State and trait influences on attentional bias to food-cues: The role of hunger, expectancy, and self-perceived food addiction

Increased meso-striatal connectivity mediates trait impulsivity in FTO variant carriers

Objective

While variations in the first intron of the fat mass and obesity-associated gene (FTO, rs9939609 T/A variant) have long been identified as a major contributor to polygenic obesity, the mechanisms underlying weight gain in risk allele carriers still remain elusive. On a behavioral level, FTO variants have been robustly linked to trait impulsivity. The regulation of dopaminergic signaling in the meso-striatal neurocircuitry by these FTO variants might represent one mechanism for this behavioral alteration. Notably, recent evidence indicates that variants of FTO also modulate several genes involved in cell proliferation and neuronal development. Hence, FTO polymorphisms might establish a predisposition to heightened trait impulsivity during neurodevelopment by altering structural meso-striatal connectivity. We here explored whether the greater impulsivity of FTO variant carriers was mediated by structural differences in the connectivity between the dopaminergic midbrain and the ventral striatum.

Methods

Eighty-seven healthy normal-weight volunteers participated in the study; 42 FTO risk allele carriers (rs9939609 T/A variant, FTO ⁺ group: AT, AA) and 39 non-carriers (FTO ^- group: TT) were matched for age, sex and body mass index (BMI). Trait impulsivity was assessed via the Barratt Impulsiveness Scale (BIS-11) and structural connectivity between the ventral tegmental area/substantia nigra (VTA/SN) and the nucleus accumbens (NAc) was measured via diffusion weighted MRI and probabilistic tractography.

Results

We found that FTO risk allele carriers compared to non-carriers, demonstrated greater motor impulsivity (p = 0.04) and increased structural connectivity between VTA/SN and the NAc (p< 0.05). Increased connectivity partially mediated the effect of FTO genetic status on motor impulsivity.

Conclusion

We report altered structural connectivity as one mechanism by which FTO variants contribute to increased impulsivity, indicating that FTO variants may exert their effect on obesity-promoting behavioral traits at least partially through neuroplastic alterations in humans.

Disconnect between sympathetically-induced hunger suppression and consumption among highly restrained eaters following stress

Despite emphasis on findings suggesting restrained eaters increase food consumption under stress, unrestrained eaters' reduction in intake is more robust. Early proposals asserted unrestrained eaters significantly reduced intake after certain threats due to the hunger-inhibiting effects of autonomic influences, presuming unrestrained eaters are more responsive to these effects and restrained eaters rely less on physiological cues for eating. However, scant empirical evidence has substantiated these claims. This study examined whether a sequence exists whereby stress elicits autonomic activation, autonomic activation impacts hunger, and hunger then impacts eating, with dietary restraint altering the hunger-intake link. It was hypothesized that sympathetic nervous system activation would be greatest when ongoing safety from stress was uncertain, sympathetic activation would be linked to reduced hunger, and lower hunger would be associated with attenuated intake. Restraint, conceptualized via Hagan et al.'s (2017) latent restraint factors, was hypothesized to reduce the association between hunger and intake. Female participants (n = 147) were randomized to a stress + certain safety, stress + uncertain safety, or control condition. Sympathetic nervous system activity was recorded prior to a bogus taste test, which quantified ad libitum consumption of highly-palatable snack foods post-stress. Only the stress + uncertain safety condition exhibited greater sympathetic nervous system activity than the control condition. A significant index of moderated serial mediation emerged for Preoccupation with Dieting and Weight-Focused Restraint in the stress + uncertain safety condition. Though sympathetic activation decreased hunger similarly regardless of dietary restraint, only less restrained individuals significantly decreased intake. More restrained individuals ate more despite experiencing lower hunger. The disconnect between hunger and intake in more restrained eaters suggests that focus on enhancing attunement to hunger may yield greater benefit than enhancing restraint. 281 words.

