GABA (gamma-aminobutyric acid) levels in dorsal anterior cingulate cortex are negatively associated with food motivation in a pediatric sample.

Food motivation varies between individuals, affecting body weight and risk for eating disorders. Prior neuroimaging studies in youth and adults have revealed functional and structural alterations in the anterior cingulate cortex [ACC] in those with obesity and disordered eating but have not investigated their neurochemical underpinnings. In a sample of 37 children aged 4 to 13 years old, we used Magnetic Resonance Spectroscopy [MRS] to assess levels of γ-aminobutyric acid [GABA] - the major inhibitory neurotransmitter in the human brain - quantified relative to creatine in a 27-ml voxel including the dorsal ACC. We used the CEBQ to assess trait food motivation. In analyses adjusting for age, lower GABA+/Cr levels in the dorsal ACC were associated with higher trait enjoyment of food. Higher enjoyment of food scores were in turn associated with higher energy intake during an ad libitum test meal and during a postprandial task assessing intake in the absence of hunger, and higher body weight. Our results indicate a role for GABA function in the dorsal ACC in determining individual variation in food motivation in children.

Shared and distinct alterations in brain morphology in children with ADHD and obesity: Reduced cortical surface area in ADHD and thickness in overweight/obesity.

OBJECTIVE: To investigate shared versus distinct differences in brain structure among children with ADHD and obesity, we examined the morphology of regions implicated in cognitive control and reward function in a single cross-sectional cohort of children with and without ADHD and overweight/obesity (OV/OB). METHOD: Participants included 471 children ages 8-12 years with ADHD (n = 244; 58 OV/OB) and neurotypical (NT) controls (n = 227; 81 OV/OB) classified as healthy-weight (HW; BMI %ile 5th to <85th) vs. having OV/OB (BMI %ile≥85th). Structural MRI was performed to obtain measures of cortical and subcortical morphology and compared across ADHD × BMI groups. RESULTS: Surface area was generally lower in ADHD vs. NT including in anterior cingulate cortex (ACC), dorsolateral prefrontal cortex (dlPFC), medial (m)PFC, and primary motor (M1) cortex. In contrast, cortical thickness was generally lower in OV/OB vs. HW for ACC, dlPFC, orbitofrontal cortex (OFC), mPFC, and supplementary motor cortex (SMC). Furthermore, ADHD × OV/OB interactions were observed for the ACC and OFC, with the lowest ACC volume in the ADHD + OV/OB group and the highest OFC surface area in the NT + OV/OB group. Subcortical volumes did not differ between groups. CONCLUSIONS: Our findings reveal distinct alterations in cortical morphology in association with ADHD and overweight, with cortical surface area reduced in ADHD vs. thickness reduced in OV/OB. Additionally, the findings provide evidence of combined effects of ADHD × OV/OB in brain regions integral to cognition and motivation. Our results support further investigation of causes and correlates of shared and distinct ADHD- and OV/OB-associated differences in developing frontocingulate morphology.

Neighborhood Food Access in Early Life and Trajectories of Child Body Mass Index and Obesity.

