persistence of unfavorable food preferences is a significant obstacle to changing eating behavior. Here we explored the effects of posthypnotic suggestions (PHS) on food-related decisions by measuring food choices, subjective ratings, and indifference points. In Session 1, demographic data and hypnotic susceptibility of participants were assessed. In Session 2, following hypnosis induction, PHS aiming to increase the desirability of healthy food was delivered. Afterward, a task set was administrated twice, once when PHS was activated and once deactivated. The order of PHS activation was counterbalanced across participants. The task set included a liking-rating task for 170 pictures of different food items, followed by an online supermarket where participants were instructed to select enough food for a fictitious week of quarantining from the same item pool. After 1 week, Session 3 repeated Session 2 without hypnosis induction in order to assess the persistence of PHS. The crucial dependent measures were food choices, subjective ratings, and the indifference points as a function of time and PHS condition.

Contributing roles of depression, anxiety, and impulsivity dimensions in eating behaviors styles in surgery candidates

BACKGROUND

Even if bariatric surgery is considered the most effective therapeutic approach, it is not equally successful among individuals suffering from severe obesity and candidates for this weight loss surgery. Among the factors that influence postsurgical outcomes, eating behaviors styles are known to play a key role in relapses. The aim of our study was to assess eating behaviors styles and several modulating psychopathological factors in patients suffering from severe obesity.

METHODS

Patients seeking bariatric surgery (N = 127) completed a set of standardized tools assessing eating behaviors (Dutch Eating Behavior Questionnaire), comorbid psychiatric conditions (Mini International Neuropsychiatric Interview), depression, and anxiety scores (Beck Depression Inventory, State-Trait Anxiety Inventory), and impulsivity scores (UPPS-P Impulsive Behavior Scale).

RESULTS

We detected significant correlations between DEBQ Emotional Eating (EmoE) and depression, state and trait anxiety, and all dimensions of impulsivity. Significant correlations were also present between DEBQ External Eating (ExtE) and depression, state and trait anxiety and UPPS-P positive urgency, lack of perseverance and sensation seeking. Regression analyses identified sex (female), trait anxiety, and lack of perseverance as explanatory factors for EmoE, and depression severity score and positive urgency for ExtE.

CONCLUSIONS

EmoE might be a means of dealing with negative emotions and/or intrusive thoughts, while ExtE might result from a mechanism associated with depression. These results should help to improve patients' outcomes by defining specific therapeutic targets in psychological interventions. After bariatric surgery, some patients regain weight. This is likely due to various factors, including a return of maladaptive eating styles, such as emotional eating (which occurs as a response to negative emotions, like depression, anxiety, anger, sadness, and discouragement), external eating (which refers to the tendency to eat in response to positive external cues, regardless of internal signals of hunger and satiety), and restraint eating (implying to make efforts to develop and maintain strategies to control calories intake, associated with weight loss after lifestyle intervention). Our goal in this research project was to explore associated factors (particularly depression, anxiety, and impulsivity) to these eating styles in patients suffering from obesity prior to bariatric surgery. Individuals seeking bariatric surgery were asked questions about their eating styles and their levels of depression, anxiety, and impulsivity using standardized questionnaires. We found that emotional eating might be a means of dealing with negative emotions and/or intrusive thoughts (e.g. about food or body dissatisfaction), while external eating might result from a mechanism associated with depression. We detected no association between restraint eating and any of the dimensions of impulsivity, nor depression and anxiety. Therapies aimed at improving patients' abilities to regulate negative affects seem promising among subjects suffering from obesity and those seeking bariatric surgery. If well learned, these therapies might also help them to maintain weight loss after surgery by limiting maladaptive eating styles.

A review of effort-based decision-making in eating and weight disorders

Effort-based decision-making provides a framework to understand the mental computations estimating the amount of work ("effort") required to obtain a reward. The aim of the current review is to systematically synthesize the available literature on effort-based decision-making across the spectrum of eating and weight disorders. More specifically, the current review summarises the literature examining whether 1) individuals with eating disorders and overweight/obesity are willing to expend more effort for rewards compared to healthy controls, 2) if particular components of effort-based decision-making (i.e. risk, discounting) relate to specific binge eating conditions, and 3) how individual differences in effort and reward -processing measures relate to eating pathology and treatment measures. A total of 96 studies were included in our review, following PRISMA guidelines. The review suggests that individuals with binge eating behaviours 1) are more likely to expend greater effort for food rewards, but not monetary rewards, 2) demonstrate greater decision-making impairments under risk and uncertainty, 3) prefer sooner rather than delayed rewards for both food and money, and 4) demonstrate increased implicit 'wanting' for high fat sweet foods. Finally, individual differences in effort and reward -processing measures relating to eating pathology and treatment measures are also discussed.

