Allostatic load and executive functions in overweight adults

Emerging Theories of Allostatic-Interoceptive Overload in Neurodegeneration

Recent integrative multilevel models offer novel insights into the etiology and course of neurodegenerative conditions. The predictive coding of allostatic-interoception theory posits that the brain adapts to environmental demands by modulating internal bodily signals through the allostatic-interoceptive system. Specifically, a domain-general allostatic-interoceptive network exerts adaptive physiological control by fine-tuning initial top-down predictions and bottom-up peripheral signaling. In this context, adequate adaptation implies the minimization of prediction errors thereby optimizing energy expenditure. Abnormalities in top-down interoceptive predictions or peripheral signaling can trigger allostatic overload states, ultimately leading to dysregulated interoceptive and bodily systems (endocrine, immunological, circulatory, etc.). In this context, environmental stress, social determinants of health, and harmful exposomes (i.e., the cumulative life-course exposition to different environmental stressors) may interact with physiological and genetic factors, dysregulating allostatic interoception and precipitating neurodegenerative processes. We review the allostatic-interoceptive overload framework across different neurodegenerative diseases, particularly in the behavioral variant frontotemporal dementia (bvFTD). We describe how concepts of allostasis and interoception could be integrated with principles of predictive coding to explain how the brain optimizes adaptive responses, while maintaining physiological stability through feedback loops with multiple organismic systems. Then, we introduce the model of allostatic-interoceptive overload of bvFTD and discuss its implications for the understanding of pathophysiological and neurocognitive abnormalities in multiple neurodegenerative conditions.

Evidence for an association between allostatic load and multisensory integration in middle-aged and older adults

Multisensory integration, the ability of the brain to integrate information from different sensory modalities, is critical for responding to environmental stimuli. While older adults show changes in multisensory integration with age, the impact of allostatic load (AL) (i.e., the effect of exposure to chronic stress, which can accelerate ageing) on multisensory perception remains understudied. We explored the relationship between multisensory integration and AL in 1,358 adults aged 50+ from The Irish Longitudinal Study on Ageing by performing a Sound Induced Flash Illusion (SIFI) task at multiple audio-visual temporal asynchronies. The AL score was created using a battery of biomarkers representing the activity of four major physiological systems: immunological, cardiovascular, metabolic, and renal. The number of biomarkers for which a participant was categorised in the highest risk quartile using sex-specific cutoffs was used to produce an overall AL score. We accounted for medication use when calculating our AL score. We analysed the accuracy of illusion trials on a SIFI task using generalised logistic mixed effects regression models adjusted for a number of covariates. Observation of cross-sectional and longitudinal results revealed that lower accuracy in integration (i.e., higher SIFI susceptibility with larger temporal asynchronies) was associated with higher AL. This confirmed the distinct patterns of multisensory integration in ageing.

Inflammation and lipid metabolism as potential biomarkers of memory impairment across type 2 diabetes mellitus and severe mental disorders

INTRODUCTION

Neurocognitive impairment is a transdiagnostic feature across several psychiatric and cardiometabolic conditions. The relationship between inflammatory and lipid metabolism biomarkers and memory performance is not fully understood. This study aimed to identify peripheral biomarkers suitable to signal memory decline from a transdiagnostic and longitudinal perspective.

METHODS

Peripheral blood biomarkers of inflammation, oxidative stress and lipid metabolism were assessed twice over a 1-year period in 165 individuals, including 30 with schizophrenia (SZ), 42 with bipolar disorder (BD), 35 with major depressive disorder (MDD), 30 with type 2 diabetes mellitus (T2DM), and 28 healthy controls (HCs). Participants were stratified by memory performance quartiles, taking as a reference their global memory score (GMS) at baseline, into categories of high memory (H; n = 40), medium to high memory (MH; n = 43), medium to low memory (ML; n = 38) and low memory (L; n = 44). Exploratory and confirmatory factorial analysis, mixed one-way analysis of covariance and discriminatory analyses were performed.