Importance: Limited access to healthy foods, resulting from residence in neighborhoods with low food access, is a public health concern. The contribution of this exposure in early life to child obesity remains uncertain. Objective: To examine associations of neighborhood food access during pregnancy or early childhood with child body mass index (BMI) and obesity risk. Design, Setting, and Participants: Data from cohorts participating in the US nationwide Environmental Influences on Child Health Outcomes consortium between January 1, 1994, and March 31, 2023, were used. Participant inclusion required a geocoded residential address in pregnancy (mean 32.4 gestational weeks) or early childhood (mean 4.3 years) and information on child BMI. Exposures: Residence in low-income, low-food access neighborhoods, defined as low-income neighborhoods where the nearest supermarket is more than 0.5 miles for urban areas or more than 10 miles for rural areas. Main Outcomes and Measures: BMI z score, obesity (age- and sex-specific BMI ≥95th percentile), and severe obesity (age- and sex-specific BMI ≥120% of the 95th percentile) from age 0 to 15 years. Results: Of 28 359 children (55 cohorts; 14 657 [51.7%] male and 13 702 [48.3%] female; 590 [2.2%] American Indian, Alaska Native, Native Hawaiian, or Other Pacific Islander; 1430 [5.4%] Asian; 4034 [15.3%] Black; 17 730 [67.2%] White; and 2592 [9.8%] other [unspecified] or more than 1 race; 5754 [20.9%] Hispanic and 21 838 [79.1%] non-Hispanic) with neighborhood food access data, 23.2% resided in low-income, low-food access neighborhoods in pregnancy and 24.4% in early childhood. After adjusting for individual sociodemographic characteristics, residence in low-income, low-food access (vs non-low-income, low-food access) neighborhoods in pregnancy was associated with higher BMI z scores at ages 5 years (ß, 0.07; 95% CI, 0.03-0.11), 10 years (ß, 0.11; 95% CI, 0.06-0.17), and 15 years (ß, 0.16; 95% CI, 0.07-0.24); higher obesity risk at 5 years (risk ratio [RR], 1.37; 95% CI, 1.21-1.55), 10 years (RR, 1.71; 95% CI, 1.37-2.12), and 15 years (RR, 2.08; 95% CI, 1.53-2.83); and higher severe obesity risk at 5 years (RR, 1.21; 95% CI, 0.95-1.53), 10 years (RR, 1.54; 95% CI, 1.20-1.99), and 15 years (RR, 1.92; 95% CI, 1.32-2.80). Findings were similar for residence in low-income, low-food access neighborhoods in early childhood. These associations were robust to alternative definitions of low income and low food access and additional adjustment for prenatal characteristics associated with child obesity. Conclusions: Residence in low-income, low-food access neighborhoods in early life was associated with higher subsequent child BMI and higher risk of obesity and severe obesity. We encourage future studies to examine whether investments in neighborhood resources to improve food access in early life would prevent child obesity.

Teaching gene-environment interaction concepts with narrative vignettes: Effects on knowledge, stigma, and behavior motivation.

Gene-environment interaction (GxE) concepts underlie a proper understanding of complex disease risk and risk-reducing behavior. Communicating GxE concepts is a challenge. This study designed an educational intervention that communicated GxE concepts in the context of eating behavior and its impact on weight, and tested its efficacy in changing knowledge, stigma, and behavior motivation. The study also explored whether different framings of GxE education and matching frames with individual eating tendencies would result in stronger intervention impact. The experiment included four GxE education conditions and a control condition unrelated to GxE concepts. In the education conditions, participants watched a video introducing GxE concepts then one of four narrative vignettes depicting how a character's experience with eating hyperpalatable or bitter tasting food (reward-based eating drive vs. bitter taste perception scenario) is influenced by genetic or environmental variations (genetic vs. environmental framings). The education intervention increased GxE knowledge, genetic causal attributions, and empathetic concern. Mediation analyses suggest that causal attributions, particularly to genetics and willpower, are key factors that drive downstream stigma and eating behavior outcomes and could be targeted in future interventions. Tailoring GxE education frames to individual traits may lead to more meaningful outcomes. For example, genetic (vs. environmental) framed GxE education may reduce stigma toward individuals with certain eating tendencies among individuals without such tendencies. GxE education interventions would be most likely to achieve desired outcomes such as reducing stigma if they target certain causal beliefs and are strategically tailored to individual attributes.

Green Space and Internalizing or Externalizing Symptoms Among Children.