Temporal discounting as a candidate behavioral marker of obesity

Although obesity is a result of processes operating at multiple levels, most forms result from decision-making behavior. The aim of this review was to examine the candidacy of temporal discounting (TD) (i.e. the reduction in the value of a reinforcer as a function of the delay to its receipt) as a behavioral marker of obesity. For this purpose, we assessed whether TD has the ability to: identify risk for obesity development, diagnose obesity, track obesity progression, predict treatment prognosis/outcomes, and measure treatment effectiveness. Three databases (Pubmed, PsycINFO, and Web of Science) were searched using a combination of terms related to TD and obesity. A total of 153 papers were reviewed. Several areas show strong evidence of TD's predictive utility as a behavioral marker of obesity (e.g., distinguishing obese from non obese). However, other areas have limited and/or mixed evidence (e.g., predicting weight change). Given the positive relationship for TD in the majority of domains examined, further consideration for TD as a behavioral marker of obesity is warranted.

Food reinforcement and habituation to food are processes related to initiation and cessation of eating

An individual bout of eating involves cues to start eating, as well as cues to terminate eating. One process that determines initiation of eating is food reinforcement. Foods with high reinforcing value are also likely to be consumed in greater quantities. Research suggests both cross-sectional and prospective relationships between food reinforcement and obesity, food reinforcement is positively related to energy intake, and energy intake mediates the relationship between food reinforcement and obesity. A process related to cessation of eating is habituation. Habituation is a general behavioral process that describes a reduction in physiological or affective response to a stimulus, or a reduction in the behavioral responding to obtain a stimulus. Repeated exposure to the same food during a meal can result in habituation to that food and a reduction in consumption. Habituation is also cross-sectionally and prospectively related to body weight, as people who habituate slower consume more in a meal and are more overweight. Research from our laboratory has shown that these two processes independently influence eating, as they can account for almost 60% of the variance in ad libitum intake. In addition, habituation phenotypes show reliable relationships with reinforcing value, such that people who habituate faster also find food less reinforcing. Developing a better understanding of cues to start and stop eating is fundamental to understanding how to modify eating behavior. An overview of research on food reinforcement, habituation and food intake for people with a range of weight status and without eating disorders is provided, and ideas about integrating these two processes that are related to initiation and termination of a bout of eating are discussed.

Gender difference in determinant factors of being overweight among the 40-70-year-old population of Kharameh cohort study, Iran

Background

Iranians face being overweight as one of the most common health problems, which is more prevalent among women. This study aimed to identify gender differences in determinants of being overweight in 40- to 70-year-old participants from Kharameh, Iran.

Methods

This cross-sectional study was conducted during 2015–2016. The total 10,663 inhabitants of Kharameh, Iran, aged 40–70 years old, were target population. Those with a body mass index (BMI) < 18.5 or > 29.9 were excluded. A checklist composed of socio-demographic, lifestyle, and BMI items was used; a p-value < 0.05 was considered significant.

Results

Overall, 53.4% of 8222 participants were overweight. The prevalence of overweight women (62.7%) was significantly higher (p <  0.001) than men (43.6%).

The logistic regression model for men showed that being overweight was more likely among men with cigarette smoking history (OR = 1.49) and those with a moderate physical activity level (OR = 1.35), but less likely among those with a higher socio-economic status (SES) (OR = 0.74). Among women, being overweight was associated with high SES (OR = 1.61), an education level below high school diploma (OR = 1.57) and primary school education (OR = 1.50), being married (OR = 2.39), widowed (OR = 2.11) and having a greater calorie intake (OR = 1.01). Being overweight was less likely among employed women (OR = 0.85), those with cigarette smoking history (OR = 0.65), and those with high (OR = 0.72) and intensive physical activity (OR = 0.73).

Conclusions

This study revealed the gender differences in determining factors affecting being overweight. As being overweight was more prevalent among women, the priority of health policies to control this issue should also be focused on women.

Changes in visual attention towards food cues after obesity surgery: An eye-tracking study

Research documented the effectiveness of obesity surgery (OS) for long-term weight loss and improvements in medical and psychosocial sequelae, and general cognitive functioning. However, there is only preliminary evidence for changes in attentional processing of food cues after OS. This study longitudinally investigated visual attention towards food cues from pre- to 1-year post-surgery. Using eye tracking (ET) and a Visual Search Task (VST), attentional processing of food versus non-food cues was assessed in n = 32 patients with OS and n = 31 matched controls without weight-loss treatment at baseline and 1-year follow-up. Associations with experimentally assessed impulsivity and eating disorder psychopathology and the predictive value of changes in visual attention towards food cues for weight loss and eating behaviors were determined. During ET, both groups showed significant gaze duration biases to non-food cues without differences and changes over time. No attentional biases over group and time were found by the VST. Correlations between attentional data and clinical variables were sparse and not robust over time. Changes in visual attention did not predict weight loss and eating disorder psychopathology after OS. The present study provides support for a top-down regulation of visual attention to non-food cues in individuals with severe obesity. No changes in attentional processing of food cues were detected 1-year post-surgery. Further studies are needed with comparable methodology and longer follow-ups to clarify the role of biased visual attention towards food cues for long-term weight outcomes and eating behaviors after OS.