RESULTS

L group was significantly associated with higher levels of tumor necrosis factor-alpha (TNF-α) and lower levels of apolipoprotein A1 (Apo-A1) compared to those from the MH and H groups (p < 0.05; η2p = 0.06-0.09), with small to moderate effect sizes. Moreover, the combination of interleukin-6 (IL-6), TNF-α, c-reactive protein (CRP), Apo-A1 and Apo-B compounded the transdiagnostic model that best discriminated between groups with different degrees of memory impairment (χ2 = 11.9-49.3, p < 0.05-0.0001).

CONCLUSIONS

Inflammation and lipid metabolism seem to be associated with memory across T2DM and severe mental illnesses (SMI). A panel of biomarkers may be a useful approach to identify individuals at greater risk of neurocognitive impairment. These findings may have a potential translational utility for early intervention and advance precision medicine in these disorders.

The influence of stress on the neural underpinnings of disinhibited eating: a systematic review and future directions for research

Disinhibited eating involves overconsumption and loss of control over food intake, and underpins many health conditions, including obesity and binge-eating related disorders. Stress has been implicated in the development and maintenance of disinhibited eating behaviours, but the mechanisms underlying this relationship are unclear. In this systematic review, we examined how the impact of stress on the neurobiological substrates of food-related reward sensitivity, interoception and cognitive control explains its role in disinhibited eating behaviours. We synthesised the findings of functional magnetic resonance imaging studies including acute and/or chronic stress exposures in participants with disinhibited eating. A systematic search of existing literature conducted in alignment with the PRISMA guidelines identified seven studies investigating neural impacts of stress in people with disinhibited eating. Five studies used food-cue reactivity tasks, one study used a social evaluation task, and one used an instrumental learning task to probe reward, interoception and control circuitry. Acute stress was associated with deactivation of regions in the prefrontal cortex implicated in cognitive control and the hippocampus. However, there were mixed findings regarding differences in reward-related circuitry. In the study using a social task, acute stress associated with deactivation of prefrontal cognitive control regions in response to negative social evaluation. In contrast, chronic stress was associated with both deactivation of reward and prefrontal regions when viewing palatable food-cues. Given the small number of identified publications and notable heterogeneity in study designs, we propose several recommendations to strengthen future research in this emerging field.

Longitudinal association of allostatic load with depressive symptoms among urban adults: Healthy Aging in Neighborhoods of Diversity across the Life Span study

BACKGROUND

Evidence suggests that lifetime exposure to stressful life events and chronic stressors may be linked to geriatric depression. Allostatic load (AL) is considered a mediator of the stress-health relationship and has been linked to psychosocial factors reflecting health disparities. The purpose of this study was to examine the longitudinal associations of AL with depressive symptoms scores among urban adults, before and after stratifying by sex and race.

METHODS

Secondary analyses were performed using Visit 1 (2004-2009), Visit 2 (2009-2013) and Visit 3 (2013-2017) data collected on 2298 Healthy Aging in Neighborhoods of Diversity across the Life Span study participants (baseline age: 30-64 y). AL at Visit 1 (ALv1) and z-transformed probability of higher AL trajectory (ALtraj) between Visits 1 and 3 were calculated using cardiovascular, metabolic and inflammatory risk indicators. The 20-item Center for Epidemiologic Studies Depression (CES-D) scale was used to calculate total and domain-specific depressive symptoms scores. Mixed-effects linear models controlled for socio-demographic, lifestyle and health characteristics.

RESULTS

In fully adjusted models, a positive cross-sectional relationship was observed between ALv1 and "somatic complaints" depressive symptoms (β = 0.21, P = 0.006) score at Visit 1, whereas ALtraj was associated with increasing depressive symptoms score (β = 0.086, P = 0.003) between Visits 1 and 3. An inverse relationship was observed between ALtraj and "positive affect" depressive symptoms score at Visit 1 among women (β = -0.31, P < 0.0001) and White adults (β = -0.32, P = 0.004). Among women, ALtraj was also positively related to change in "somatic complaints" depressive symptoms score between Visits 1 and 3 (β = 0.043, P = 0.020).

