Executive functions predict weight loss in a medically supervised weight loss programme

Towards precision medicine in bariatric surgery prescription

Obesity is a complex, multifactorial and chronic disease. Bariatric surgery is a safe and effective treatment intervention for obesity and obesity-related diseases. However, weight loss after surgery can be highly heterogeneous and is not entirely predictable, particularly in the long-term after intervention. In this review, we present and discuss the available data on patient-related and procedure-related factors that were previously appointed as putative predictors of bariatric surgery outcomes. In addition, we present a critical appraisal of the available evidence on which factors could be taken into account when recommending and deciding which bariatric procedure to perform. Several patient-related features were identified as having a potential impact on weight loss after bariatric surgery, including age, gender, anthropometrics, obesity co-morbidities, eating behavior, genetic background, circulating biomarkers (microRNAs, metabolites and hormones), psychological and socioeconomic factors. However, none of these factors are sufficiently robust to be used as predictive factors. Overall, there is no doubt that before we long for precision medicine, there is the unmet need for a better understanding of the socio-biological drivers of weight gain, weight loss failure and weight-regain after bariatric interventions. Machine learning models targeting preoperative factors and effectiveness measurements of specific bariatric surgery interventions, would enable a more precise identification of the causal links between determinants of weight gain and weight loss. Artificial intelligence algorithms to be used in clinical practice to predict the response to bariatric surgery interventions could then be created, which would ultimately allow to move forward into precision medicine in bariatric surgery prescription.

Body mass index, systemic inflammation and cognitive performance in adolescents: A cross-sectional study

BACKGROUND

Excessive body weight has been related to lower cognitive performance. One of the mechanisms through which excess body weight may affect cognition is inflammation.

HYPOTHESIS

Our hypothesis is that both body mass index (BMI) and circulating levels of inflammatory biomarkers will be negatively related to cognitive performance.

DESIGN

Cross-sectional study.

SETTING

Users of the public health centres of the Consorci Sanitari de Terrassa (Terrassa, Spain) between 2010 and 2017 aged 12-21 years.

PARTICIPANTS

One hundred and five adolescents (46 normoweight, 18 overweight, 41 obese).

MEASUREMENTS

Levels of high sensitivity C-reactive protein, interleukin 6, tumour necrosis factor α (TNFα) and fibrinogen were determined from blood samples. Cognitive performance was evaluated and six cognitive composites were obtained: working memory, cognitive flexibility, inhibitory control, decision-making, verbal memory, and fine motor speed. A single multivariate general lineal model was used to assess the influence of the four inflammatory biomarkers, as well as participants' BMI, sex, and age on the 6 cognitive indexes.

RESULTS

An inverse relationship between BMI and inhibitory control (F = 5.688, p = .019; β = -0.212, p = .031), verbal memory (F = 5.404, p = .022; β = -0.255, p = .009) and fine motor speed (F = 9.038, p = .003; β = -0.319, p = .001) was observed. Levels of TNFα and fibrinogen were inversely related to inhibitory control (F = 5.055, p = .027; β = -0.226, p = .021) and verbal memory (F = 4.732, p = .032; β = -0.274, p = .005), respectively.

LIMITATIONS

The cross-sectional nature of the study, the use of cognitive tests designed for clinical purposes, and the use of BMI as a proxy for adiposity are limitations of our study that must be taken into account when interpreting results.

CONCLUSIONS

Our data indicate that some components of executive functions, together with verbal memory, are sensitive to specific obesity-related inflammatory agents at early ages.

Cognitive Control and Weight Loss After Bariatric Surgery: the BARICO Study

BACKGROUND AND OBJECTIVES

Bariatric surgery (BS) is an effective treatment for obesity. However, some individuals experience insufficient weight loss after surgery. Therefore, we investigated whether cognitive control affects weight loss after Roux-en-Y gastric bypass (RYGB).

METHODS

Within this exploratory observational study, part of the BARICO study (BAriatric surgery Rijnstate and Radboudumc neuroImaging and Cognition in Obesity), participants aged between 35 and 55 years eligible for RYGB were included. Before and after BS, body weight, (delta) BMI and percentage total body weight loss (%TBWL) were determined. Additionally, at baseline, Stroop task-performance, -activation and -connectivity were assessed by a color-word paradigm task during functional neuroimaging to determine the ability of participants to inhibit cognitive interference.