Fetal Programming by Methyl Donors Modulates Central Inflammation and Prevents Food Addiction-Like Behavior in Rats

Fetal programming by hypercaloric intake leads to food addiction-like behavior and brain pro-inflammatory gene expression in offspring. The role of methylome modulation during programming on central immune activation and addiction-like behavior has not been characterized. We employed a nutritional programming model exposing female Wistar rats to chow diet, cafeteria (CAF), or CAF-methyl donor’s diet from pre-pregnancy to weaning. Addiction-like behavior in offspring was characterized by the operant training response using Skinner boxes. Food intake in offspring was determined after fasting–refeeding schedule and subcutaneous injection of ghrelin. Genome-wide DNA methylation in the nucleus accumbens (NAc) shell was performed by fluorescence polarization, and brain immune activation was evaluated using real-time PCR for pro-inflammatory cytokines (IL-1β, TNF-1α, and IL-6). Molecular effects of methyl modulators [S-adenosylmethionine (SAM) or 5-azatidine (5-AZA)] on pro-inflammatory cytokine expression and phagocytosis were identified in the cultures of immortalized SIM-A9 microglia cells following palmitic acid (100 μM) or LPS (100 nM) stimulation for 6 or 24 h. Our results show that fetal programming by CAF exposure increases the number of offspring subjects and reinforcers under the operant training response schedule, which correlates with an increase in the NAc shell global methylation. Notably, methyl donor’s diet selectively decreases lever-pressing responses for reinforcers and unexpectedly decreases the NAc shell global methylation. Also, programmed offspring by CAF diet shows a selective IL-6 gene expression in the NAc shell, which is reverted to control values by methyl diet exposure. In vitro analysis identified that LPS and palmitic acid activate IL-1β, TNF-1α, and IL-6 gene expression, which is repressed by the methyl donor SAM. Finally, methylation actively represses phagocytosis activity of SIM-A9 microglia cells induced by LPS and palmitic acid stimulation. Our in vivo and in vitro data suggest that fetal programming by methyl donors actively decreases addiction-like behavior to palatable food in the offspring, which correlates with a decrease in NAc shell methylome, expression of pro-inflammatory cytokine genes, and activity of phagocytic microglia. These results support the role of fetal programming in brain methylome on immune activation and food addiction-like behavior in the offspring.

Laboratory-based interventions targeting food craving: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to quantify the effects of laboratory-based interventions targeting specific mechanisms of food craving, to identify moderators of effects, and to qualitatively summarize findings. The study was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Sixty-nine studies were included in the quantitative synthesis, and separate meta-analyses were conducted for the outcomes self-reported craving and objective food intake. Results show small to medium positive effects across specific craving interventions on both outcomes. Effect sizes were partly moderated by intervention type. The most effective intervention regarding food intake was in sensu cue exposure. For subjective craving, the most robust evidence was found for beneficial effects of cognitive regulation strategies (ie, reappraisal, suppression, and distraction). Results further indicate that training inhibitory control through behavioral inhibition might be more effective than approach-avoidance training when considering its effect on subjective craving and food intake. People with external eating habits, overeating, or loss-of-control eating might benefit from these types of specific craving interventions. Future research should focus on long-term effects, transferability, and effectiveness in clinical samples.

Attentional bias for alcohol cues in visual search-Increased engagement, difficulty to disengage or both?

Cognitive models emphasise the importance of attentional bias in addiction. However, many attentional bias tasks have been criticised for questionable psychometric properties and inability to differentiate between engagement and disengagement processes. This study therefore examined the suitability of two alternative tasks for assessing attentional bias within the context of alcohol use. Participants were undergraduate students (N = 169) who completed the Visual Search Task and Odd-One-Out Task, the latter of which is designed to differentiate between engagement and disengagement processes of attention, at baseline and one week later. Participants also completed baseline measures of alcohol consumption, craving, and alcohol use problems. Internal consistency was adequate for the Visual Search Task index, and weak for the Odd-One-Out Task indices. Test-retest reliability was weak for both tasks. The Visual Search Task index and the disengagement (but not the engagement) index of the Odd-One-Out Task showed a positive association with alcohol consumption. This study was restricted to a non-clinical student sample. The relatively high error rate of the Odd-One-Out Task might have reduced its sensitivity as an index of attentional bias. Both tasks showed some merit as attentional bias measures, and results suggested that attentional disengagement might be particularly related to alcohol use. However, the reliability of the current measures was inadequate. One potential explanation for the low reliability is that non-clinical samples may have weak and unstable attentional biases to alcohol. Future efforts should be made to improve the psychometric qualities of both tasks and to administer them in a clinical sample.