CONCLUSIONS

Among urban adults, AL may be associated with "somatic complaints" depressive symptoms at baseline. Higher AL trajectories may predict increasing depressive symptoms (overall) and increasing "somatic complaints" depressive symptoms (among women). A higher AL trajectory may be associated with lower "positive affect" depressive symptoms at baseline among women and White adults only.

Allostatic Load and Cognitive Function Among Urban Adults in the Healthy Aging in Neighborhoods of Diversity across the Life Span Study

BACKGROUND

Cross-sectional studies have linked cognition to allostatic load (AL) which reflects multisystem dysregulation from life course exposure to stressors.

OBJECTIVE

To examine baseline and changes in AL and their relationships with 11 cognitive function test scores, while exploring health disparities according to sex and race.

METHODS

Longitudinal [Visit 1 (2004-2009) and Visit 2 (2009-2013)] data were analyzed from 2,223 Healthy Aging in Neighborhoods of Diversity across the Life Span participants. We calculated AL total score using cardiovascular, metabolic, and inflammatory risk indicators, and applied group-based trajectory modeling to define AL change.

RESULTS

Overall and stratum-specific relationships were evaluated using mixed-effects linear regression models that controlled for socio-demographic, lifestyle, and health characteristics. Baseline AL was significantly associated with higher log-transformed Part A Trail Making Test score [Loge (TRAILS A)] (β= 0.020, p = 0.004) and increasing AL was associated with higher Benton Visual Retention Test score [BVRT] (β= 0.35, p = 0.002) at baseline, in models that controlled for age, sex, race, poverty status, education, literacy, smoking, drug use, the 2010 healthy eating index and body mass index. Baseline AL and AL change were not related to change in cognitive function between visits. There were no statistically significant interaction effects by sex or race in fully-adjusted models.

CONCLUSION

At baseline, AL was associated with worse attention or executive functioning. Increasing AL was associated with worse non-verbal memory or visuo-constructional abilities at baseline. AL was not related to change in cognitive function over time, and relationships did not vary by sex or race.

Allostatic Load Measurement: A Systematic Review of Reviews, Database Inventory, and Considerations for Neighborhood Research

BACKGROUND

Neighborhoods are critical to understanding how environments influence health outcomes. Prolonged environmental stressors, such as a lack of green spaces and neighborhood socioeconomic disadvantage, have been associated with higher allostatic load levels. Since allostatic load levels experienced earlier in life have stronger associations with mortality risk, neighborhoods may be uniquely suited to monitor and mitigate the impacts of environmental stressors. Researchers often study allostatic load in neighborhoods by utilizing administrative boundaries within publicly accessible databases as proxies for neighborhoods.

METHODS

This systematic review of reviews aims to identify commonly used biomarkers in the measurement of allostatic load, compare measurement approaches, inventory databases to study allostatic load, and spotlight considerations referenced in the literature where allostatic load is studied in neighborhoods. The review was conducted using the search term "allostatic load" in the MEDLINE, CINAHL, and PsychINFO databases. The search results were filtered to include reviews.

RESULTS

The search returned 499 articles after deduplication. Overall, 18 synthesis reviews met the inclusion criteria and were retained for extraction. The synthesis reviews analyzed represented 238 studies published from 1995 to 2020. The original ten biomarkers were most often used to measure allostatic load. More recently, body mass index and C-reactive protein have additionally been frequently used to measure allostatic load burden.

CONCLUSIONS

The scientific contributions of this study are that we have identified a clear gap in geographic considerations when studying allostatic load. The implication of this study is that we have highlighted geographic concepts when conducting neighborhood-level research using administrative databases as a neighborhood proxy and outlined emerging future trends that can enable future study of allostatic load in the neighborhood context.

Depression interacts with allostatic load to predict cognitive decline in middle age

BACKGROUND

Allostatic load (AL) indicates the cumulative impact of stress on homeostatic mechanisms. Depression and AL have been associated with cognitive deficits, but it is unclear if they do so independently.