Importance: Evidence suggests that living near green space supports mental health, but studies examining the association of green space with early mental health symptoms among children are rare. Objective: To evaluate the association between residential green space and early internalizing (eg, anxiety and depression) and externalizing (eg, aggression and rule-breaking) symptoms. Design, Setting, and Participants: Data for this cohort study were drawn from the Environmental Influences on Child Health Outcomes cohort; analysis was conducted from July to October 2023. Children born between 2007 and 2013 with outcome data in early (aged 2-5 years) and/or middle (aged 6-11 years) childhood who resided in 41 states across the US, drawing from clinic, hospital, and community-based cohorts, were included. Cohort sites were eligible if they recruited general population participants and if at least 30 children had outcome and residential address data to measure green space exposure. Nine cohorts with 13 sites met these criteria. Children diagnosed with autism or developmental delay were excluded, and 1 child per family was included. Exposures: Green space exposure was measured using a biannual (ie, summer and winter) Normalized Difference Vegetation Index, a satellite image-based indicator of vegetation density assigned to monthly residential history from birth to outcome assessment. Main Outcome and Measures: Child internalizing and externalizing symptoms were assessed using the Child Behavior Checklist for Ages 1½ to 5 or 6 to 18. The association between green space and internalizing and externalizing symptoms was modeled with multivariable linear regression using generalized estimating equations, adjusting for birthing parent educational level, age at delivery, child sex, prematurity, and neighborhood socioeconomic vulnerability. Models were estimated separately for early and middle childhood samples. Results: Among 2103 children included, 1061 (50.5%) were male; 606 (29.1%) identified as Black, 1094 (52.5%) as White, 248 (11.9%) as multiple races, and 137 (6.6%) as other races. Outcomes were assessed at mean (SD) ages of 4.2 (0.6) years in 1469 children aged 2 to 5 years and 7.8 (1.6) years in 1173 children aged 6 to 11 years. Greater green space exposure was associated with fewer early childhood internalizing symptoms in fully adjusted models (b = -1.29; 95% CI, -1.62 to -0.97). No associations were observed between residential green space and internalizing or externalizing symptoms in middle childhood. Conclusions and Relevance: In this study of residential green space and children's mental health, the association of green space with fewer internalizing symptoms was observed only in early childhood, suggesting a sensitive period for nature exposure. Policies protecting and promoting access to green space may help alleviate early mental health risk.

Parental perceptions of body weight and appetite in infants and toddlers with cystic fibrosis.

Nutritional status has clinical relevance and is a target of guidance to parents of children with cystic fibrosis (CF). Growth is routinely monitored in CF clinics but there is no standardized way of assessing appetitive behaviors or parents' perceptions of their children's appetite. Greater understanding of these factors could improve clinical guidance regarding parent feeding behaviors. We therefore aimed to assess parent perceptions of child weight, and parent reports of child appetite using the Baby Eating Behavior Questionnaire (BEBQ), in a sample of infants and toddlers with CF, compared with a community sample. We additionally assessed relationships of parent perceptions of child weight with parent feeding behaviors in the sample with CF. Anthropometric and questionnaire data were collected for 32 infants and toddlers with CF, as well as 193 infants and toddlers drawn from RESONANCE, a community cohort study. Parents perceived children with CF to be lower in weight than their actual weight, to a greater extent than was evident in the community sample. Parents who perceived their children with CF to be underweight vs. right weight reported greater slowness in eating on the BEBQ. Parents perceived children with CF to have greater slowness in eating and lower enjoyment of food, compared to parents of children in the community sample, independent of sample differences in child weight, age, and sex. Our results demonstrate the potential utility of the BEBQ in a clinical sample and suggest it may be helpful for clinicians to assess parents' perceptions of their child's weight and appetite to promote a fuller understanding of the child's nutritional status, facilitate appropriate feeding behaviors and alleviate unnecessary concerns.

Understanding risk and causal mechanisms for developing obesity in infants and young children: A National Institutes of Health workshop.