ERP correlates of cognitive control and food-related processing in normal weight and severely obese candidates for bariatric surgery: Data gathered using a newly designed Simon task

Although there have been suggestions that altered cognitive control and food reward sensitivity contribute to overeating in obese individuals, neurophysiological correlates of these mechanisms have been poorly investigated. The current study investigated event-related potentials (ERP) in 24 severely obese and 26 normal weight individuals in fasting condition, using a novel Simon task with food and object distractors. The study showed that conflict in the Simon task for the food distractor increased with hunger in both groups but was larger with respect to a neutral condition only in the obese individuals. ERP showed higher N1amplitudes in both groups for food distractor, reflecting early food processing. The P2 latency was delayed and the effect of distractors on N2 amplitude was smaller in the obese subjects, reflecting altered neural mechanisms associated with selective attention and cognitive control, all contributing hypothetically to delay response selection of these individuals faced with food distractor.

The Executive Functions in Overweight and Obesity: A Systematic Review of Neuropsychological Cross-Sectional and Longitudinal Studies

Background: The increasing incidence of people affected by overweight or obesity is a significant health problem. The knowledge of the factors which influences the inappropriate eating behaviors causing excessive body fat is an essential goal for the research. Overweight and obesity are significant risk factors for many health diseases, such as cardiovascular problems, diabetes. Recently, many studies have focused on the relationship between body weight and cognitive processes. Objectives: This systematic review is aimed to investigate the existence and the nature of the relationship between excessive body weight (overweight/obesity) and executive functions, analyzing cross-sectional, and longitudinal studies in order to verify the evidence of a possible causality between these variables. Methods: The review was carried out according to the PRISMA-Statement, through systematic searches in the scientific databases PubMed, Medline, PsychInfo, and PsycArticles. The studies selected examined performance on executive tasks by participants with overweight or obesity, aged between 5 and 70 years. Studies examining eating disorders or obesity resulting from other medical problems were excluded. Furthermore, the results of studies using a cross-sectional design and those using a longitudinal one were separately investigated. Results: Sixty-three cross-sectional studies and twenty-eight longitudinal studies that met our inclusion and exclusion criteria were analyzed. The results confirmed the presence of a relation between executive functions and overweight/obesity, although the directionality of this relation was not clear; nor did any single executive function emerge as being more involved than others in this relation. Despite this, there was evidence of a reciprocal influence between executive functions and overweight/obesity. Conclusions: This systematic review underlines the presence of a relationship between executive functions and overweight/obesity. Moreover, it seems to suggest a bidirectional trend in this relationship that could be the cause of the failure of interventions for weight reduction. The results of this review highlight the importance of a theoretical model able to consider all the main variables of interest, with the aim to structuring integrated approaches to solve the overweight/obesity problems.

Overweight adults are more impulsive than normal weight adults: Evidence from ERPs during a chocolate-related delayed discounting task

Overweight or obesity can be accompanied by abnormalities in executive function and related neural markers. The aim of the present study was to investigate the behavioral and neural correlates of food-related decision-making in overweight and normal-weight adults. We used a delayed discounting task (DDT), which requires participants to choose between smaller immediate rewards and larger delayed rewards. In total, 24 overweight adults and 24 normal-weight adults participated; all participants engaged with a food-related DDT, and their responses were measured using event-related potentials (ERPs). In the current study, we take the area under the curve (AUC), number of smaller immediate rewards, and reaction times (RTs) as behavioral indicators of DDT. AUC is an individual's discounting rate, with smaller AUC reflecting more impulsive decision-making. Number of smaller immediate rewards also reflects impulsivity. For ERPs, N2, reward-related positivity, P3, and late positive component (LPC) were investigated. Behavioral results showed smaller AUC, more choice of smaller immediate rewards, and longer RTs in overweight adults than in normal-weight adults. Neural markers showed that overweight adults elicited greater N2 in larger delayed rewards than in smaller immediate rewards and also elicited greater reward-related positivity than normal-weight adults. Moreover, the P3 and LPC mean amplitudes of overweight adults were greater than those of normal-weight adults. Pearson correlation analysis showed that body mass index (BMI) was positively related to P3 and LPC, while AUC was negatively related to P3. The findings thus suggest that overweight adults are more impulsive than normal-weight adults. Moreover, overweight adults might experience more cognitive conflict before their reaction, and they might allocate more cognitive resources to food-related stimuli and might have higher-order cognitive processes more involved in motivation or emotion regarding food-related stimuli. This is the first study investigating ERP correlates of food-related decision-making in overweight adults, and it enriches the theoretical models by providing neural markers for future study.

A new approach to facilitating attentional disengagement from food cues in unsuccessful dieters: The bouncing image training task

This study tested the capacity of a modified Bouncing Image Training Task (BITT) to enhance unsuccessful dieters' attentional disengagement from food cues. Unsuccessful dieters were assigned to a training group performing daily BITT sessions for one week (n = 57) or a waitlist control group (n = 56). Change in attention was assessed using a visual search task and an odd-one-out task. Impact of the BITT on food craving and food intake were also assessed. Participants in the training group, compared to waitlist controls, showed reduced attention to food cues from pre-to post-training. Moreover, the reduction in AB to food cues exhibited by those who completed the BITT reflected the relative facilitation of attentional disengagement from food cues, rather than a reduction in attention engagement with food cues. The groups did not differ on food craving or intake post-training. It is concluded that the BITT is a promising procedure for directly manipulating individuals' attentional disengagement from food cues, though its capacity to enhance dieting success has not yet been established.