METHODS

Using data from middle-aged participants in the observational longitudinal Midlife in the United States (MIDUS) study (n = 704, 57.5 % female, 63.8 ± 10.6 years old in 2014), we assessed whether the effect of prior depression (Composite International Diagnostic Interview Short-Form in 1995) on cognitive decline between 2004 and 2013 (composite Z-scores derived from the Brief Test of Adult Cognition by Telephone and the Stop & Go Switch Task) was moderated by AL Z-scores in 2004 (calculated from biomarkers in blood, urine, and electrocardiography).

RESULTS

A significant depression × AL interaction predicted a decline in a composite cognitive score (β = -0.066, SE=0.029, p = 0.024) and executive function (β = -0.068, SE=0.025, p = 0.007). Depression predicted a decline in composite cognition among those with AL Z-scores above - 0.055. AL subdomains of inflammation and lipid metabolism showed evidence of moderation.

CONCLUSION

Middle-aged adults with depression who had higher allostatic load were at greater risk of cognitive decline. Future studies should evaluate whether the interaction predicts incident dementia, and whether interventions targeting depression or elevated AL in people who have both can attenuate cognitive decline.

Memory function performance in individuals classified as overweight, obese, and normal weight

Evidence accumulated to date about the relationship between cognitive impairments and adults who are overweight and obese suggests that excess weight has a great impact on memory function. Nevertheless, most of the literature has focused only on studying the influences on working memory and episodic memory. This study aimed to examine the potential associations of clinical and anthropometric measures [body mass index (BMI), WHR, body fat, visceral fat, muscle mass, and hypertension] with six memory domains, including contextual memory, short-term visual memory, short-term memory, non-verbal memory, short-term phonological memory, and working memory, in a sample of 124 individuals classified as overweight (n = 33), obese (n = 53), and normal weight (n = 38). The results obtained showed that, after controlling for employment situations, people classified as obese had poorer short-term phonological memory and working memory than those with normal weights. Bivariate correlations showed that measures of weight, BMI, waist-hip ratio index, body fat, and visceral fat were inversely associated with memory function. However, muscle mass was not a significant predictor of memory function. Higher systolic blood pressure was also associated with worse memory function. The study provides evidence of the importance of adiposity in health and memory function.

A predictive coding framework of allostatic-interoceptive overload in frontotemporal dementia

Recent allostatic-interoceptive explanations using predictive coding models propose that efficient regulation of the body's internal milieu is necessary to correctly anticipate environmental needs. We review this framework applied to understanding behavioral variant frontotemporal dementia (bvFTD) considering both allostatic overload and interoceptive deficits. First, we show how this framework could explain divergent deficits in bvFTD (cognitive impairments, behavioral maladjustment, brain atrophy, fronto-insular-temporal network atypicality, aberrant interoceptive electrophysiological activity, and autonomic disbalance). We develop a set of theory-driven predictions based on levels of allostatic interoception associated with bvFTD phenomenology and related physiopathological mechanisms. This approach may help further understand the disparate behavioral and physiopathological dysregulations of bvFTD, suggesting targeted interventions and strengthening clinical models of neurological and psychiatric disorders.

Allostatic-Interoceptive Overload in Frontotemporal Dementia

BACKGROUND

The predictive coding theory of allostatic-interoceptive load states that brain networks mediating autonomic regulation and interoceptive-exteroceptive balance regulate the internal milieu to anticipate future needs and environmental demands. These functions seem to be distinctly compromised in behavioral variant frontotemporal dementia (bvFTD), including alterations of the allostatic-interoceptive network (AIN). Here, we hypothesize that bvFTD is typified by an allostatic-interoceptive overload.

