Systematically lower structural brain connectivity in individuals with elevated food addiction symptoms

Ultra-Processed Foods and Mental Health: Where Do Eating Disorders Fit into the Puzzle?

Ultra-processed foods (UPFs) like pastries, packaged snacks, fast foods, and sweetened beverages have become dominant in the modern food supply and are strongly associated with numerous public health concerns. While the physical health consequences of UPF intake have been well documented (e.g., increased risks of cardiometabolic conditions), less empirical discussion has emphasized the mental health consequences of chronic UPF consumption. Notably, the unique characteristics of UPFs (e.g., artificially high levels of reinforcing ingredients) influence biological processes (e.g., dopamine signaling) in a manner that may contribute to poorer psychological functioning for some individuals. Importantly, gold-standard behavioral lifestyle interventions and treatments specifically for disordered eating do not acknowledge the direct role that UPFs may play in sensitizing reward-related neural functioning, disrupting metabolic responses, and motivating subsequent UPF cravings and intake. The lack of consideration for the influences of UPFs on mental health is particularly problematic given the growing scientific support for the addictive properties of these foods and the utility of ultra-processed food addiction (UPFA) as a novel clinical phenotype endorsed by 14-20% of individuals across international samples. The overarching aim of the present review is to summarize the science of how UPFs may affect mental health, emphasizing contributing biological mechanisms. Specifically, the authors will (1) describe how corporate-sponsored research and financial agendas have contributed to contention and debate about the role of UPFs in health; (2) define UPFs and their nutritional characteristics; (3) review observed associations between UPF intake and mental health conditions, especially with depression; (4) outline the evidence for UPFA; and (5) describe nuanced treatment considerations for comorbid UPFA and eating disorders.

From "online brains" to "online lives": understanding the individualized impacts of Internet use across psychological, cognitive and social dimensions

In response to the mass adoption and extensive usage of Internet-enabled devices across the world, a major review published in this journal in 2019 examined the impact of Internet on human cognition, discussing the concepts and ideas behind the "online brain". Since then, the online world has become further entwined with the fabric of society, and the extent to which we use such technologies has continued to grow. Furthermore, the research evidence on the ways in which Internet usage affects the human mind has advanced considerably. In this paper, we sought to draw upon the latest data from large-scale epidemiological studies and systematic reviews, along with randomized controlled trials and qualitative research recently emerging on this topic, in order to now provide a multi-dimensional overview of the impacts of Internet usage across psychological, cognitive and societal outcomes. Within this, we detail the empirical evidence on how effects differ according to various factors such as age, gender, and usage types. We also draw from new research examining more experiential aspects of individuals' online lives, to understand how the specifics of their interactions with the Internet, and the impact on their lifestyle, determine the benefits or drawbacks of online time. Additionally, we explore how the nascent but intriguing areas of culturomics, artificial intelligence, virtual reality, and augmented reality are changing our understanding of how the Internet can interact with brain and behavior. Overall, the importance of taking an individualized and multi-dimensional approach to how the Internet affects mental health, cognition and social functioning is clear. Furthermore, we emphasize the need for guidelines, policies and initiatives around Internet usage to make full use of the evidence available from neuroscientific, behavioral and societal levels of research presented herein.

Relationship between functional connectivity and weight-gain risk of antipsychotics in schizophrenia

BACKGROUND

The mechanisms by which antipsychotic medications (APs) contribute to obesity in schizophrenia are not well understood. Because AP effects on functional brain connectivity may contribute to weight effects, the current study investigated how AP-associated weight-gain risk relates to functional connectivity in schizophrenia.

METHODS

Fifty-five individuals with schizophrenia (final N = 54) were divided into groups based on previously reported AP weight-gain risk (no APs/low risk [N = 19]; moderate risk [N = 17]; high risk [N = 18]). Resting-state functional magnetic resonance imaging (fMRI) was completed after an overnight fast ("fasted") and post-meal ("fed"). Correlations between AP weight-gain risk and functional connectivity were assessed at the whole-brain level and in reward- and eating-related brain regions (anterior insula, caudate, nucleus accumbens).

RESULTS

When fasted, greater AP weight-gain risk was associated with increased connectivity between thalamus and sensorimotor cortex (pFDR = 0.021). When fed, greater AP weight-gain risk was associated with increased connectivity between left caudate and left precentral/postcentral gyri (pFDR = 0.048) and between right caudate and multiple regions, including the left precentral/postcentral gyri (pFDR = 0.001), intracalcarine/precuneal/cuneal cortices (pFDR < 0.001), and fusiform gyrus (pFDR = 0.008). When fed, greater AP weight-gain risk was also associated with decreased connectivity between right anterior insula and ventromedial prefrontal cortex (pFDR = 0.002).