Obesity in children remains a major public health problem, with the current prevalence in youth ages 2-19 years estimated to be 19.7%. Despite progress in identifying risk factors, current models do not accurately predict development of obesity in early childhood. There is also substantial individual variability in response to a given intervention that is not well understood. On April 29-30, 2021, the National Institutes of Health convened a virtual workshop on "Understanding Risk and Causal Mechanisms for Developing Obesity in Infants and Young Children." The workshop brought together scientists from diverse disciplines to discuss (1) what is known regarding epidemiology and underlying biological and behavioral mechanisms for rapid weight gain and development of obesity and (2) what new approaches can improve risk prediction and gain novel insights into causes of obesity in early life. Participants identified gaps and opportunities for future research to advance understanding of risk and underlying mechanisms for development of obesity in early life. It was emphasized that future studies will require multi-disciplinary efforts across basic, behavioral, and clinical sciences. An exposome framework is needed to elucidate how behavioral, biological, and environmental risk factors interact. Use of novel statistical methods may provide greater insights into causal mechanisms.

FTO variation and early frontostriatal brain development in children.

OBJECTIVE: Common obesity-associated genetic variants at the fat mass and obesity-associated (FTO) locus have been associated with appetitive behaviors and altered structure and function of frontostriatal brain regions. The authors aimed to investigate the influence of FTO variation on frontostriatal appetite circuits in early life. METHODS: Data were drawn from RESONANCE, a longitudinal study of early brain development. Growth trajectories of nucleus accumbens and frontal lobe volumes, as well as total gray matter and white matter volume, by risk allele (AA) carrier status on FTO single-nucleotide polymorphism rs9939609 were examined in 228 children (102 female, 126 male) using magnetic resonance imaging assessments obtained from infancy through middle childhood. The authors fit functional concurrent regression models with brain volume outcomes over age as functional responses, and FTO genotype, sex, BMI z score, and maternal education were included as predictors. RESULTS: Bootstrap pointwise 95% CI for regression coefficient functions in the functional concurrent regression models showed that the AA group versus the group with no risk allele (TT) had greater nucleus accumbens volume (adjusted for total brain volume) in the interval of 750 to 2250 days (2-6 years). CONCLUSIONS: These findings suggest that common genetic risk for obesity is associated with differences in early development of brain reward circuitry and argue for investigating dynamic relationships among genotype, brain, behavior, and weight throughout development.

Biobehavioral susceptibility for obesity in childhood: Behavioral, genetic and neuroimaging studies of appetite.

Modern food environments are conducive to overeating and weight gain, but not everyone develops obesity. One reason for this may be that individuals differ in appetitive characteristics, or traits, that manifest early in life and go on to influence their behavioral susceptibility to gain and maintain excess weight. Classic studies showing that eating behavior in children can be measured by behavioral paradigms such as tests of caloric compensation and eating in the absence of hunger inspired the development and validation of psychometric instruments to assess appetitive characteristics in children and infants. A large body of evidence now suggests that food approach traits increase obesity risk, while food avoidant traits, such as satiety responsiveness, decrease obesity risk. Twin studies and genetic association studies have demonstrated that appetitive characteristics are heritable, consistent with a biological etiology. However, family environment factors are also influential, with mounting evidence suggesting that genetic and environmental risk factors interact and correlate with consequences for child eating behavior and weight. Further, neuroimaging studies are revealing that individual differences in responses to visual food cues, as well as to small tastes and larger amounts of food, across a number of brain regions involved in reward/motivation, cognitive control and other functions, may contribute to individual variation in appetitive behavior. Growing evidence also suggests that variation on psychometric measures of appetite is associated with regional differences in brain structure, and differential patterns of resting state functional connectivity. Large prospective studies beginning in infancy promise to enrich our understanding of neural and other biological underpinnings of appetite and obesity development in early life, and how the interplay between genetic and environmental factors affects appetitive systems. The biobehavioral susceptibility model of obesity development and maintenance outlined in this narrative review has implications for prevention and treatment of obesity in childhood.

Parent-reported child appetite moderates relationships between child genetic obesity risk and parental feeding practices.