METHODS

We assessed resting-state heartbeat evoked potential (rsHEP) modulation as well as its behavioral and multimodal neuroimaging correlates in patients with bvFTD relative to healthy control subjects and patients with Alzheimer's disease (N = 94). We measured 1) resting-state electroencephalography (to assess the rsHEP, prompted by visceral inputs and modulated by internal body sensing), 2) associations between rsHEP and its neural generators (source location), 3) cognitive disturbances (cognitive state, executive functions, facial emotion recognition), 4) brain atrophy, and 5) resting-state functional magnetic resonance imaging functional connectivity (AIN vs. control networks).

RESULTS

Relative to healthy control subjects and patients with Alzheimer's disease, patients with bvFTD presented more negative rsHEP amplitudes with sources in critical hubs of the AIN (insula, amygdala, somatosensory cortex, hippocampus, anterior cingulate cortex). This exacerbated rsHEP modulation selectively predicted the patients' cognitive profile (including cognitive decline, executive dysfunction, and emotional impairments). In addition, increased rsHEP modulation in bvFTD was associated with decreased brain volume and connectivity of the AIN. Machine learning results confirmed AIN specificity in predicting the bvFTD group.

CONCLUSIONS

Altogether, these results suggest that bvFTD may be characterized by an allostatic-interoceptive overload manifested in ongoing electrophysiological markers, brain atrophy, functional networks, and cognition.

Limitations of the protective measure theory in explaining the role of childhood sexual abuse in eating disorders, addictions, and obesity: an updated model with emphasis on biological embedding

In addition to its immediate negative consequences, childhood sexual abuse is associated with lifelong deleterious mental and physical health outcomes. This review employs a biopsychosocial perspective to better understand pathways from childhood sexual abuse to eating disorders, food and drug addictions, and obesity across the life course. Guided by an updated conceptual model, this review delineates how the biological embedding of childhood sexual abuse triggers a cascade of interrelated conditions that often result in failed attempts at weight suppression and eventually obesity. Such biological embedding involves pathways such as inflammation, allostatic load, reward sensitivity, activation of the hypothalamic-pituitary-adrenal axis, epigenetics, and structural and functional changes in the brain. These pathways are in turn theorized to lead to food addiction, substance use disorder, and eating disorders-each with potential pathways toward obesity over time. Predisposing factors to childhood sexual abuse including gender, culture, and age are discussed. This model calls into question the longstanding "protective measure" theory that purports individuals exposed to sexual abuse will deliberately or subconsciously gain weight in attempt to prevent future victimization. A more comprehensive understanding of the mechanisms by which childhood sexual abuse becomes biologically embedded may help clinicians and survivors normalize and/or address disordered eating and weight-related outcomes, as well as identify intervention strategies.Level of evidence: Level V: opinions of respected authorities, based on descriptive studies, narrative reviews, clinical experience, or reports of expert committees.

Allostatic Load and Its Impact on Health: A Systematic Review

INTRODUCTION

Allostatic load refers to the cumulative burden of chronic stress and life events. It involves the interaction of different physiological systems at varying degrees of activity. When environmental challenges exceed the individual ability to cope, then allostatic overload ensues. Allostatic load is identified by the use of biomarkers and clinical criteria.

OBJECTIVE

To summarize the current knowledge on allostatic load and overload and its clinical implications based on a systematic review of the literature.

METHODS

PubMed, PsycINFO, Web of Science, and the Cochrane Library were searched from inception to December 2019. A manual search of the literature was also performed, and reference lists of the retrieved articles were examined.We considered only studies in which allostatic load or overload were adequately described and assessed in either clinical or non-clinical adult populations.

RESULTS

A total of 267 original investigations were included. They encompassed general population studies, as well as clinical studies on consequences of allostatic load/overload on both physical and mental health across a variety of settings.

CONCLUSIONS

The findings indicate that allostatic load and overload are associated with poorer health outcomes. Assessment of allostatic load provides support to the understanding of psychosocial determinants of health and lifestyle medicine. An integrated approach that includes both biological markers and clinimetric criteria is recommended.

Effectiveness of combined exercise in people with type 2 diabetes and concurrent overweight/obesity: a systematic review and meta-analysis

OBJECTIVE

To synthesise the available scientific evidence on the effects of combined exercise on glycaemic control, weight loss, insulin sensitivity, blood pressure and serum lipids among patients with type 2 diabetes (T2D) and concurrent overweight/obesity.

