Relationships Among the Brain, the Digestive System, and Eating Behavior Workshop Summary (2015) / Chapter Skim
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3 Assessing the Science Behind Methodologies Being Used to Characterize Food as Addictive
3 Assessing the Science Behind Methodologies Being Used to Characterize Food as Addictive
Pages 31-66
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as addictive and addictive-like. To start the session, moderator Richard Mattes of Purdue University provided a brief historical overview of energy intake research and the shift in focus toward eating behavior.
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According to Ashley Gearhardt, addictive like eating behavior as defined by the YFAS has since been associated in many studies with eating-related problems such as higher current and lifetime BMI and emotional eating. Additionally, Gearhardt outlined how the YFAS has been associated with risk factors and mechanisms implicated in other addictive disorders, such as hyperreactivity of reward-related neural regions to food cues, higher rates of impulsivity, and elevated craving.
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WHAT IMAGING TECHNOLOGIES REVEAL ABOUT FOOD BEHAVIORS: PERSPECTIVE 12 "The obesity epidemic is a neurobehavioral problem that stems from a vulnerable brain in an unhealthy food environment." -- Giles Yeo Inasmuch as the brain is a key facet of Giles Yeo's definition of the obesity epidemic, Dana Small began, neuroimaging will be critical to understanding how the modern food environment is engaging appetitive circuits, hedonic circuits, and their interaction. Small discussed how neuroimaging research is being used to understand food cue reactivity and its role in obesity.
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Together, these results suggest that food cue reactivity is a power ul f predictor of eating behavior and can be used to predict weight gain. Regulation of Food Cue Reactivity: Importance of Postingestive Signaling In an effort to understand what regulates food cue reactivity, Small and her research team have been using a "flavor nutrient conditioning" paradigm.
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. A second group received the same flavor plus maltodextrin, a condition with postoral effects but no oral effects (because maltodextrin is tasteless and odorless to humans)
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While the greatest changes were observed when both postoral and oral effects occurred, the lack of change seen in the flavor plus aspartame group and the changes seen in the flavor plus maltodextrin group together suggest that postoral effects by themselves are both necessary and sufficient for inducing flavor-nutrient association learning and for increasing the reward value of a flavor. Postingestive Signaling: The Role of Glucose Metabolism Given the evidence accumulated thus far, it appears clear that some postoral effect is a critical signal for flavor-nutrient association learning.
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Small concluded with an overview of additional studies her laboratory is undertaking to better understand what drives food cue reactivity. Summary In summary, Small emphasized that heightened food cue reactivity as assessed by fMRI is associated with BMI and eating in the absence of hunger and is a reliable biomarker of susceptibility to weight gain.
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It is time, she said, to begin integrating the characteristics of foods with their physiological effects in the body and how those physiological effects, in turn, are regulating brain circuits. WHAT IMAGING TECHNOLOGIES REVEAL ABOUT FOOD BEHAVIORS: PERSPECTIVE 23 Whether imaging data reveal anything about food behaviors, particularly "food addiction," is open to debate in Hisham Ziauddeen's opinion.
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The Importance of Task Although Ziauddeen focused mainly on phenotype and process, he briefly highlighted the importance of task, which in his opinion is highly relevant when considering complex stimuli such as food. As an example, Ziauddeen described a motivational task that he and his research team developed for examining low- or high-fat food versus nonfood (Ziauddeen et al., 2014)
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eating disorders, mainly binge eating disorder but also bulimia nervosa on occasion; and (3) food addiction itself, based on the YFAS, which itself is based on the criteria for substance dependence in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV)
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. In these samples, there is a strong concordance with diagnosed binge eating disorder, raising the possibility that the scale may be
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In summary, Ziauddeen urged greater consideration of the limitations of phenotypes being studied. The Processes Regarding processes at play, neuroimaging studies on food addiction are guided largely by what is known about drug addiction.
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For more common levels of obesity, the evidence is unclear. In a recent review of functional neuroimaging studies examining obesity, binge eating disorder, BMI (as a continuous variable)
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2005. How can drug addiction help us understand obesity?
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The individuals were provided with either a chocolate milkshake or a neutral tasteless solution while in the scanner. Based on the model described above from the drug addiction field, one would expect an enhanced anticipatory response to cues that predict the chocolate milkshake and a decreased consumption response to actual receipt of the milkshake in individuals identified as being addicted to food.
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This phenomenon has raised the question of whether an addictive-like process may contribute to this chronic relapsing pattern. Additionally, there has been greater clinical acknowledgment that binge eating disorder, which entails repeated periods during which people lose control of their food consumption despite a desire to maintain control, is a verifiable mental health issue.