Background: Food parenting practices are associated with child weight. Such associations may reflect the effects of parents' practices on children's food intake and weight. However, longitudinal, qualitative, and behavioral genetic evidence suggests these associations could, in some cases, reflect parents' response to children's genetic risk for obesity, an instance of gene-environment correlation. We tested for gene-environment correlations across multiple domains of food parenting practices and explored the role of parent-reported child appetite in these relationships. Materials and methods: Data on relevant variables were available for N = 197 parent-child dyads (7.54 ± 2.67 years; 44.4% girls) participating in RESONANCE, an ongoing pediatric cohort study. Children's body mass index (BMI) polygenic risk score (PRS) were derived based on adult GWAS data. Parents reported on their feeding practices (Comprehensive Feeding Practices Questionnaire) and their child's eating behavior (Child Eating Behavior Questionnaire). Moderation effects of child eating behaviors on associations between child BMI PRS and parental feeding practices were examined, adjusting for relevant covariates. Results: Of the 12 parental feeding practices, 2 were associated with child BMI PRS, namely, restriction for weight control (ß = 0.182, p = 0.011) and teaching about nutrition (ß = -0.217, p = 0.003). Moderation analyses demonstrated that when children had high genetic obesity risk and showed moderate/high (vs. low) food responsiveness, parents were more likely to restrict food intake to control weight. Conclusion: Our results indicate that parents may adjust their feeding practices in response to a child's genetic propensity toward higher or lower bodyweight, and the adoption of food restriction to control weight may depend on parental perceptions of the child's appetite. Research using prospective data on child weight and appetite and food parenting from infancy is needed to further investigate how gene-environment relationships evolve through development.

Milkshake Acutely Stimulates Dopamine Release in Ventral and Dorsal Striatum in Healthy-Weight Individuals and Patients with Severe Obesity Undergoing Bariatric Surgery: A Pilot Study.

The overconsumption of palatable energy-dense foods drives obesity, but few human studies have investigated dopamine (DA) release in response to the consumption of a palatable meal, a putative mediator of excess intake in obesity. We imaged [11C]raclopride in the brain with positron emission tomography (PET) to assess striatal dopamine (DA) receptor binding pre- and post-consumption of a highly palatable milkshake (250 mL, 420 kcal) in 11 females, 6 of whom had severe obesity, and 5 of whom had healthy-weight. Those with severe obesity underwent assessments pre- and 3 months post-vertical sleeve gastrectomy (VSG). Our results demonstrated decreased post- vs. pre-meal DA receptor binding in the ventral striatum (p = 0.032), posterior putamen (p = 0.012), and anterior caudate (p = 0.018), consistent with meal-stimulated DA release. Analysis of each group separately suggested that results in the caudate and putamen were disproportionately driven by meal-associated changes in the healthy-weight group. Baseline (pre-meal) DA receptor binding was lower in severe obesity than in the healthy-weight group. Baseline DA receptor binding and DA release did not change from pre- to post-surgery. The results of this small pilot study suggest that milkshake acutely stimulates DA release in the ventral and dorsal striatum. This phenomenon likely contributes to the overconsumption of highly palatable foods in the modern environment.

Paediatric obesity and metabolic syndrome associations with cognition and the brain in youth: Current evidence and future directions.

Obesity and components of the metabolic syndrome (MetS) are associated with differences in brain structure and function and in general and food-related cognition in adults. Here, we review evidence for similar phenomena in children and adolescents, with a focus on the implications of extant research for possible underlying mechanisms and potential interventions for obesity and MetS in youth. Current evidence is limited by a relative reliance on small cross-sectional studies. However, we find that youth with obesity and MetS or MetS components show differences in brain structure, including alterations in grey matter volume and cortical thickness across brain regions subserving reward, cognitive control and other functions, as well as in white matter integrity and volume. Children with obesity and MetS components also show some evidence for hyperresponsivity of food reward regions and hyporesponsivity of cognitive control circuits during food-related tasks, altered brain responses to food tastes, and altered resting-state connectivity including between cognitive control and reward processing networks. Potential mechanisms for these findings include neuroinflammation, impaired vascular reactivity, and effects of diet and obesity on myelination and dopamine function. Future observational research using longitudinal measures, improved sampling strategies and study designs, and rigorous statistical methods, promises to further illuminate dynamic relationships and causal mechanisms. Intervention studies targeted at modifiable biological and behavioural factors associated with paediatric obesity and MetS can further inform mechanisms, as well as test whether brain and behaviour can be altered for beneficial outcomes.