CONCLUSIONS

APs with higher weight-gain risk were associated with greater connectivity between reward-related regions and sensorimotor regions when fasted, perhaps relating to motor anticipation for consumption. Higher weight-gain risk APs were also associated with increased connectivity between reward, salience, and visual regions when fed, potentially reflecting greater desire for consumption following satiety.

Prebiotic diet changes neural correlates of food decision-making in overweight adults: a randomised controlled within-subject cross-over trial

OBJECTIVE

Animal studies suggest that prebiotic, plant-derived nutrients could improve homoeostatic and hedonic brain functions through improvements in microbiome-gut-brain communication. However, little is known if these results are applicable to humans. Therefore, we tested the effects of high-dosed prebiotic fibre on reward-related food decision-making in a randomised controlled within-subject cross-over study and assayed potential microbial and metabolic markers.

DESIGN

59 overweight young adults (19 females, 18-42 years, body mass index 25-30 kg/m2) underwent functional task MRI before and after 14 days of supplementary intake of 30 g/day of inulin (prebiotics) and equicaloric placebo, respectively. Short chain fatty acids (SCFA), gastrointestinal hormones, glucose/lipid and inflammatory markers were assayed in fasting blood. Gut microbiota and SCFA were measured in stool.

RESULTS

Compared with placebo, participants showed decreased brain activation towards high-caloric wanted food stimuli in the ventral tegmental area and right orbitofrontal cortex after prebiotics (preregistered, family wise error-corrected p <0.05). While fasting blood levels remained largely unchanged, 16S-rRNA sequencing showed significant shifts in the microbiome towards increased occurrence of, among others, SCFA-producing Bifidobacteriaceae, and changes in >60 predicted functional signalling pathways after prebiotic intake. Changes in brain activation correlated with changes in Actinobacteria microbial abundance and associated activity previously linked with SCFA production, such as ABC transporter metabolism.

CONCLUSIONS

In this proof-of-concept study, a prebiotic intervention attenuated reward-related brain activation during food decision-making, paralleled by shifts in gut microbiota.

TRIAL REGISTRATION NUMBER

NCT03829189.

Event-related Potentials Corresponding to Decision-making Under Uncertain Conditions

BACKGROUND

Decision-making is essential to human functioning, and resolving uncertainty is an essential part of decision-making. Impaired decision-making is present in many pathological conditions, and identifying markers of decision-making under uncertainty will provide a measure of clinical impact in future studies of therapeutic intervention for impaired decision-making.

OBJECTIVE

To describe EEG event-related potentials (ERPs) correlating with decision-making under uncertain conditions when compared with certain conditions.

METHOD

We used a novel card-matching task based on the Wisconsin Card Sorting Test to describe the neural correlates of uncertainty, as measured by EEG, in a group of 27 neurotypical individuals. We evaluated 500-ms intervals in the 2 seconds after card presentation to identify ERPs that are associated with maximal uncertainty compared with maximal certainty.

RESULTS

After correcting for multiple comparisons, we identified an ERP in the 500-1000-ms time frame (certain > uncertain, max amplitude 12.73 µV, latency 914 ms) in the left posterior inferior region of the scalp. We also found a P300-like ERP in the left frontal and parietal regions in the 0-500-ms time frame when the individuals received correct versus incorrect feedback (incorrect feedback > correct feedback, max amplitude 1.625 µV, latency 339 ms).

CONCLUSION

We identified an ERP in the 500-1000-ms time frame (certain > uncertain) that may reflect the resolution of uncertainty, as well as a P300-like ERP when feedback is presented (incorrect feedback > correct feedback). These findings can be used in future studies to improve decision-making and resolve uncertainty on the described markers.

Examination of Individual Differences in Susceptibility to Food Addiction using Alcohol and Addiction Research Domain Criteria (AARDoC): Recent Findings and Directions for the Future

Purpose of Review

Alcohol and Addiction Research Domain Criteria (AARDoC) is a transdiagnostic, circuits-based framework for studying addictive behaviors. We examined parallels in individual differences that might increase susceptibility to FA and other addictive disorders using the following units of analysis in AARDoC domains: craving, relative reinforcing value of food and attention bias in the incentive salience domain; decisional impulsivity (delay discounting) and inhibitory control (Go-No-Go, Conner’s Continuous Performance Test, and the flanker task) in the executive function domain; and emotion dysregulation and negative urgency in the negative emotionality domain.