RESULTS

Seventy-six participants were included, of whom 14 were excluded from fMRI analysis, leaving 62 participants. Participants were aged 45.0 ± 5.9 years with a mean pre-surgery BMI of 40.2 ± 3.3 kg/m2, and 86% were women. Mean decrease in BMI was 13.8 ± 2.5 kg/m2, and mean %TBWL was 34.9 ± 6.3% 1 year after BS. Stroop task performance did not correlate with (delta) BMI and %TBWL. The inferior parietal/middle occipital gyrus, inferior frontal gyrus, and supplementary motor cortex were involved in cognitive interference, although activity in these regions did not predict weight loss after surgery. Lastly, generalized psychophysiological interaction did not provide evidence for (delta) BMI- and %TBWL-dependent connectivity modulation.

DISCUSSION

Cognitive control did not predict weight loss after surgery. Future studies should focus on longer follow-up periods to understand the relation between cognitive control and weight loss.

TRIAL REGISTRATION

NL7090 ( https://www.clinicaltrialregister.nl/nl/trial/28949 ).

Pre-post intervention exploring cognitive function and relationships with weight loss, intervention adherence and dropout

Objective

To evaluate the association between baseline cognitive function, intervention dropout, adherence and 3-month weight loss (WL) when controlling for confounding demographic variables.

Methods

107 (Mage = 40.9 yrs.), BMI in the overweight and obese range (BMI = 35.6 kg/m²), men (N = 17) and women (N = 90) completed a 3-month WL intervention. Participants attended weekly behavioral sessions, comply with a reduced calorie diet, and complete 100 min of physical activity (PA)/wk. Cognitive function tasks at baseline included Flanker (attention), Stroop (executive control) and working memory, demographics, body weight and cardiovascular fitness were assessed at baseline. Session attendance, adherence to PA and diet were recorded weekly.

Results

Baseline attention was positively correlated with age (p < .05), education (p < .05), attendance (p < .05), diet (p < .05) and PA (p < .05). Baseline executive control (p < .05) and working memory (p < .05) were each associated with % WL. Baseline executive control (p < .01) and working memory (p < .001) were also each associated with education. ANOVA indicated that baseline attention (p < .01) was associated with WL, specifically for comparing those who achieved 5-10% WL (p < .01) and those who achieved greater than 10% WL (p < .01) to those who dropped.

Significance

Results suggest that stronger baseline attention is associated with completion of a 3-mo. WL intervention. Executive control and working memory are associated with amount of WL achieved.

NCT registration

US NIH Clinical Trials, NCT01664715.

Context Matters: Preliminary Evidence That the Association between Positive Affect and Adiposity in Infancy Varies in Social vs. Non-Social Situations

Previous studies have suggested that infants high in negative affect have higher levels of adiposity, arising in part via changes in nutrition (e.g., “feeding to soothe”). Few studies have examined whether positive affect shows similar or inverse associations with adiposity. The current study examined cross-sectional and longitudinal relationships between adiposity and observations of positive affect in both a social and a non-social context, using data from infants at four (n = 125) and 12 (n = 80) months of age. Our analyses did not find any cross-sectional associations between positive affect and adiposity (all p > 0.05). However, in the longitudinal analyses, positive affect in a non-social context, when observed at four months of age, was positively associated with weight-for-length at 12 months of age (zWFL; ß = 1.49, SE = 0.67, p = 0.03), while positive affect observed at four months of age in a social context was inversely associated with body fat percentage at 12 months of age (ß = −11.41, SE = 5.44, p = 0.04). These findings provide preliminary evidence that the p positive affect is related to adiposity in infancy and suggest that the direction of association (i.e., direct or inverse) may be specific to the context in which positive affect is measured. Future research should examine the role of nutritional status in any relationships between adiposity and emotion at this early stage.