Sweet cognition: The differential effects of glucose consumption on attentional food bias in individuals of lean and obese status

In general, glucose consumption improves cognitive performance; however, it is unknown whether glucose specifically alters attentional food bias, and how this process may vary by BMI status. We hypothesized that glucose consumption would increase attentional food bias among individuals of obese BMI status more so than among individuals of lean BMI status. Participants (N = 35) completed the n-back, a working memory task modified to assess attentional food bias (ATT-Food), under fasting and glucose challenge conditions. We computed pre-post changes in ATT-Food, blood glucose and insulin (∆BG & ∆BI), and perceived task-stress (∆stress). After the second cognitive test and blood draw, participants ate lunch and completed a "taste test" of highly palatable foods, and we recorded food consumption. Pre-post changes in ATT-Food were greater among participants of obese (relative to lean) BMI status (F(1,33) = 5.108, p = .031). Greater ∆ATT-Food was significantly associated with greater ∆BG (r = .462, p = .007) and reduced ∆stress (r =-.422, p = .011), and marginally associated with greater taste-test eating (r =.325, p = .057), but was not associated with ∆BI. Our findings suggest that individuals of obese BMI status may exhibit "sweet cognition," as indexed by greater attentional food bias following glucose ingestion, relative to individuals of lean BMI status. Among individuals of obese BMI status, sweet cognition may arise from difficulty broadening attention toward non-food cues after consuming a high glucose load, thereby potentially perpetuating sugar consumption. If confirmed by further research, measures of sweet cognition may help identify individuals with a phenotype of risk for obesity and greater sugar consumption, who may benefit from tailored interventions.

Role of oxytocin in the control of stress and food intake

Oxytocin neurones in the hypothalamus are activated by stressful stimuli and food intake. The oxytocin receptor is located in various brain regions, including the sensory information-processing cerebral cortex; the cognitive information-processing prefrontal cortex; reward-related regions such as the ventral tegmental areas, nucleus accumbens and raphe nucleus; stress-related areas such as the amygdala, hippocampus, ventrolateral part of the ventromedial hypothalamus and ventrolateral periaqueductal gray; homeostasis-controlling hypothalamus; and the dorsal motor complex controlling intestinal functions. Oxytocin affects behavioural and neuroendocrine stress responses and terminates food intake by acting on the metabolic or nutritional homeostasis system, modulating emotional processing, reducing reward values of food intake, and facilitating sensory and cognitive processing via multiple brain regions. Oxytocin also plays a role in interactive actions between stress and food intake and contributes to adaptive active coping behaviours.

The Cognitive Drivers of Compulsive Eating Behavior

Compulsivity is a central feature of obsessive-compulsive and addictive disorders, which share considerable overlap with excessive eating in terms of repetitive behavior despite negative consequences. Excessive eating behavior is characteristic of several eating-related conditions, including eating disorders [bulimia nervosa (BN), binge eating disorder (BED)], obesity, and food addiction (FA). Compulsivity is proposed to be driven by four distinct cognitive components, namely, contingency-related cognitive flexibility, task/attentional set-shifting, attentional bias/disengagement and habit learning. However, it is unclear whether repetitive behavior in eating-related conditions is underpinned by deficits in these cognitive components. The current mini-review synthesizes the available evidence for performance on compulsivity-related cognitive tasks for each cognitive domain among populations with excessive eating behavior. In three of the four cognitive domains, i.e., set-shifting, attentional bias and habit learning, findings were mixed. Evidence more strongly pointed towards impaired contingency-related cognitive flexibility only in obesity and attentional bias/disengagement deficits only in obesity and BED. Overall, the findings of the reviewed studies support the idea that compulsivity-related cognitive deficits are common across a spectrum of eating-related conditions, although evidence was inconsistent or lacking for some disorders. We discuss the theoretical and practical importance of these results, and their implications for our understanding of compulsivity in eating-related conditions.

A second type of magnitude effect: Reinforcer magnitude differentiates delay discounting between substance users and controls

Basic research on delay discounting, examining preference for smaller-sooner or larger-later reinforcers, has demonstrated a variety of findings of considerable generality. One of these, the magnitude effect, is the observation that individuals tend to exhibit greater preference for the immediate with smaller magnitude reinforcers. Delay discounting has also proved to be a useful marker of addiction, as demonstrated by the highly replicated finding of greater discounting rates in substance users compared to controls. However, some research on delay discounting rates in substance users, particularly research examining discounting of small-magnitude reinforcers, has not found significant differences compared to controls. Here, we hypothesize that the magnitude effect could produce ceiling effects at small magnitudes, thus obscuring differences in delay discounting between groups. We examined differences in discounting between high-risk substance users and controls over a broad range of magnitudes of monetary amounts ($0.10, $1.00, $10.00, $100.00, and $1000.00) in 116 Amazon Mechanical Turk workers. We found no significant differences in discounting rates between users and controls at the smallest reinforcer magnitudes ($0.10 and $1.00) and further found that differences became more pronounced as magnitudes increased. These results provide an understanding of a second form of the magnitude effect: That is, differences in discounting between populations can become more evident as a function of reinforcer magnitude.