DESIGN AND SAMPLE

PubMed, EMBASE, Web of Science, the Cochrane library, WANFANG, CNKI, SinoMed, OpenGrey and ClinicalTrials.gov were searched from inception through April 2020 to identify randomised controlled trials (RCTs) that reported the effects of combined exercise in individuals with T2D and concurrent overweight/obesity.

METHODS

Quality assessment was performed using the Cochrane Collaboration's risk of bias tool. The mean difference (MD) with its corresponding 95% CI was used to estimate the effect size. Meta-analysis was performed using Review Manager V.5.3.

RESULTS

A total of 10 RCTs with 978 participants were included in the meta-analysis. Pooled results demonstrated that combined exercise significantly reduced haemoglobin A1c (MD=-0.16%, 95% CI: -0.28 to -0.05, p=0.006); body mass index (MD=-0.98 kg/m², 95% CI: -1.41 to -0.56, p<0.001); homeostasis model assessment of insulin resistance (MD=-1.19, 95% CI: -1.93 to -0.46, p=0.001); serum insulin (MD=-2.18 μIU/mL, 95% CI: -2.99 to -1.37, p<0.001) and diastolic blood pressure (MD=-3.24 mm Hg, 95% CI: -5.32 to -1.16, p=0.002).

CONCLUSIONS

Combined exercise exerted significant effects in improving glycaemic control, influencing weight loss and enhancing insulin sensitivity among patients with T2D and concurrent overweight/obesity.

Stress-induced aberrations in sensory processing predict worse cognitive outcomes in healthy aging adults

It is well recognized that not all individuals age equivalently, with functional dependence attributable, at least in part, to stress accumulated across the lifespan. Amongst these dependencies are age-related declines in cognitive function, which may be the result of impaired inhibitory processing (e.g., sensory gating). Herein, we examined the unique roles of life and biological stress on somatosensory gating dynamics in 74 adults (22-72 years old). Participants completed a sensory gating paired-pulse electrical stimulation paradigm of the right median nerve during magnetoencephalography (MEG) and data were subjected to advanced oscillatory and time-domain analysis methods. We observed separable mechanisms by which increasing levels of life and biological stress predicted higher oscillatory gating ratios, indicative of age-related impairments in inhibitory function. Specifically, elevations in life stress significantly modulated the neural response to the first stimulation in the pair, while elevations in biological stress significantly modulated the neural response to the second stimulation in the pair. In contrast, neither elevations in life nor biological stress significantly predicted the gating of time-domain neural activity in the somatosensory cortex. Finally, our study is the first to link stress-induced decline in sensory gating to cognitive dysfunction, suggesting that gating paradigms may hold promise for detecting discrepant functional trajectories in age-related pathologies in the future.

Restrained Eating Is Associated with Lower Cortical Thickness in the Inferior Frontal Gyrus in Adolescents

Some eating patterns, such as restrained eating and uncontrolled eating, are risk factors for eating disorders. However, it is not yet clear whether they are associated with neurocognitive differences. In the current study, we analyzed whether eating patterns can be used to classify participants into meaningful clusters, and we examined whether there are neurocognitive differences between the clusters. Adolescents (n = 108; 12 to 17 years old) and adults (n = 175, 18 to 40 years old) completed the Three Factor Eating Questionnaire, which was used to classify participants according to their eating profile using k means clustering. Participants also completed personality questionnaires and a neuropsychological examination. A subsample of participants underwent a brain MRI acquisition. In both samples, we obtained a cluster characterized by high uncontrolled eating patterns, a cluster with high scores in restrictive eating, and a cluster with low scores in problematic eating behaviors. The clusters were equivalent with regards to personality and performance in executive functions. In adolescents, the cluster with high restrictive eating showed lower cortical thickness in the inferior frontal gyrus compared to the other two clusters. We hypothesize that this difference in cortical thickness represents an adaptive neural mechanism that facilitates inhibition processes.