High-Level Executive Functions: A Possible Role of Sex and Weight Condition in Planning and Decision-Making Performances

Evidence indicates an association between executive functioning and increased weight, with different patterns ascribed to individual differences (sex, age, lifestyles). This study reports on the relationship between high-level executive functions and body weight. Sixty-five young adults participated in the study: 29 participants (14 males, 15 females) in the normal weight range; 36 participants (18 males, 18 females) in the overweight range. The Iowa Gambling Task (IGT) and Tower of London Task were administered to assess decision making and planning. Planning did not differ in individuals in the normal-weight and overweight groups, and no difference emerged between females and males. However, normal and overweight males and females had different patterns in decision making. On the long-term consequences index of the IGT, females reported lower scores than males. Males in the overweight range had a lower long-term consequences index on the IGT than normal-weight males, while this pattern did not emerge in females. These findings suggest that decision-making responses may differ in the overweight relative to healthy weight condition, with a different expression in males and females. This pattern should be considered in weight loss prevention strategies, possibly adopting different approaches in males and females.

Contrasting dorsal caudate functional connectivity patterns between frontal and temporal cortex with BMI increase: link to cognitive flexibility

BACKGROUND

Obesity is associated with brain intrinsic functional reorganization. However, little is known about the BMI-related interhemispheric functional connectivity (IHFC) alterations, and their link with executive function in young healthy adults.

METHODS

We examined voxel-mirrored homotopic connectivity (VMHC) patterns in 417 young adults from the Human Connectome Project. Brain regions with significant association between BMI and VMHC were identified using multiple linear regression. Results from these analyses were then used to determine regions for seed-voxel FC analysis, and multiple linear regression was used to explore the brain regions showing significant association between BMI and FC. The correlations between BMI-related executive function measurements and VMHC, as well as seed-voxel FC, were further examined.

RESULTS

BMI was negatively associated with scores of Dimensional Change Card Sort Test (DCST) assessing cognitive flexibility (r = -0.14, p = 0.006) and with VMHC of bilateral inferior parietal lobule, insula and dorsal caudate. The dorsal caudate emerged as a nexus for BMI-related findings: greater BMI was associated with greater FC between caudate and hippocampus and lower FC between caudate and several prefrontal nodes (right inferior frontal gyrus, anterior cingulate cortex, and middle frontal gyrus). The FC between right caudate and left hippocampus was negatively associated with scores of DCST (r = -0.15, p = 0.0018).

CONCLUSIONS

Higher BMI is associated with poorer cognitive flexibility performance and IHFC in an extensive set of brain regions implicated in cognitive control. Larger BMI was associated with higher caudate-medial temporal lobe FC and lower caudate-dorsolateral prefrontal cortex FC. These findings may have relevance for executive function associated with weight gain among otherwise healthy young adults.

The clinical obesity maintenance model: a structural equation model

PURPOSE

Theoretical research on the psychological underpinnings of weight management is limited. Recently, the clinical obesity maintenance model (COMM) proposed a theoretical conceptualisation of salient psychological and neuropsychological mechanisms maintaining weight management issues. The current study aimed to empirically test the COMM and elucidate the results in the context of recent empirical findings.

METHODS

Participants (N = 165) were recruited from university and community settings in Australia. The sample consisted of adults with normal weight (n = 41), overweight (n = 40), and obesity (n = 84). Participants completed self-report questionnaires and a brief neuropsychological test. Structural equation modelling was used to estimate the associations between the hypothesised variables of the COMM and evaluate the model fit.

RESULTS

Findings suggested acceptable to good model fit. Furthermore, several direct effects were found. First, cognitive flexibility directly affected eating habit strength. Second, eating habit strength directly affected eating beliefs. Third, eating beliefs directly affected emotion dysregulation. Fourth, emotion dysregulation directly affected depression and binge eating with depression partially mediating this relationship. Finally, depression directly affected binge eating.

CONCLUSION

This was the first study to empirically test the COMM. Overall, findings provide preliminary support for the COMM as a psychological model of weight management and highlight the underlying psychological and neuropsychological mechanisms that may contribute to weight management issues. As this study examined a simplified version of the COMM, future research should continue evaluating this model and consider incorporating these components into more holistic weight management models to improve long-term treatment outcomes.

LEVEL OF EVIDENCE

V, cross-sectional descriptive study.