Impulsivity and vitamin D in bariatric surgery candidates

BACKGROUND

Obesity is recognized as a major health problem. Vitamin D is involved in maintaining energy metabolism by regulation of glucose transporters, uncoupling proteins, and normal brain function. We aimed to explore a relationship between impulsivity, eating behaviors, and 25-hydroxyvitamin D concentration in a sample of 322 bariatric surgery candidates.

METHODS

Participants completed a questionnaire on their health, eating habits and The Eating Disorders Examination-Questionnaire (EDE-Q). Impulsivity was evaluated with the Barratt Impulsiveness Scale (BIS-11). Blood samples were obtained to measure levels of 25(OH)D, lipids (cholesterol, triglyceride, HDL-cholesterol, LDL-cholesterol), and glucose.

RESULTS

Overall scores on the BIS-11, along with scores on the Attentional Subscale of the BIS were significantly higher in participants with higher frequency of snack food consumption. Scores on the Attentional Subscale of the BIS were higher in participants who self-reported eating in response to emotions. Participants who reported eating at night or declared intense emotions associated with a desire-to-eat had the highest global, attentional, and non-planning impulsivity levels. Scores on the Non-planning Subscale of the BIS-11 were elevated in participants with 25-hydroxyvitamin D concentrations lower than 10ng/ml.

CONCLUSIONS

The results suggest that the higher level of impulsivity among the patients with obesity is associated with eating habits, and support the hypothesis that vitamin D deficiency may contribute to impulsiveness.

Food-Related Impulsivity in Obesity and Binge Eating Disorder-A Systematic Update of the Evidence

The specific eating pattern of Binge Eating Disorder (BED) patients has provoked the assumption that BED might represent a phenotype within the obesity spectrum that is characterized by increased impulsivity. Following the guidelines of the PRISMA statement (preferred reporting items for systematic reviews and meta-analyses), we here provide a systematic update on the evidence on food-related impulsivity in obese individuals, with and without BED, as well as normal-weight individuals. We separately analyzed potential group differences in the impulsivity components of reward sensitivity and rash-spontaneous behavior. Our search resulted in twenty experimental studies with high methodological quality. The synthesis of the latest evidence consolidates conclusions drawn in our initial systematic review that BED represents a distinct phenotype within the obesity spectrum that is characterized by increased impulsivity. Rash-spontaneous behavior in general, and specifically towards food, is increased in BED, while food-specific reward sensitivity is also increased in obese individuals without BED, but potentially to a lesser degree. A major next step for research entails the investigation of sub-domains and temporal components of inhibitory control in BED and obesity. Based on the evidence of impaired inhibitory control in BED, affected patients might profit from interventions that address impulsive behavior.

The association between in vivo central noradrenaline transporter availability and trait impulsivity

The brain noradrenaline (NA) system, particularly NA transporters (NAT), are thought to play an important role in modulating impulsive behavior. Impaired impulsivity is implicated in a variety of neuropsychiatric conditions; however, an in vivo link between central NAT availability and human impulsivity has not been shown. Using positron emission tomography (PET) and S,S-[¹¹C]O-methylreboxetine (MRB), we tested whether NAT availability is associated with this basic behavioral trait based on the Barratt Impulsiveness Scale (BIS-11) in twenty healthy individuals (12 females, 33.8±9.3, 21-52 years of age) with a body mass index (BMI) ranging from 21.7kg/m² to 47.8kg/m². Applying both voxel-wise and volume-of-interest (VOI) based analyses, we found that distribution volume ratios (DVR) used as PET outcome measures negatively correlated with BIS-11 total scores in the orbitofrontal cortex (OFC) and in the hippocampus as well as in parts of the cerebellar cortex. These associations however did not remain after correction for multiple testing. Thus, although it appears that low NAT availability is associated with greater scores of impaired behavioral control, this needs to be confirmed in a larger series of individuals with highly impulsive behavior.

Maximizing potential impact of experimental research into cognitive processes in health psychology: A systematic approach to material development

BACKGROUND

There is an abundance of research into cognitive processing biases in clinical psychology including the potential for applying cognitive bias modification techniques to assess the causal role of biases in maintaining anxiety and depression. Within the health psychology field, there is burgeoning interest in applying these experimental methods to assess potential cognitive biases in relation to physical health conditions and health-related behaviours. Experimental research in these areas could inform theoretical development by enabling measurement of implicit cognitive processes that may underlie unhelpful illness beliefs and help drive health-related behaviours. However, to date, there has been no systematic approach to adapting existing experimental paradigms for use within physical health research. Many studies fail to report how materials were developed for the population of interest or have used untested materials developed ad hoc. The lack of protocol for developing stimuli specificity has contributed to large heterogeneity in methodologies and findings.