The Role of BMI, Body Fat Mass and Visceral Fat in Executive Function in Individuals with Overweight and Obesity

Evidence accumulated to date suggests that excess weight in the adult population is associated with a wide range of impairments in executive function. However, most studies have only examined the influence of body mass index (BMI) on the cognitive function of individuals with overweight and obesity. This study examined the potential associations of markers of adiposity (BMI, body fat, and visceral fat) with five domains of executive function including cognitive flexibility, inhibition, monitoring, planning, and working memory in a sample of 87 adult with overweight (n = 34) and obesity (n = 53). The results show that obese people had poorer working memory than those with overweight. After controlling for educational levels and physical activity, the results suggest that neither the waist-hip index not visceral fat were associated with cognitive function. In overweight, body fat was negatively associated with executive components of inhibition (p = 0.05) and monitoring (p = 0.02). In the obesity subgroup, body fat was negatively associated with inhibition (0.02) and working memory (0.04). The results provide evidence of the importance of adiposity for cognitive function. The implications for understanding the influence of markers of adiposity in adults with overweight and obesity are discussed.

Executive Function Training in Childhood Obesity: Food Choice, Quality of Life, and Brain Connectivity (TOuCH): A Randomized Control Trial Protocol

Background: Individuals with obesity are known to present cognitive deficits, especially in executive functions. Executive functions play an important role in health and success throughout the whole life and have been related to food decision-making and to the ability to maintain energy balance. It is possible to improve executive functions through targeted training. This would involve brain plasticity changes that could be studied through connectivity MRI. The general hypothesis of this study is that executive functions training in children with obesity can improve food choices and produce cognitive and neuroimaging changes (structural and functional connectivity), as well as improve emotional state and quality of life. Methods: Randomized controlled double-blind trial with 12-month follow-up. Thirty children with obesity will be randomly allocated into "executive training" (Cognifit with adaptive difficulty + Cogmed) or "control task" group (Cognifit without adaptive difficulty). Both groups will attend 30-45 min of individual gamified training (Cogmed and/or Cognifit systems) by iPad, five times per week during 6 weeks. Cogmed and Cognifit software are commercially available from Pearson and Cognifit, respectively. Participants will receive an iPad with both apps installed for a 6-week use. Participants will also receive counseling diet information via presentations sent to the iPad and will wear a Fitbit Flex 2 tracker to monitor daily activity and sleep patterns. Main outcomes will be cognitive, emotional, food decision, and quality-of-life measures, as well as neuroimaging measures. Participants are evaluated at baseline (T0), after treatment (T1), and 12 months since baseline (T2). Discussion: Longitudinal study with active control group and 3 time points: baseline, immediately after treatment, and 1 year after baseline. Threefold treatment: executive function training, psychoeducation, and feedback on activity/sleep tracking. We will evaluate the transfer effects of the intervention, including emotional and functional outcomes, as well as the effects on neural plasticity by connectivity MRI. Trial registration: This project has been registered in ClinicalTrials.gov (trial registration number NCT03615274), August 3, 2018.

Food Addiction and Psychosocial Adversity: Biological Embedding, Contextual Factors, and Public Health Implications

The role of stress, trauma, and adversity particularly early in life has been identified as a contributing factor in both drug and food addictions. While links between traumatic stress and substance use disorders are well documented, the pathways to food addiction and obesity are less established. This review focuses on psychosocial and neurobiological factors that may increase risk for addiction-like behaviors and ultimately increase BMI over the lifespan. Early childhood and adolescent adversity can induce long-lasting alterations in the glucocorticoid and dopamine systems that lead to increased addiction vulnerability later in life. Allostatic load, the hypothalamic-pituitary-adrenal axis, and emerging data on epigenetics in the context of biological embedding are highlighted. A conceptual model for food addiction is proposed, which integrates data on the biological embedding of adversity as well as upstream psychological, social, and environmental factors. Dietary restraint as a feature of disordered eating is discussed as an important contextual factor related to food addiction. Discussion of various public health and policy considerations are based on the concept that improved knowledge of biopsychosocial mechanisms contributing to food addiction may decrease stigma associated with obesity and disordered eating behavior.