Targeting executive function for weight loss in adults with overweight or obesity

Obesity is associated with a multitude of negative health sequalae. Behavioral weight loss (BWL) is currently the recommended behavioral treatment for obesity; however, it is not effective for approximately half of the individuals who participate. BWL requires individuals to carry out many tasks requiring executive function (EF; i.e., higher order cognitive functions such as planning and problem solving) in order to be successful. Growing research supports that lower EF may be associated with attenuated weight loss following BWL, and targeting EF in treatment could improve outcomes. This paper aims to describe the rationale for the development of Novel Executive Function Training for Obesity (NEXT), which adapts Compensatory Cognitive Training to be delivered in conjunction with BWL. We summarize evidence relating EF to obesity and reduced weight loss following BWL, as well as the past success of cognitive training on EF. Then we describe the treatment model for NEXT followed by initial data suggesting that NEXT is feasible and acceptable and may impact EF and weight. Obesity treatments incorporating cognitive training, especially those that train compensatory strategies, may improve weight-loss outcomes and provide a more durable treatment than traditional interventions, but larger randomized control trials are necessary.

Unravelling the impacts of western-style diets on brain, gut microbiota and cognition

The steady rise in the prevalence of obesity has been fostered by modern environments that reduce energy expenditure and encourage consumption of 'western'-style diets high in fat and sugar. Obesity has been consistently associated with impairments in executive function and episodic memory, while emerging evidence indicates that high-fat, high-sugar diets can impair aspects of cognition within days, even when provided intermittently. Here we review the detrimental effects of diet and obesity on cognition and the role of inflammatory and circulating factors, compromised blood-brain barrier integrity and gut microbiome changes. We next evaluate evidence for changing risk profiles across life stages (adolescence and ageing) and other populations at risk (e.g. through maternal obesity). Finally, interventions to ameliorate diet-induced cognitive deficits are discussed, including dietary shifts, exercise, and the emerging field of microbiome-targeted therapies. With evidence that poor diet and obesity impair cognition via multiple mechanisms across the human lifespan, the challenge for future research is to identify effective interventions, in addition to diet and exercise, to prevent and ameliorate adverse effects.

Pilot Trial of Acceptance-Based Behavioral Weight Loss and Neurocognition Among American Indians

Acceptance-based behavioral therapies (ABTs) for obesity may be superior to standard behavioral therapies but have not been adequately tested with American Indians (AIs). Neurocognitive function is also unexamined in relation to behavioral weight loss among AIs despite findings that neurocognition predicts outcomes in general samples, may help explain some of the benefits of ABTs, and may be relevant to marginalized groups. The primary objective of this pilot was to examine the feasibility/acceptability of ABT in an AI sample. Exploratory analyses examined the relationship between neurocognition and weight loss. Forty-eight AI adults with overweight/obesity (ages 43.3 ± 10.3 years, 85% female; baseline body mass index = 36.8 ± 4.4 kg/m²) enrolled in a 6-month open ABT weight loss trial. Feasibility indices, including screening/enrollment, session attendance, retention rates for posttreatment assessments, and program acceptability were examined. Percent weight loss (%WL) was assessed as well as fluid and crystalized neurocognition (National Institutes of Health Toolbox Cognition Battery [NIHTB-CB]). We enrolled 79% of the eligible sample and retained 75% (N = 36) at posttreatment assessments. Program completers lost an average of 5.2 ± 4.9% of initial body weight (d_z = 1.14), whereas intent-to-treat analyses show a mean loss of 4.1 ± 4.7%. Participants reported high satisfaction, effectiveness, and cultural appropriateness. Exploratory analyses of neurocognitive domains suggested that crystalized cognition was higher among completers, and higher baseline cognitive flexibility predicted greater %WL (β = .34, p = .05). ABT resulted in clinically significant weight loss in an AI sample. A controlled trial of ABT in a larger, more diverse sample is warranted to determine whether (a) the findings are robust, generalizable, and/or superior to other treatments and (b) neurocognitive factors moderate outcomes.