PURPOSE

In this article, we emphasize the need for standardized methods for stimuli development and replication in experimental work, particularly as it extends beyond its original anxiety and depression scope to other physical conditions.

METHOD

We briefly describe the paradigms commonly used to assess cognitive biases in attention and interpretation and then describe the steps involved in comprehensive/robust stimuli development for attention and interpretation paradigms using illustrative examples from two conditions: chronic fatigue syndrome and breast cancer.

CONCLUSIONS

This article highlights the value of preforming rigorous stimuli development and provides tools to aid researchers engage in this process. We believe this work is worthwhile to establish a body of high-quality and replicable experimental research within the health psychology literature. Statement of contribution What is already known on this subject? Cognitive biases (e.g., tendencies to attend to negative information and/or interpret ambiguous information in negative ways) have a causal role in maintaining anxiety and depression. There is mixed evidence of cognitive biases in physical health conditions and chronic illness; one reason for this may be the heterogeneous stimuli used to assess attention and interpretation biases in these conditions. What does this study add? Steps for comprehensive/robust stimuli development for attention and interpretation paradigms are presented. Illustrative examples are provided from two conditions: chronic fatigue syndrome and breast cancer. We provide tools to help researchers develop condition-specific materials for experimental studies.

The Effect of Implicit Preferences on Food Consumption: Moderating Role of Ego Depletion and Impulsivity

Ego depletion has been found to moderate the effect of implicit preferences on food consumption, such that implicit preferences predict consumption only under a depleted state. The present study tested how trait impulsivity impacts the effect of implicit preferences on food consumption in a depleted condition. Trait impulsivity was measured by means of self-report and a stop signal task. Results showed that both self-reported impulsivity and behavioral impulsivity moderated the 'depletion and then eating according to implicit preferences' effect, albeit in different ways. Participants high in self-reported impulsivity and low in behavioral impulsivity were more vulnerable to the effect of depletion on eating. The implications of these results for extant theories are discussed. Future research is needed to verify whether or not trait impulsivity is associated with vulnerability to depletion across different self-control domains.

Neuronal systems and circuits involved in the control of food intake and adaptive thermogenesis

With the still-growing prevalence of obesity worldwide, major efforts are made to understand the various behavioral, environmental, and genetic factors that promote excess fat gain. Obesity results from an imbalance between energy intake and energy expenditure, which emphasizes the importance of deciphering the mechanisms behind energy balance regulation to understand its physiopathology. The control of energy balance is assured by brain systems/circuits capable of generating adequate ingestive and thermogenic responses to maintain the stability of energy reserves, which implies a proper integration of the homeostatic signals that inform about the status of the energy stores. In this article, we overview the organization and functionality of key neuronal circuits or pathways involved in the control of food intake and energy expenditure. We review the role of the corticolimbic (executive and reward) and autonomic systems that integrate their activities to regulate energy balance. We also describe the mechanisms and pathways whereby homeostatic sensing is achieved in response to variations of homeostatic hormones, such as leptin, insulin, and ghrelin, while putting some emphasis on the prominent importance of the mechanistic target of the rapamycin signaling pathway in coordinating the homeostatic sensing process.

Reduced Inhibitory Control Mediates the Relationship Between Cortical Thickness in the Right Superior Frontal Gyrus and Body Mass Index

Unhealthy eating behaviors often develop in the setting of inadequate inhibitory control, a function broadly ascribed to the prefrontal cortex (PFC). Regulation of inhibitory control by the PFC and its anatomical components and their contribution to increasing body mass index (BMI) are poorly understood. To study the role of PFC in the regulation of inhibitory control and body weight, we examined measures of cortical thickness in PFC sub-regions, inhibitory control (color-word interference task (CWIT)), and BMI in 91 healthy volunteers. We tested the predictive effect of PFC sub-regional cortical thickness on BMI and mediation by inhibitory control measured with CWIT. Measures of depression (BDI-II), anxiety (STAI-T) and trauma-related symptoms (TSC-40) were collected; the disinhibition scale of the three-factor eating questionnaire (TFEQ) was used to assess disinhibited eating. We then tested the relationship between BD-II, STAI-T, TSC-40, TFEQ, CWIT, and BMI with correlation analyses. Right superior frontal gyrus cortical thickness significantly predicted BMI (β=-0.91; t=-3.2; p=0.002). Mediation analysis showed a significant indirect effect of cortical thickness on BMI mediated by inhibitory control (95% CI=-6.1, -0.67). BMI was unrelated to BDI-II, STAI-T, TSC-40, or TFEQ scores. We found an inverse relationship between cortical thickness in the right-superior frontal gyrus and BMI, which was fully mediated by inhibitory control neurocognitive performance. Our results suggest possible targets for neuromodulation in obesity (ie superior frontal gyrus) and a quantifiable mediator of their effects (ie inhibitory control).