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Thus, as with drugs of abuse, these foods may be more likely to trigger an addictive process compared with more naturally occurring foods. Identifying "Addictive Eaters" To further investigate the hypothesis that an addictive process contributes to problematic eating, Gearhardt and her colleagues focused on methodologically sound ways of identifying "addictive eaters." When she first started exploring this question, Gearhardt found that existing methods
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Treating people with binge eating disorder involves minimizing the restraint around eating behavior and teaching them that there is no "good" or "bad" food. From this perspective, it is only the way the person relates to food that is a problem; the attributes of the food (e.g., high sugar, high fat)
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"There seems to be a difference between these items," she said. Thus, both the mechanisms and treatments for binge eating disorder and addictive-like eating are notably different, which does not make binge eating an optimal proxy for food addiction.
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Thus, while the development of the YFAS does not prove that food addiction is a valid concept, Gearhardt noted, it does provide a more methodologically sound tool than has previously been available for evaluating empirically whether an addictive process is contributing to compulsive eating behavior. A Review of YFAS Literature Gearhardt noted that since the YFAS was published in 2009, many studies have used it to examine addictive-like eating.
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In the future, Gearhardt would like to test these findings in a sample with more severe levels of food addiction, as few participants in this study met the clinical cut-off point for food addiction. Given the large effect sizes found in this study, it is likely that more severely addicted eaters may exhibit even more differences in neural function in response to food cues and consumption.
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Answering this question and determining the socioeconomic implications (e.g., living in a neighborhood of lower socioeconomic status and having access only to certain types of foods) will be "incredibly important" for treating and preventing obesity and eating disorders, Gearhardt said.
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It is considered essential for drug addicion and is important for "food addiction" as well, which is why, t in the view of the DSM-5 substance use disorder committee, binge eating disorder comes the closest among eating problems to "food addiction." Another change in the DSM-5 criteria for substance use disorder is the addition of craving for the substance. Craving was added based on brain imaging data showing that people who are in treatment for any kind of addiction tend to have a craving for the substance that can last for years.
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Together, these results suggest that the self-administration value of sweetened condensed milk does not last as it does with alcohol or cocaine, even though all three substances are activating the same part of the brain -- the nucleus accumbens and ventral striatum. O'Brien emphasized that while human brain imaging is useful (in fact, gambling was added to the DSM-5 list of addictions based on human brain imaging data)
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I am sure that if I were in a brain scanner, you would see activation of my ventral striatum and nucleus accumbens. But does that mean it is an addiction?
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56 THE BRAIN, THE DIGESTIVE SYSTEM, AND EATING BEHAVIOR ASI Severity Panel of a Drug-Dependent Physician 90 80 80 70 60 Severity 50 40 30 20 20 10 10 10 10 0 0 Drug Med Emp Legal Fam Psych Problem Area ASI Severity Panel of a Drug-Dependent Teen Mother 90 80 70 60 Severity 50 40 30 20 10 0 Drug Med Emp Legal Fam Psych Problem Area FIGURE 3-2 Severity of symptoms for six of the seven problem areas, or domains, associated with addiction, based on the Addiction Severity Index (ASI) , for two individuals.
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Substance in Food: A Key Research Challenge An audience member observed that discussions of drug addiction generally do not revolve around drug addiction per se; rather, the focus usually is on addiction to specific drugs, such as cocaine, heroin, and so on. The audience member asked whether there is a specific food-related chemical reaction that is having an impact when the brain's reward system overrides its satiety system.
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Small reiterated that addictivelike eating behavior is a confluence of multiple factors. "It is not just the nature of the food product," she said.
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Gearhardt replied that her research team is currently investigating that question. Based on the drug addiction literature and experiments conducted with sham feeding, she suspects that a metabolic effect is involved.
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Might it be the case that people who become addicted have an underlying problem that results in the expression of addictive behavior? Ziauddeen responded that at least in the case of drug addiction, predisposing factors increasingly are being viewed as important.
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O'Brien noted that this issue of potency is another of the significant difficulties in extrapolating from drugs to food. The oral mechanism of food consumption makes it very different from either intralung or intravenous administration of addictive drugs.
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An audience member observed that today's children eat more un supervised meals than children of past generations and questioned whether insufficient parenting skills related to etiquette, the use of utensils, and so on may be contributing to unhealthy eating behaviors in children. She suggested conducting future eating behavior studies with children aimed at determining whether the occurrence of family meals (as opposed to un super ised meals)
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He suggested that researchers studying eating behavior adopt a similar approach, that is, collect brain imaging data in a very large database and look for correlations with individual questions from the YFAS. In the same studies, researchers could also look for biomarkers that correlate either with the activation seen in the brain imaging or responses to the questions.
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However, Ziauddeen agreed that many neuroimaging studies ask dichotomous questions and that the field needs to move toward greater use of continuous measures. Reliability of the YFAS Scores When asked by Mattes about a test-retest correlation for the YFAS over extended periods of time, Gearhardt noted that a student of hers is currently collecting those data.
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Gearhardt explained that the cognitive-behavioral approach currently used with people who have binge eating disorder is based on cues and identification of what triggers those cues. One of the goals is to help individuals avoid situations, such as being in an extreme fasting state, that trigger binge eating.
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