Executive Functions in Predicting Weight Loss and Obesity Indicators: A Meta-Analysis

While previous studies have suggested that there exists a relationship between obesity and executive function (EF), the mechanisms and causal relationship between them remain unclear. There are important clinical implications of determining whether EF can predict and treat obesity. We conducted a multilevel meta-analysis of randomized controlled trials (RCTs) and longitudinal studies. Specifically, we investigate (a) whether EF interventions have an effect on weight loss, (b) whether baseline EF can be a predictor of future weight loss through obesity intervention, and (c) whether early-life EF can predict future weight loss. Eight RCTs and 17 longitudinal studies with a total of 11,393 participants were identified. We found that (a) EF interventions may not have an effect on weight loss, (b) baseline inhibition (β = 0.259, p = 0.03) and delay discounting (β = −0.17, p = 0.04) significantly predict future weight loss through obesity intervention, (c) age (F = 13.666, p = 0.005) moderates the relationship between working memory and weight loss through intervention, but not weight status, type of intervention, and percentage of female, and (d) early life inhibition (β = 0.185, p = 0.07) is a marginally significant predictor of future weight loss. Our results seem to support the assumption that the relationship between EF and obesity is not direct, and a higher-order factor, such as genes, may link obesity and EF. Building on the preliminary findings, further studies focusing on EF and obesity are needed in the future.

Cognitive Training: Associations and Implications for Weight Management and Translational Research

Behavioral weight loss programs combining energy restriction and increased physical activity (PA) are generally successful in producing clinically significant weight loss (≥5%) over 3-6 mos. However, weight maintenance (≥ 2 yrs.) continues to be problematic, due in part to an inability of individuals to continue adherence to diet and PA recommendations. It is hypothesized that neurocognitive processes, specifically executive functions (EFs, i.e., inhibition, working memory, mental flexibility), underlie self-regulation, self-efficacy, and are essential for the adoption and maintenance of health behaviors. Behavioral weight loss programs generally attempt to improve self-regulation; however, these skills are difficult to implement long-term. Strengthening EFs through cognitive training may improve weight maintenance by improving self-efficacy and self-regulation, resulting in improved program attendance and improved adherence to dietary and PA recommendations. Although randomized trials have not been conducted to specifically evaluate this hypothesis, results from the available literature suggest the potential for cognitive training to improve weight maintenance.

Executive Functioning as a Predictor of Weight Loss and Physical Activity Outcomes

BACKGROUND

Executive functioning, which is fundamental for carrying out goal-directed behaviors, may be an underappreciated predictor of outcomes in lifestyle modification programs for adults with obesity.

PURPOSE

This study tested the hypotheses that higher levels of baseline executive functioning would predict greater weight loss and physical activity after 6 months of behavioral treatment.

METHODS

Participants (N = 320) were recruited from the community and provided with 16 treatment sessions. Executive functioning was measured with the tower task component of the Delis-Kaplan Executive Function System (D-KEFS). At months 0 and 6, weight was measured in the clinic and physical activity was measured with tri-axial accelerometers.

RESULTS

Baseline D-KEFS achievement score, rule violations, and completion time significantly predicted weight loss at 6 months. For example, among participants without any rule violations (n = 162), weight loss averaged 11.0%, while those with rule violations (n = 158) averaged 8.7% weight loss. Rule violations also significantly predicted physical activity at 6 months. Among participants without any rule violations, physical activity at 6 months averaged 169.8 min/week, versus 127.2 min/week among those with rule violations.

CONCLUSIONS

Particular aspects of executive functioning may predict the relative ease or difficulty of changing eating and exercise-related behaviors, albeit with small effect sizes. This study is the first to our knowledge to detect a predictive relationship between components of executive functioning and objectively measured physical activity in adult lifestyle modification, and one of the first to predict weight loss in adults using an objective measure of executive functioning.

CLINICALTRIALS.GOV REGISTRATION NUMBER

NCT02363010.

Diet, inflammation and the gut microbiome: Mechanisms for obesity-associated cognitive impairment

Poor diet and obesity are associated with cognitive impairment throughout adulthood, and increased dementia risk in aging. Here we review the current literature interrogating the mechanisms by which diets high in fat, or fat and sugar lead to cognitive impairment, focusing on changes to gut microbiome composition, inflammatory signalling and blood-brain barrier integrity. Preclinical studies indicate weight gain is not necessary for diet-induced cognitive impairment. Rather, gut microbiome composition, and systemic and central inflammatory processes appear to contribute to diet-induced cognitive impairment. While both obese humans and rodents exhibit reduced blood-brain barrier integrity, cognitive impairments precede these changes, suggesting other mechanisms may underly diet-induced cognitive changes. Other potential candidates include hormone, glucoregulatory and cardiovascular changes. Poor diet and obesity act through multiple mechanisms to affect cognitive health and the challenge for future research is to identify key processes that can be reversed to improve cognition and quality of life.