The Development of Appetite: Tracking and Age-Related Differences in Appetitive Traits in Childhood.

Appetitive traits are associated with body weight. Increased understanding of how appetitive traits evolve from early life could advance research on obesity risk and inform intervention development. We report on tracking and age-related differences in appetitive traits in childhood within the RESONANCE cohort. Parents of RESONANCE children aged 6.02 ± 2.99 years completed the Child Eating Behavior Questionnaire (CEBQ). Pearson correlations of appetitive traits and age were tested for all participants contributing at least one observation, using each participant's first observation (N = 335). Children's first and second observations of the CEBQ (n = 127) were used to test tracking (paired correlations) and age-related differences (paired t-tests) within individuals. CEBQ correlations with age suggested that satiety responsiveness, slowness in eating, emotional undereating, and desire to drink decreased with age (r = -0.111 to r = -0.269, all p < 0.05), while emotional overeating increased with age (r = 0.207, p < 0.001). Food fussiness demonstrated a quadratic relationship with age. Paired t-tests further supported an increase in emotional overeating with age (M: 1.55 vs. 1.69, p = 0.005). All CEBQ subscales demonstrated moderate to high tracking (r = 0.533 to r = 0.760, p < 0.001). Our initial findings within the RESONANCE cohort suggest that food avoidant traits are negatively related with age, while emotional overeating increases with age, and that appetitive traits track through childhood.

Using Educational Videos and Perspective-Taking to Communicate Gene-By-Environment Interaction Concepts about Eating Behavior: Effects on Empathy and Weight Stigma.

OBJECTIVE: This study investigated whether education about gene-by-environment interaction (G × E) concepts could improve G × E knowledge and positively affect empathy and weight stigma. DESIGN: We conducted a randomized trial using a 2 × 2 between-subjects design. SETTING: Online. PARTICIPANTS: Five hundred eighty-two American participants from the Prolific platform. INTERVENTION: Participants were randomly assigned to watch an educational or a control video. Participants then watched a set of vignette scenarios that depicted what it is like to have a predisposition toward obesogenic eating behaviors from either a first-person or third-person perspective. MAIN OUTCOME MEASURE(S): Participants completed questionnaires measuring G × E knowledge, causal attributions, weight stigma, and empathy postintervention. ANALYSIS: Two-by-two between-subjects ANOVAs and exploratory mediation analyses were conducted. RESULTS: Participants who watched the educational video demonstrated greater G × E knowledge, reported higher empathy toward the characters in the vignette scenarios and held fewer stigmatizing attitudes (notably blame) toward individuals with higher weight. Exploratory mediation analyses indicated that the educational video led to these positive downstream effects by increasing the extent to which participants attributed genetic causes to eating behaviors. CONCLUSIONS AND IMPLICATIONS: Education about G × E causes of eating behaviors can have beneficial downstream effects on attitudes toward people with higher weight.

Neurobehavioral phenotypes of delay discounting and cognitive control in child attention-deficit/hyperactivity disorder and obesity: Shared or distinct?