A Systematic Review of Eye-Tracking Studies of Gambling-Related Attentional Biases

Previous research has identified attentional biases towards addiction-related stimuli, including gambling-related stimuli. Eye-tracking is considered the gold standard methodology for measuring attentional biases, yet no review to date has examined its use in measuring gambling-related attentional biases. This systematic review synthesized the literature using eye-tracking to examine attentional biases among people who gamble. We reviewed articles from Web of Science and PubMed that were published from 1990 to 2021. A total of 11 articles were included, with sample sizes ranging from 38 to 173 participants. Of these studies, seven examined attentional biases for gambling-related visual stimuli. These seven studies provided support that gambling can result in the development of an attentional bias for gambling-related stimuli. With respect to correlates of gambling-related attentional biases, there were mixed results. Some studies identified significant positive associations between gambling-related attentional biases and psychosocial variables, such as problem gambling severity, gambling expectancies, gambling cravings, gambling motives, depressive symptom severity, alcohol use severity, daily stress, affective impulsivity, and immersion. Four studies examined attentional biases for responsible gambling messaging and advertisements, finding that both people who do and do not gamble attend less to responsible gambling messaging compared to other types of information such as the betting odds. Research using eye-tracking to examine attentional biases among people who gamble is in its infancy. Yet, the preliminary results support the identification of attentional biases using the gold-standard methodology. Further studies are needed to examine the correlates and potential clinical utility of assessing gambling-related attentional biases using eye-tracking.

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.

Measuring Food-Related Attentional Bias

Objective: Food-related attentional bias has been defined as the tendency to give preferential attention to food-related stimuli. Attentional bias is of interest as studies have found that increased attentional bias is associated with obesity; others, however, have not. A possible reason for mixed results may be that there is no agreed upon measure of attentional bias: studies differ in both measurement and scoring of attentional bias. Additionally, little is known about the stability of attentional bias over time. The present study aims to compare attentional bias measures generated from commonly used attentional bias tasks and scoring protocols, and to test re-test reliability.

Methods: As part of a larger study, 69 participants (67% female) completed two food-related visual probe tasks at baseline: lexical (words as stimuli), and pictorial (pictures as stimuli). Reaction time bias scores (attentional bias scores) for each task were calculated in three different ways: by subtracting the reaction times for the trials where probes replaced (1) neutral stimuli from the trials where the probes replaced all food stimuli, (2) neutral stimuli from the trials where probes replaced high caloric food stimuli, and (3) neutral stimuli from low caloric food stimuli. This resulted in three separate attentional bias scores for each task. These reaction time results were then correlated. The pictorial visual probe task was administered a second time 14-days later to assess test-retest reliability.

Results: Regardless of the scoring use, lexical attentional bias scores were minimal, suggesting minimal attentional bias. Pictorial task attentional bias scores were larger, suggesting greater attentional bias. The correlation between the various scores was relatively small (r = 0.13–0.20). Similarly, test-retest reliability for the pictorial task was poor regardless of how the test was scored (r = 0.20–0.41).

Conclusion: These results suggest that at least some of the variation in findings across attentional bias studies could be due to differences in the way that attentional bias is measured. Future research may benefit from either combining eye-tracking measurements in addition to reaction times.

Eye-tracking research on sensory and consumer science: A review, pitfalls and future directions

Visual processing is a core cognitive element of sensory and consumer science. Consumers visually attend to food types, packaging, label design, advertisements, supermarket shelves, food menus, and other visible information. During the past decade, sensory and consumer science have used eye tracking to elucidate visual processing by consumers. This review paper summarizes earlier findings in terms of bottom-up (i.e., stimulus-driven) processing such as visual salience, size, and top-down (i.e., goal-driven) processing such as goals, task instructions, task complexity, and emotions. Downstream effects of gaze on choice are also reviewed. Pitfalls and future directions of eye-tracking research on sensory and consumer science are also discussed.