Adverse childhood experiences and cognitive function among adults with excess adiposity

BACKGROUND

Adverse childhood experiences (ACEs) and obesity are independently associated with brain/neurocognitive health. Despite a growing emphasis on the importance of early life adversity on health, the relationship between ACEs and neurocognition in adults with overweight/obesity is unclear. The objective was to examine associations between self-reported ACEs and measured neurocognitive domains in a sample of adults with overweight/obesity.

METHODS

Participants were 95 predominantly white, highly educated adult women (76% female, 81% Caucasian, and 75% ≥ bachelor's degree) with excess adiposity enrolled in the Cognitive and Self-regulatory Mechanisms of Obesity Study. ACEs and fluid/crystallized neurocognitive domains were measured at baseline using the Adverse Childhood Experiences Scale and the NIH Toolbox Cognition Battery and Automated Neuropsychological Assessment Metric, respectively.

RESULTS

Higher ACEs scores were negatively correlated with fluid cognition (r = -.34, P < .001) but not crystallized cognition (r = .01, ns). Individuals with 3 and 4+ ACEs displayed significantly lower fluid cognition scores than those with fewer ACEs F 4,89 = 3.24, P < .05. After accounting for body mass index (BMI), age, sex, race, and education, higher ACEs scores were still associated with poorer performance on overall fluid cognition (β = -.36, P < .01), along with the following subtests: Stroop Colour/Word test (β = -.23, P < .05), Go/No-Go omissions (β = .29, P < .01), and Picture Sequence Memory task (β = -.30, P < .01).

CONCLUSIONS

The role of ACEs in health may be related to their associations with executive function and episodic neurocognitive domains essential to cognitive processing and self-regulation. Obesity science should further examine the role of ACEs and neurocognition in obesity prevention, prognosis, and treatment using more rigorous, prospective designs and more diverse samples.

The Clinical Obesity Maintenance Model: A Theoretical Framework for Bariatric Psychology

Ranked highly in its association with serious medical comorbidities, obesity, a rapidly growing epidemic worldwide, poses a significant socio-economic burden. While bariatric procedures offer the most efficacious treatment for weight loss, a subset of patients risk weight recidivism. Due to the heterogeneity of obesity, it is likely that there are phenotypes or sub-groups of patients that require evidence-based psychological support to produce more sustainable outcomes. So far, however, characteristics of patients have not led to a personalized treatment algorithm for bariatric surgery. Maintenance of weight loss following bariatric surgery requires long-term modification of eating behaviors and physical activity. A recent Clinical Obesity Maintenance Model (COMM) proposed a conceptual framework of salient constructs, including the role of habit, behavioral clusters, emotion dysregulation, mood, health literacy, and executive function as interconnected drivers of obesity maintaining behaviors relevant to the field of bariatric psychology. The primary aim of this concise review is to bring together emerging findings from experimental and epidemiological studies relating to the COMM constructs that may inform the assessment and follow up of bariatric surgery. We also aim to explain the phenotypes that need to be understood and screened prior to bariatric surgery to enable better pre-surgery intervention and optimum post-surgery response.

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.

Psychopathology, disordered eating, and impulsivity as predictors of outcomes of bariatric surgery

Outcomes of bariatric surgery, while frequently impressive, are not universal and vary between patients and across surgical procedures. Between 20% and 30% of patients experience suboptimal weight loss or significant weight regain within the first few postoperative years. The reasons for this are not fully understood, but likely involve both physiologic processes, behavioral factors, and psychological characteristics. Evidence suggests that preoperative psychosocial status and functioning can contribute to suboptimal weight losses and/or postoperative psychosocial distress. Much of this work has focused on the presence of recognized psychiatric diagnoses and with particular emphasis on mood disorders as well as binge eating disorder. Several studies have suggested that the presence of preoperative psychopathology is associated with suboptimal weight losses, postoperative complications, and less positive psychosocial outcomes. Contemporary psychological theory suggests that it may be shared features across diagnoses, rather than a discrete diagnosis, that better characterizes psychopathology. Mood and substance use disorders as well as binge eating disorder, share common features of impulsivity, although clinicians and researchers often use complementary, yet different terms, such as emotional dysregulation or disinhibition (i.e., loss of control over eating, as applied to food intake), to describe the phenomenon. Impulse control is a central factor in eating behavior and extreme obesity. It also may contribute to the experience of suboptimal outcomes after bariatric surgery, including smaller than expected weight loss and psychosocial distress. This paper reviews the literature in these areas of research and articulates a direction for future studies of these complex relationships among persons with extreme obesity.