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) and obesity have been independently associated with deficient cognitive control (CC) and heightened preference for immediate reward. OBJECTIVES: We aimed to identify specific shared and distinct neurobehavioral phenotypes of child obesity and ADHD by simultaneously measuring CC and preference for immediate reward in children with and without ADHD who varied in body weight. METHODS: This case-control study included 323 8-12 year olds (ADHD n = 215, typically developing (TD) screened for ADHD symptoms [TD] controls n = 108) varying in body weight. Children completed a go/no-go task (assessing CC), as well as a classical money delay discounting (DD) task and novel experiential game time DD task (assessing preference for immediate over delayed rewards). RESULTS: For game time DD, there was a body mass index z-score (BMIz)*ADHD interaction, such that TD children with overweight/obesity showed game time DD levels that were greater than those of TD children without overweight/obesity and similar to those of children with ADHD. Only children with ADHD showed poorer CC compared to TD children, with no effects of body weight. CONCLUSIONS: Heightened game time DD with delays and rewards experienced in real-time may represent a neurobehavioral phenotype that is shared between ADHD and overweight/obesity in childhood, whereas deficient CC may be specific to children with ADHD.

The relationship between weight loss and cognitive function in bariatric surgery.

BACKGROUND: Previously, we reported short-term improvements in auditory attention, oromotor processing speed, and executive function during the active weight loss phase following bariatric surgery that persisted out to 3 months. In this study, our aims were to investigate the relationship between weight loss and cognitive performance in these patients 1 year following vertical sleeve gastrectomy (VSG) and Roux-en Y gastric bypass (RYGB) surgery and to determine whether preoperative cognitive performance predicted weight loss. METHODS: Adult women ages 18-55 approved for bariatric surgery completed a cognitive battery prior to and at 2, 12, 24, and 52 weeks following VSG (N = 17) or RYGB (N = 18). Scores from each task were assigned to one of the following cognitive domains: auditory attention, processing speed, memory, and executive functioning. Weight loss and cognitive scores for each domain were calculated and compared between cohorts. RESULTS: RYGB surgery resulted in greater weight loss at 1-year follow-up relative to VSG. Both VSG and RYGB procedures resulted in improved performance on different measures of auditory attention and both surgery groups improved across all processing speed tasks. Within the executive function domain, both groups showed improvements, but only the RYGB procedure resulted in improved performance in the Trail Making Test. Baseline auditory attention and memory performance predicted weight loss at 1 year following RYGB but not VSG surgery. Controlling for baseline cognitive performance, percent total weight loss predicted auditory attention at 1 year following RYGB but not VSG surgery. CONCLUSIONS: Bariatric surgery type may result in selective improvements in cognition during the first year following surgery. Presurgical cognitive performance as well as surgery type appears to influence weight loss outcomes.

Obesity and acute stress modulate appetite and neural responses in food word reactivity task.

Obesity can result from excess intake in response to environmental food cues, and stress can drive greater intake and body weight. We used a novel fMRI task to explore how obesity and stress influenced appetitive responses to relatively minimal food cues (words representing food items, presented similarly to a chalkboard menu). Twenty-nine adults (16F, 13M), 17 of whom had obesity and 12 of whom were lean, completed two fMRI scans, one following a combined social and physiological stressor and the other following a control task. A food word reactivity task assessed subjective food approach (wanting) as well as food avoidant (restraint) responses, along with neural responses, to words denoting high energy-density (ED) foods, low-ED foods, and non-foods. A multi-item ad-libitum meal followed each scan. The obese and lean groups demonstrated differences as well as similarities in activation of appetitive and attention/self-regulation systems in response to food vs. non-food, and to high-ED vs. low-ED food words. Patterns of activation were largely similar across stress and non-stress conditions, with some evidence for differences between conditions within both obese and lean groups. The obese group ate more than the lean group in both conditions. Our results suggest that neural responses to minimal food cues in stressed and non-stressed states may contribute to excess consumption and adiposity.

Investigating relationships between post-prandial gut hormone responses and taste liking ratings prior to and following bariatric surgery: a pilot study.