Recent Findings

There are a number of parallels between FA and other addictions in the incentive salience and negative emotionality domains, but somewhat divergent findings in the executive function domain. Trauma appears to be an important environmental stressor in maintenance of FA.

Summary

AARDoC may be a useful organizing framework for studying addictions, including FA. Future studies should incorporate other units of analysis to better characterize FA.

Long-term changes in insula-mesolimbic structural and functional connectivity in obese patients after laparoscopic sleeve gastrectomy

OBJECTIVE

Brain imaging studies have shown insula-related functional and structural abnormalities in patients with obesity. Laparoscopic sleeve gastrectomy is currently an effective procedure for treating obesity, which promotes acute recovery of brain functional and structural abnormalities in obese patients. The aim of this study was to investigate the long-term impact of laparoscopic sleeve gastrectomy on insula-related structural and functional connectivity.

METHODS

Diffusion tensor imaging and resting-state functional magnetic resonance imaging were employed to investigate laparoscopic sleeve gastrectomy-induced changes in insula-related structural connectivity and corresponding resting-state functional connectivity in 25 obese patients prior to (PreLSG) and 12 months post-surgery (PostLSG₁₂).

RESULTS

Results showed significant increases in fractional anisotropy and axial diffusivity between the right insula and anterior cingulate cortex, and higher fractional anisotropy of left insula-putamen, left insula-caudate and anterior cingulate cortex-right posterior cingulate cortex/precuneus at PostLSG12 compared with PreLSG. There were significant negative correlations between axial diffusivity of right insula-anterior cingulate cortex and body mass index, and fractional anisotropy of right insula-anterior cingulate cortex with scores on external eating at PostLSG12. Anxiety and depressive status ratings were negatively correlated with fractional anisotropy of left insula-putamen at PostLSG12. In addition, there was a significant decrease in resting-state functional connectivity between left insula and left caudate.

CONCLUSIONS

These findings demonstrate long-term changes in insula-related structural and functional connectivity abnormalities promoted by laparoscopic sleeve gastrectomy, which highlight its strong association with long-term weight loss and improvement in eating behaviors.

Alterations in Functional and Structural Connectivity of Basal Ganglia Network in Patients with Obesity

Obesity is related to overconsumption of high-calorie (HiCal) food, which is modulated by brain reward and inhibitory control circuitries. The basal ganglia (BG) are a key set of nuclei within the reward circuitry, but obesity-associated functional and structural abnormalities of BG have not been well studied. Resting-state functional MRI with independent component analysis (ICA) and probabilistic tractography were employed to investigate differences in BG-related functional-(FC) and structural connectivity (SC) between 32 patients with obesity (OB) and 35 normal-weight (NW) participants. Compared to NW, OB showed significantly lower FC strength in the caudate nucleus within the BG network, and seed-based FC analysis showed lower FC between caudate and dorsolateral prefrontal cortex (DLPFC), which was negatively correlated with craving for HiCal food cues. Further SC analysis revealed that OB showed lower SC than NW between left caudate and left DLPFC as measured with fractional anisotropy (FA). Alterations in FC and SC between caudate and DLPFC in obese patients, which highlights the role of BG network in modulating the balance between reward and inhibitory-control.

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.

“Sound” Decisions: The Combined Role of Ambient Noise and Cognitive Regulation on the Neurophysiology of Food Cravings

Our ability to evaluate long-term goals over immediate rewards is manifested in the brain’s decision circuit. Simplistically, it can be divided into a fast, impulsive, reward “system 1” and a slow, deliberate, control “system 2.” In a noisy eating environment, our cognitive resources may get depleted, potentially leading to cognitive overload, emotional arousal, and consequently more rash decisions, such as unhealthy food choices. Here, we investigated the combined impact of cognitive regulation and ambient noise on food cravings through neurophysiological activity. Thirty-seven participants were recruited for an adapted version of the Regulation of Craving (ROC) task. All participants underwent two sessions of the ROC task; once with soft ambient restaurant noise (∼50 dB) and once with loud ambient restaurant noise (∼70 dB), while data from electroencephalography (EEG), electrodermal activity (EDA), and self-reported craving were collected for all palatable food images presented in the task. The results indicated that thinking about future (“later”) consequences vs. immediate (“now”) sensations associated with the food decreased cravings, which were mediated by frontal EEG alpha power. Likewise, “later” trials also increased frontal alpha asymmetry (FAA) —an index for emotional motivation. Furthermore, loud (vs. soft) noise increased alpha, beta, and theta activity, but for theta activity, this was solely occurring during “later” trials. Similarly, EDA signal peak probability was also higher during loud noise. Collectively, our findings suggest that the presence of loud ambient noise in conjunction with prospective thinking can lead to the highest emotional arousal and cognitive load as measured by EDA and EEG, respectively, both of which are important in regulating cravings and decisions. Thus, exploring the combined effects of interoceptive regulation and exteroceptive cues on food-related decision-making could be methodologically advantageous in consumer neuroscience and entail theoretical, commercial, and managerial implications.