Executive Function, Eating Behavior, and Preoperative Weight Loss in Bariatric Surgery Candidates: An Observational Study

BACKGROUND

Individual differences in executive function may influence eating behavior, weight loss (WL), and WL maintenance in obesity treatment. Executive function, which designates top-down cognitive control processes, has been related to eating behaviors which may impact weight, and has been found to be predictive of WL in both behavioral WL programs and after bariatric surgery. Currently, we lack knowledge on the role of executive function in the period before bariatric surgery. If executive function impacts eating behavior and WL in the preoperative period, it may be a target for clinical attention in this stage.

OBJECTIVES

We aimed to examine the relationship between objective performance-based measures of executive function, eating patterns, and WL in the preoperative period.

METHOD

Baseline data in an ongoing observational longitudinal study of bariatric surgery patients were used. Eighty patients completed neuropsychological testing and self-report questionnaires 4 weeks prior to surgery.

RESULTS

We found that working memory predicted WL before surgery and inhibitory control predicted adherence to dietary recommendations.

CONCLUSION

Our study indicates that executive function may play a role in short-term WL and dietary adherence prior to surgery, suggesting that executive function in the preoperative period deserves an extended research focus.

Precision Medicine in Weight Loss and Healthy Living

Obesity affects 600 million people globally and over one third of the American population. Along with associated comorbidities, including cardiovascular disease, stroke, diabetes, and cancer; the direct and indirect costs of managing obesity are 21% of the total medical costs. These factors shed light on why developing effective and pragmatic strategies to reduce body weight in obese individuals is a major public health concern. An estimated 60-70% of obese Americans attempt to lose weight each year, with only a small minority able to achieve and maintain long term weight loss. To address this issue a precision medicine approach for weight loss has been considered, which places an emphasis on sustainability and real-world application to individualized therapy. In this article we review weight loss interventions in the context of precision medicine and discuss the role of genetic and epigenetic factors, pharmacological interventions, lifestyle interventions, and bariatric surgery on weight loss.

Self-regulation and obesity: the role of executive function and delay discounting in the prediction of weight loss

Obesity rates are rising worldwide. Executive function and delay discounting have been hypothesized to play important roles in the self-regulation of behavior, and may explain variance in weight loss treatment success. First, we compared individuals with obesity (n = 82) to healthy weight controls (n = 71) on behavioral and self-report measures of executive function (working memory, inhibition and shifting) and delay discounting. Secondly, the individuals with obesity took part in a multidisciplinary weight loss program and we examined whether executive function and delay discounting predicted weight change. Individuals with obesity displayed weaker general and food-specific inhibition, and weaker self-reported executive function. Better behavioral working memory and better self-reported inhibition skills in daily life were predictive of greater weight loss. As findings are correlational, future studies should investigate the causal relationship between executive function and weight loss, and test whether intervening on executive function will lead to better prevention and treatment of obesity.

The relationship between executive functioning and weight loss and maintenance in children and parents participating in family-based treatment for childhood obesity

We examined the relationship between executive function and weight loss among children (8-12 years) and parents enrolled in a behavioral weight-loss program. 150 overweight/obese children and their parents participated in a 6-month family-based weight-loss intervention and completed baseline (month 0), post-treatment (month 6) and 18-month follow-up assessments (month 24), which included Digit Span (DS), Stop Signal Task (SST), and Wisconsin Card Sorting Test (WCST). Anthropometrics were additionally measured at mid-treatment (month 3) and 6-month follow-up (month 12). Children with more baseline WCST perseverative errors regained more weight (p = .002) at 18-month follow-up. Change in child BMIz was not associated with change in child executive function (p > .05) or parent executive function (p > .05). Among parents, baseline measure of DS-backward (p < .001) and post-treatment changes in WCST perseverative errors (p < .001) were associated with post-treatment changes in parent BMI. SST was not related to parent or child weight loss. Thus, children's baseline set-shifting was associated with weight regain during follow-up whereas changes in parent set-shifting was associated with changes in parent weight. Future research is needed to examine the relationship between executive function and weight loss and how this translates to intervention success for both overweight/obese children and participating parents.