BACKGROUND: Alterations in gut hormone secretion and reported changes in taste preferences have been suggested to contribute to the weight-reducing effects of bariatric surgery. However, a link between changes in gut hormone secretion and taste preferences following bariatric surgery has yet to be elucidated. METHODS: Here we examined the potential relationships between gut hormone responses (GLP-1 and PYY3-36 peak, ghrelin trough) to a test meal of Ensure and liking ratings for taste mixtures varying in sugar and fat content before and following bariatric surgery (vertical sleeve gastrectomy (VSG): N = 4; Roux-en Y gastric bypass (RYGB): N = 8). RESULTS: Significant increases in GLP-1 and PYY3-36 peak and a significant drop in ghrelin trough were observed following surgery. Pre- and postoperation, patients with higher postprandial GLP-1 or PYY3-36 peaks gave lower liking ratings for mixtures containing a combination of fat and sugar (half and half + 20% added sugar) whereas, for the combined surgery analyses, no relationships were found with solutions comprised of high fat (half and half + 0% sugar), predominantly high sugar (skim milk + 20% added sugar), or low fat and low sugar (skim milk + 0% added sugar). Within the RYGB patients, patients with the greatest increase in postprandial GLP-1 peak from preoperation to postoperation also demonstrated the greatest decrease in liking for half & half + 20% added sugar and skim milk + 20% added sugar, but not the unsweetened version of each solution. No pre- or postoperative relationship between ghrelin and liking ratings were observed. CONCLUSION: Gut hormone responses following bariatric surgery may contribute to taste processing of sugar+fat mixtures and together influence weight loss.

Time of day differences in appetite and gut hormone responses to meal and stress challenges in adults with normal-weight and obesity.

BACKGROUND: Lifestyle factors like time of eating and stress exposure may impact physiology to promote excess weight gain. To understand behavioral and physiological mechanisms underlying these potential effects, we compared appetite and gut hormone responses to a series of meal and stress challenges beginning in the morning and the afternoon, in adults with normal-weight and obesity. METHOD: Thirty-two adults (16 with normal-weight, 16 with obesity) underwent the same test protocol on different days, each following an 8 h fast. On one day the protocol began in the morning (AM condition); on the other day it began in the late afternoon (PM condition). On each day they first received a standardized liquid meal (9:00am/4:00pm), then a stress test (Socially-Evaluated Cold Pressor Test, 11:10am/6:10pm), then an ad libitum buffet meal (11:40am/6:40pm). Appetite and stress ratings were obtained, and blood was drawn for measures of ghrelin, PYY, GLP-1, insulin, glucose, cortisol and leptin. Acetaminophen was administered as a tracer to assess gastric emptying of the liquid meal. RESULTS: Across all three challenges, AUC cortisol was lower in the PM vs. AM condition (all p<.001), and AUC insulin and leptin were higher in the obesity vs. normal-weight group (all p<.001). For the standardized liquid meal only, AUC hunger, desire to eat and ghrelin were greater in the PM vs. AM condition (all p<0.05), and AUC ghrelin was lower in the obesity vs. normal-weight group, even when controlling for baseline values (p<0.05). AUC glucose was higher in the evening for the normal-weight group only (condition x group interaction p<0.05). Post-liquid meal gastric emptying as indexed by AUC acetaminophen was slower in the PM vs. AM (p<.01). For the stress test, AUC cortisol was lower in the PM than the AM condition even when controlling for baseline values (p<.05). AUC leptin was lower in the evening in the obesity group only (condition x group interaction p<0.01). PYY showed an acute decrease post-stressor in the normal-weight but not the obesity group (p<.05). Post-stress ad libitum buffet meal intake was similar in the evening and morning conditions, and higher in the obesity group (p<0.05). Only among the obesity group in the evening condition, higher stressor-associated stress and cortisol were associated with greater meal-associated appetite (p<0.05). CONCLUSIONS: Normal-weight individuals and those with obesity may be at risk of evening overeating as a result of differential appetite and gut hormone responses following meal intake and stress exposure.