The impact of environmental sounds on food reward

Wanting and liking are both components of food reward, but they manifest in fundamentally different neural substrates. While wanting denotes anticipatory and motivational behaviors, liking is associated with consummatory and hedonic experiences. These distinct constructs have also been quantitatively dissociated in behavioral paradigms. Indeed, internal, physiological, and interoceptive states affect the degree to which the food presented is valued. However, how contextual sensory cues might impact these appetitive and rewarding responses to food remains unexplored. In light of the increasing empirical focus on sound in food research, we investigated the influence of environmental soundscapes on explicit liking, explicit wanting, implicit wanting, choice frequency, and reaction time of healthy/unhealthy food using an online version of the Leeds Food Preference Questionnaire (LFPQ). Soft nature sounds and loud restaurant noises were employed to induce emotional relaxation and arousal respectively. One hundred and one healthy university students completed a repeated-measure design of the LFPQ; once with each soundscape playing in the background. Generalized linear mixed model analyses detected a significant interaction effect between soundscape and food type on choice frequency, yet the post hoc analyses did not reach significance. No interaction effects between soundscape and food type on wanting or liking were discovered. However, hypothesis-driven analyses found that nature sounds increased explicit liking of healthy (vs. unhealthy) foods, while no effect of soundscape on any wanting measures (explicit or implicit) were observed. Finally, exploratory analyses indicated that restaurant noise (vs. nature sound) induced faster response times for both healthy and unhealthy foods. The study exemplifies that in an online setting, contextual auditory manipulation of certain food reward measures and decision processes is feasible.

Global scientific production regarding behavioral addictions: An analysis of the literature from 1995 to 2019

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There is an increase in behavioral addiction research over the last 25 years.

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The most considerable increase has been in gambling and ITC related problems.

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Western countries are more interested in gambling and Asians in ITC related problems.

Aims

The increase in scientific interest in so-called behavioral addictions has been growing in recent years. For this reason, the aim of our study is to use bibliometric techniques to identify where and with what intensity these behaviors are being studied.

Methods

In October 2020, we conducted a search in the Web of Science Core Collection using a search equation designed to retrieve the articles that combine the general keywords of addiction with specific terms of the 7 groups of behavioral addictions analyzed (gambling; gaming; information and communication related disorders; and the so-called somatic addictions related to sex, shopping, food and sports). Articles published from 1995 to 2019 were included.

Results

We found 9199 distinct articles. Gambling was the most studied addiction, but Information and Technology Communication-related disorders (ITC) had the highest growth rate over the span of five five-year periods, followed by gaming and food addiction. In general, there was a growth rate of 130.46% in the research on behavioral addiction issues. By geographical region, the United States was the most productive country regarding all addictions, but Oceania had the highest proportion of publications per million population. There was a clear interest among Asian countries in studying problems related to ITC and gaming problems.

Conclusions

The importance of the seven behavioral addictions analyzed according to their growth rate in scientific research fields over the last 25 years was confirmed in our study. In addition, the differences in interest by geographical region show us that it is important to delve deeper into cultural particularities to better understand this phenomenon.