A Review of Childhood Behavioral Problems and Disorders in the Development of Obesity: Attention Deficit/Hyperactivity Disorder, Autism Spectrum Disorder, and Beyond

PURPOSE OF REVIEW

Given the high rates of pediatric and adult obesity, it is imperative to identify early risk factors that might contribute to excess weight gain. This review aims to investigate the relationship between childhood behavioral problems with the development and persistence of obesity. Specifically, this review highlights the association of obesity with (1) neurocognitive constructs, such as executive functioning and inhibition/impulsivity, and (2) disorders commonly diagnosed in childhood, including attention deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD).

RECENT FINDINGS

Consistent evidence supports a relationship between childhood behavioral problems, executive functioning, inhibition/impulsivity, ADHD, and ASD with obesity across the lifespan. Longitudinal studies suggest behavior problems, neurocognitive functioning deficits, and ADHD symptoms in childhood predict weight gain over time. Identifying risk factors in childhood that promote obesity may help develop targeted intervention and prevention programs. Additional research should elucidate mechanisms that account for these relationships.

Cognitive effects of a 30-min aerobic exercise bout on adults with overweight/obesity and type 2 diabetes

Background

Several studies document reliable brain health benefits of acute exercise bouts. However, no prior studies have explored such effects among those living with co‐morbid overweight/obesity and type 2 diabetes (T2DM), both of which are conditions associated with cognitive performance decrements.

Purpose

To examine the impact of a 30‐min bout of moderate‐intensity aerobic exercise on executive function among adults with overweight/obesity and T2DM, employing a widely used experimental paradigm.

Methods

Thirty adults with overweight/obesity and T2DM were randomly assigned to moderate (30% maximal heart rate reserve) and minimal (r.p.m. 30–50; work load 5) intensity aerobic exercise. Pre‐exercise to post‐exercise changes in Stroop interference and Go/No‐Go scores were compared across conditions.

Results

Primary analyses revealed no overall effect of exercise condition on changes in Stroop or Go/No‐Go performance. Post‐hoc moderation analyses indicated that Stroop interference scores were reduced, following moderate exercise among female participants and among those who were more physically active.

Conclusion

The current study revealed no reliable benefit of acute aerobic exercise for overweight and obese individuals living with T2DM overall. There may be limited benefits for women and more and active subgroups, but the precise nature of such benefits remains unclear.

Executive functions predict weight loss in a medically supervised weight loss programme

Background

Deficits in executive functions are related to poorer weight loss after bariatric surgery; however, less is known about the role that these deficits may play during participation in nonsurgical weight loss programmes. This study examined associations between objectively measured executive functions and weight loss during participation in a medically supervised weight loss programme.

Methods

Twenty‐three adult patients (age 50.4 ± 15.1, BMI 44.2 ± 8.8, 68% female, 92% White) enrolled in a medically supervised weight loss programme, involving prescription of a very low calorie diet and strategies to change eating and activity behaviours, underwent comprehensive computerized testing of executive functions at baseline. Weight was obtained at baseline and 8 weeks. Demographic and clinical information were obtained through medical chart review.

Results

Participants lost an average of 9.8 ± 3.4% of their initial body weight at 8 weeks. Fewer correct responses on a set‐shifting task and faster reaction time on a response inhibition task were associated with lower weight loss percentage at 8 weeks after adjusting for age, education and depressive symptoms. There were no associations between performance on tests of working memory or planning and weight loss.

Conclusions

This study shows that worse performance on a set‐shifting task (indicative of poorer cognitive flexibility) and faster reaction times on a response inhibition test (indicative of higher impulsivity) are associated with lower weight loss among participants in a medically supervised weight loss programme. Pre‐treatment assessment of executive functions may be useful in identifying individuals who may be at risk for suboptimal treatment outcomes. Future research is needed to replicate these findings in larger samples and identify underlying mechanisms.