Steep discounting of delayed monetary and food rewards in obesity: a meta-analysis

BACKGROUND

An increasing number of studies have investigated delay discounting (DD) in relation to obesity, but with mixed findings. This meta-analysis synthesized the literature on the relationship between monetary and food DD and obesity, with three objectives: (1) to characterize the relationship between DD and obesity in both case-control comparisons and continuous designs; (2) to examine potential moderators, including case-control v. continuous design, money v. food rewards, sample sex distribution, and sample age (18 years); and (3) to evaluate publication bias.

METHOD

From 134 candidate articles, 39 independent investigations yielded 29 case-control and 30 continuous comparisons (total n = 10 278). Random-effects meta-analysis was conducted using Cohen's d as the effect size. Publication bias was evaluated using fail-safe N, Begg-Mazumdar and Egger tests, meta-regression of publication year and effect size, and imputation of missing studies.

RESULTS

The primary analysis revealed a medium effect size across studies that was highly statistically significant (d = 0.43, p < 10-14). None of the moderators examined yielded statistically significant differences, although notably larger effect sizes were found for studies with case-control designs, food rewards and child/adolescent samples. Limited evidence of publication bias was present, although the Begg-Mazumdar test and meta-regression suggested a slightly diminishing effect size over time.

CONCLUSIONS

Steep DD of food and money appears to be a robust feature of obesity that is relatively consistent across the DD assessment methodologies and study designs examined. These findings are discussed in the context of research on DD in drug addiction, the neural bases of DD in obesity, and potential clinical applications.

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.

Splitting, impulsivity, and intimate partnerships in young obese women seeking bariatric treatment

BACKGROUND

Splitting represents a defense mechanism that describes fragmentation of conscious experience that may occur in various psychopathological conditions. The purpose of this study was to examine the relationship of splitting with disturbed cognitive and affective functions related to impulsivity and intimate partnerships in a group of obese patients indicated for bariatric treatment and compare the results with other obese patients and patients with bulimia nervosa.

METHODS

In this clinical study, we assessed 102 young women. The sample was divided into three subgroups: obese women (N=30), obese women indicated for bariatric treatment (N=48), and patients with bulimia nervosa (N=24). The patients were assessed using Splitting Index and Barratt Impulsivity Scale, and selected information about their intimate partnership was documented for all the participants.

RESULTS

The main results of this study indicate significant differences in the relationship of splitting and impulsivity with difficulties in intimate partnerships. These differences discriminate obese patients indicated for bariatric treatment from other obese patients and patients with bulimia nervosa.

CONCLUSION

These findings may have significant implications for treatment of the obese patients indicated for bariatric treatment and their presurgery psychological evaluations.

Cognitive and autonomic determinants of energy homeostasis in obesity

Obesity ensues from an imbalance between energy intake and expenditure that results from gene-environment interactions, which favour a positive energy balance. A society that promotes unhealthy food and encourages sedentary lifestyle (that is, an obesogenic environment) has become a major contributory factor in excess fat deposition in individuals predisposed to obesity. Energy homeostasis relies upon control of energy intake as well as expenditure, which is in part determined by the themogenesis of brown adipose tissue and mediated by the sympathetic nervous system. Several areas of the brain that constitute cognitive and autonomic brain systems, which in turn form networks involved in the control of appetite and thermogenesis, also contribute to energy homeostasis. These networks include the dopamine mesolimbic circuit, as well as the opioid, endocannabinoid and melanocortin systems. The activity of these networks is modulated by peripheral factors such as hormones derived from adipose tissue and the gut, which access the brain via the circulation and neuronal signalling pathways to inform the central nervous system about energy balance and nutritional status. In this Review, I focus on the determinants of energy homeostasis that have emerged as prominent factors relevant to obesity.

In psychiatrically healthy individuals, overweight women but not men have lower tryptophan levels

Gender differences in tryptophan (TRP) breakdown in obese individuals have been previously reported. This could be both contributory to, as well as a consequence of, gender differences in mood changes among obese people. To exclude the potential effect of depression on TRP breakdown and its levels in obesity, we replicated analyses in psychiatrically healthy individuals. In 1000 participants, plasma kynurenine (KYN), TRP, and the KYN/TRP ratio were compared between overweight/obese and normal-weight individuals using analysis of covariance, with adjustment for age and gender. Bivariate post hoc tests were also conducted. There were no significant relationships between KYN, TRP, or the KYN/TRP ratio and overall overweight/obese status. However, a significant gender by weight category interaction was identified for TRP only, with overweight/obese women having lower TRP than overweight/obese men (p = 0.02). No gender differences in TRP were found in non-obese participants. Our study in psychiatrically healthy individuals suggested that lower TRP levels in obese women were not secondary to depression, strengthening the possibility that TRP levels could mediate depression in vulnerable women. Thus experimental manipulations of TRP levels could be used to advance theoretical knowledge, prevention, and clinical control of depression in obese women.