Compensatory health beliefs and unhealthy snack consumption in daily life

Compensatory health beliefs (CHBs) are beliefs that an unhealthy behavior (unhealthy eating) can be compensated for by engaging in a healthy behavior (physical activity). Previous research focused on CHBs as rather stable beliefs (trait). Some studies indicated that situation-specific CHBs (state) might be important in situations, in which people are confronted with an unhealthy snack. This study aims to investigate the association between CHBs and unhealthy snack consumption in daily life with a special focus on the distinction between trait and state CHBs. Overall, N = 45 participants (66.7% female; age: 18-45 years, M = 21.9) received a link to an online questionnaire five times daily for seven consecutive days (n = 1575 possible diary entries). They reported unhealthy snack consumption, state and trait CHBs concerning the compensation with subsequent eating behavior and physical activity. The results showed that trait and state CHBs were significantly positively related to unhealthy snack consumption in daily life. Different effects appeared for CHBs concerning the compensation with subsequent eating behavior compared to the compensation with physical activity. This study demonstrates that both, state and trait CHBs are important for unhealthy snack consumption in daily life. Findings emphasize the need for further daily diary approaches to understand the temporal sequence of state CHBs that could further explain the use of CHBs as a maladaptive strategy for unhealthy eating.

Attentional bias to food varies as a function of metabolic state independent of weight status

Eating behaviour requires that internal metabolic changes are recognized by the central nervous system which regulates brain responses to food cues. This function may be altered in obesity. The aim of this study was to examine potential differences in neurocognitive responses to visual food cues as a function of metabolic state and weight status. A crossover study with two participant groups was conducted, one group with normal-weight (n = 20) and one group with overweight/obesity (n = 22), who completed a novel battery of neurocognitive tests assessing food-cue elicited behavior in both fasted and fed states. The test battery included a visual-dot probe task (VPT), a stimulus-response compatibility task (SRCT) and an implicit association task (IAT). Results from the VPT showed a significant main effect of metabolic state on attentional bias (F(1,40) = 9.90, p = .003, η²_p = .198), with participants in the fasted state showing a significantly greater attentional bias for food stimuli than in the fed state. No significant main effect of metabolic state on approach food bias, assessed via the SRCT, or implicit attitudes to food cues, assessed via the IAT, was found and overall, no difference in neurocognitive processing of food cues was demonstrated between participant groups. In the fed state, attentional bias to food cues decreases in both normal-weight controls and participants with overweight/obesity, indicating that changes in current metabolic state can be reflected in attentional processing of visual food cues independently of weight status. Neurocognitive tasks which can effectively and sensitively identify differences in food cue perception according to changes in metabolic status will be useful tools in exploring more complicated interactions between homeostatic and hedonic drives of food intake.

Fat Addiction: Psychological and Physiological Trajectory

Obesity has become a major public health concern worldwide due to its high social and economic burden, caused by its related comorbidities, impacting physical and mental health. Dietary fat is an important source of energy along with its rewarding and reinforcing properties. The nutritional recommendations for dietary fat vary from one country to another; however, the dietary reference intake (DRI) recommends not consuming more than 35% of total calories as fat. Food rich in fat is hyperpalatable, and is liable to be consumed in excess amounts. Food addiction as a concept has gained traction in recent years, as some aspects of addiction have been demonstrated for certain varieties of food. Fat addiction can be a diagnosable condition, which has similarities with the construct of addictive disorders, and is distinct from eating disorders or normal eating behaviors. Psychological vulnerabilities like attentional biases have been identified in individuals described to be having such addiction. Animal models have provided an opportunity to explore this concept in an experimental setting. This discussion sheds light on fat addiction, and explores its physiological and psychological implications. The discussion attempts to collate the emerging literature on addiction to fat rich diets as a prominent subset of food addiction. It aims at addressing the clinical relevance at the community level, the psychological correlates of such fat addiction, and the current physiological research directions.