The association between allostatic load and cognitive function: A systematic and meta-analytic review

Previous research suggests that high allostatic load (AL), a biological indicator of physiological dysregulation due to chronic stress, is associated with poor cognitive functioning. To date, no studies have systematically reviewed the literature to evaluate the strength and consistency of this relationship. The objective of this study was to conduct a systematic and meta-analytic review of studies that have investigated the association between AL and performance on standardized cognitive tests among adults aged 18 years and older. A total of 18 studies were retained for review. Meta-analyses revealed a significant cross-sectional association between higher AL and poor global cognition (r = -0.08, p <  0.001) and executive function (r = -0.07, p =  0.02), but not memory (r = -0.07, p =  0.10). Due to variation in statistical methods used, longitudinal meta-analyses were not performed. Qualitative review of the literature suggests that AL algorithm, physiological systems and individual biomarkers included in the AL index, and sample age may be key moderators of the AL-cognition relationship. Although the magnitude of reported associations is small, findings support AL as a robust indicator of cognitive function among adults. Study limitations and future directions are discussed.

A scoping review of interventions targeting allostatic load

Allostatic load (AL) is the manifestation of cumulative responses to chronic stress exposure. Numerous studies have shown the importance of AL in understanding disease risks. Yet little is known about existing interventions that target AL specifically. We aimed to address this gap by identifying interventions targeting AL and determining the success of these interventions in improving biological functioning. We searched five electronic databases using variations of two concepts: AL and programs or interventions. We included original research reports that focused on AL as an outcome. We excluded work that focused on a single indicator, not written in English or did not implement an intervention. The Template for Intervention Description and Replication checklist guided our intervention critique and synthesis. Six articles were included, with sample size across the interventions ranging between 2 and 733. Despite inconsistencies in the selection of AL indicators and scoring of AL, all four body systems were represented in all the studies. Four interventions showed significant improvement in Al (as indicated by a decrease in AL score) as early as 7 weeks. More interventions targeting Al are needed. The reduction in AL scores among four of the six interventions suggests that Al could be a biological outcome measure that is sensitive to change in response to interventions. This has significant clinical and research implications. Future studies are needed to examine whether AL serves as a mediator in the effects of the intervention on improving clinical manifestations of diseases.

The association between obesity and lower working memory is mediated by inflammation: Findings from a nationally representative dataset of U.S. adults

Obesity is often accompanied by lower working memory (e.g., a lower ability to keep goal-relevant information in mind) relative to healthy weight individuals. Understanding this relative working memory impairment has important clinical implications, as working memory is thought to facilitate adherence to weight management programs. Theoretical models of obesity, self-regulation, and inflammation suggest that inflammation plays a role in obesity-related working memory impairments, but to date no study has tested this prediction. Therefore, the current study examined whether inflammation statistically mediated the relationship between obesity and working memory in a nationally representative dataset of U.S. adults from Wave IV of The National Longitudinal Study of Adolescent to Adult Health (N = 11,546, age range 25-34). Inflammation was quantified via C-reactive protein (CRP) level, and working memory was assessed using a modified digit span backward task. As expected, cross-sectional analyses showed that a body mass index (BMI) indicative of obesity-as well as greater BMI when BMI was analyzed continuously-and greater CRP were each related to lower working memory. Critically, we found that CRP levels statistically mediated the relationships between obesity/greater BMI and working memory, with CRP accounting for 44.1% of the variance explained in working memory by BMI. Moreover, these findings held both with and without controlling for relevant covariates, including demographic characteristics (e.g., age), socioeconomic status, and behavioral factors (e.g., smoking). Our results therefore point to inflammation as playing an important role in the relationship between obesity and working memory, and suggest that interventions aimed at reducing inflammation may help lessen the cognitive burden of obesity.