Delay Discounting in Established and Proposed Behavioral Addictions: A Systematic Review and Meta-Analysis

Steep delay discounting, or a greater preference for smaller-immediate rewards over larger-delayed rewards, is a common phenomenon across a range of substance use and psychiatric disorders. Non-substance behavioral addictions (e.g., gambling disorder, internet gaming disorder, food addiction) are of increasing interest in delay discounting research. Individual studies have reported steeper discounting in people exhibiting various behavioral addictions compared to controls or significant correlations between discounting and behavioral addiction scales; however, not all studies have found significant effects. To synthesize the published research in this area and identify priorities for future research, we conducted a pre-registered systematic review and meta-analysis (following PRISMA guidelines) of delay discounting studies across a range of behavioral addiction categories. The final sample included 78 studies, yielding 87 effect sizes for the meta-analysis. For studies with categorical designs, we found statistically significant, medium-to-large effect sizes for gambling disorder (Cohen’s d = 0.82) and IGD (d = 0.89), although the IGD effect size was disproportionately influenced by a single study (adjusted d = 0.53 after removal). Categorical internet/smartphone studies were non-significant (d = 0.16, p = 0.06). Aggregate correlations in dimensional studies were statistically significant, but generally small magnitude for gambling (r = 0.22), internet/smartphone (r = 0.13) and food addiction (r = 0.12). Heterogeneity statistics suggested substantial variability across studies, and publication bias indices indicated moderate impact of unpublished or small sample studies. These findings generally suggest that some behavioral addictions are associated with steeper discounting, with the most robust evidence for gambling disorder. Importantly, this review also highlighted several categories with notably smaller effect sizes or categories with too few studies to be included (e.g., compulsive buying, exercise addiction). Further research on delay discounting in behavioral addictions is warranted, particularly for categories with relatively few studies.

Temporal discounting as a candidate behavioral marker of obesity

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

Sounds Healthy: Modelling sound-evoked consumer food choice through visual attention

Food choice is a multifaceted construct that is not solely guided by our internal incentives. In fact, sensory scientist, consumer psychologists, and marketers have demonstrated that external ambient cues, including background music, can influence myriads of subconscious consumer behaviors, effectively leading to increased sales of food and beverages. However, the vast majority of literature in on this topic has thus far been confined to monocultural field studies in which the underlying mechanisms of food choice are unexplored. We therefore studied the explicit and implicit effects of custom-composed soundtracks on food choices and eye-movements in consumers from both 'East' and 'West'. Firstly, based on the results from a pre-study (N = 396), we composed a 'healthy' and 'unhealthy' soundtrack. Subsequently, we recruited 215 participants from China (n = 114) and Denmark (n = 101) respectively for in an in-laboratory eye-tracking food choice paradigm. For each culture, half of the participants listened to the 'healthy' soundtrack and the other half to the 'unhealthy' soundtrack during the experiment. Chi-square tests of independence revealed that across cultures, the healthy (vs. unhealthy) soundtrack led to more healthy food choices. Similarly, the generalized linear mixed models showed that the healthy soundtrack induced more and longer fixations on healthy (vs. unhealthy) food. Finally, a multiple mediation analysis signified a partial mediation effect of sound on food choice through the mediators of fixation duration, fixation count, and revisit count. Our results indicate that, with strategically chosen soundscapes, it is possible to influence consumers' decision-making processes and guide their attention towards healthier foods, providing valuable knowledge for local as well as global food business.

The Effects of Ethnically Congruent Music on Eye Movements and Food Choice-A Cross-Cultural Comparison between Danish and Chinese Consumers

Musical fit refers to the congruence between music and attributes of a food or product in context, which can prime consumer behavior through semantic networks in memory. The vast majority of research on this topic dealing with musical fit in a cultural context has thus far been limited to monocultural groups in field studies, where uncontrolled confounds can potentially influence the study outcome. To overcome these limitations, and in order to explore the effects of ethnically congruent music on visual attention and food choice across cultures, the present study recruited 199 participants from China (n = 98) and Denmark (n = 101) for an in-laboratory food choice paradigm with eye-tracking data collection. For each culture group, the study used a between-subject design with half of the participants listening to only instrumental "Eastern" music and the other half only listening to instrumental "Western" music, while both groups engaged in a food choice task involving "Eastern" and "Western" food. Chi-square tests revealed a clear ethnic congruency effect between music and food choice across culture, whereby Eastern (vs. Western) food was chosen more during the Eastern music condition, and Western (vs. Eastern) food was chosen more in the Western music condition. Furthermore, results from a generalized linear mixed model suggested that Chinese participants fixated more on Western (vs. Eastern) food when Western music was played, whereas Danish participants fixated more on Eastern (vs. Western) food when Eastern music was played. Interestingly, no such priming effects were found when participants listened to music from their own culture, suggesting that music-evoked visual attention may be culturally dependent. Collectively, our findings demonstrate that ambient music can have a significant impact on consumers' explicit and implicit behaviors, while at the same time highlighting the importance of culture-specific sensory marketing applications in the global food industry.