Modified sham feeding of sweet solutions in women with anorexia nervosa

Sweet, Salty, and Umami Taste Sensitivity and the Hedonic Perception of Taste Sensations in Adolescent Females with Anorexia Nervosa

OBJECTIVE

The aim of this study was to perform analysis of sensitivity to sweet, salty, and umami tastes based on three measurement methods and of the hedonic perception of taste sensations in adolescent females with anorexia nervosa (AN). The aim of the research was to confirm the results of other authors in terms of the perception of sweet and salty taste in patients with AN, and then develop knowledge about the perception of umami taste, which is still insufficiently studied.

METHOD

A total of 110 females with an age ranging from 13 to 19 years, including 50 newly diagnosed patients with a restrictive subtype of AN and 60 healthy controls participated in gustatory research involving analyses of taste perception (recognition thresholds, ability to identify the taste correctly, taste intensity, and hedonic response) applying the sip and spit method.

RESULTS

Females with AN showed reduced sensitivity to salty taste and increased sensitivity to umami taste and, more often than healthy controls, wrongly classified the taste of solutions with a low sucrose concentration. Patients with AN assessed the sodium chloride and monosodium glutamate tastes less negatively than did control participants, and they did not show differences in their hedonic assessment of sucrose.

CONCLUSIONS

The taste sensitivity alterations in females with AN demonstrated in this paper do not entail decreased hedonic assessment of taste experiences. Based on our results, we cannot consider the observed variation in taste sensitivity in patients with AN to be a factor that increases their negative attitude toward food consumption.

Gastrointestinal Interoception in Eating Disorders: Charting a New Path

PURPOSE OF REVIEW

Abnormal interoception has been consistently observed across eating disorders despite limited inclusion in diagnostic conceptualization. Using the alimentary tract as well as recent developments in interoceptive neuroscience and predictive processing as a guide, the current review summarizes evidence of gastrointestinal interoceptive dysfunction in eating disorders.

RECENT FINDINGS

Eating is a complex process that begins well before and ends well after food consumption. Abnormal prediction and prediction-error signals may occur at any stage, resulting in aberrant gastrointestinal interoception and dysregulated gut sensations in eating disorders. Several interoceptive technologies have recently become available that can be paired with computational modeling and clinical interventions to yield new insights into eating disorder pathophysiology. Illuminating the neurobiology of gastrointestinal interoception in eating disorders requires a new generation of studies combining experimental probes of gut physiology with computational modeling. The application of such techniques within clinical trials frameworks may yield new tools and treatments with transdiagnostic relevance.

Neural Processing of Disorder-Related Stimuli in Patients with Anorexia Nervosa: A Narrative Review of Brain Imaging Studies

Abnormalities and alterations in brain function are commonly associated with the etiology and maintenance of anorexia nervosa (AN). Different symptom categories of AN have been correlated with distinct neurobiological patterns in previous studies. The aim of this literature review is to provide a narrative overview of the investigations into neural correlates of disorder-specific stimuli in patients with AN. Although findings vary across studies, a summary of neuroimaging results according to stimulus category allows us to account for methodological differences in experimental paradigms. Based on the available evidence, the following conclusions can be made: (a) the neural processing of visual food cues is characterized by increased top-down control, which enables restrictive eating, (b) increased emotional and reward processing during gustatory stimulation triggers disorder-specific thought patterns, (c) hunger ceases to motivate food foraging but instead reinforces disorder-related behaviors, (d) body image processing is related to increased emotional and hedonic reactions, (e) emotional stimuli provoke increased saliency associated with decreased top-down control and (f) neural hypersensitivity during interoceptive processing reinforces avoidance behavior. Taken together, studies that investigated symptom-specific neural processing have contributed to a better understanding of the underlying mechanisms of AN.

Taste sensitivity in anorexia nervosa: A systematic review

OBJECTIVE

There is evidence for altered processing of taste in anorexia nervosa, particularly in the areas of reward processing and hedonic sensitivity. However, research on whether people with anorexia nervosa identify taste stimuli accurately, known as taste sensitivity, has yielded mixed findings. The objective of this study was to synthesize the literature on taste sensitivity in this disorder to provide a basis for future discussion on whether altered taste sensitivity may be also implicated in wider atypical taste processing in anorexia.

METHOD

Electronic databases were searched systematically to identify published research examining taste sensitivity in anorexia. Search terms were "anorexia nervosa", or "eating disorder", combined with "taste". 18 studies met inclusion criteria.

RESULTS

The review of the findings suggest that individuals with AN may experience reduced taste sensitivity that may improve following recovery. However, there was a significant variability in results across studies, potentially reflecting methodological problems including low sample sizes, experimental designs, and uncontrolled confounding variables.

DISCUSSION

This review suggests that altered taste sensitivity could represent a component in the wider altered taste processing observed in anorexia nervosa. However, the heterogeneity of findings highlight the need for future research to consider methodological issues raised by this review.

The real-life costs of emotion regulation in anorexia nervosa: a combined ecological momentary assessment and fMRI study

Regulation of emotions is necessary for successful attainment of short-term and long-term goals. However, over-regulation may also have its costs. In anorexia nervosa (AN), forgoing food intake despite emaciation and endocrine signals that promote eating is an example of "too much" self-control. Here we investigated whether voluntary emotion regulation in AN patients comes with associated disorder-relevant costs. Thirty-five patients with acute AN and thirty-five age-matched healthy controls (HCs) performed an established emotion regulation paradigm during functional magnetic resonance imaging after an overnight fast. The task required reducing emotions induced by positively valenced pictures via distancing. We calculated a neural regulation score from responses recorded in a reward-related brain region of interest (ventral striatum; VS) by subtracting activation measured on "positive distance" trials from that elicited under the "positive watch" (baseline) condition. Complementing the imaging data, we used ecological momentary assessment (EMA) to probe disorder-related rumination and affect six times/day for 2 weeks following the scanning session. The neural regulation score indicating reduced VS activation during emotion regulation was used as a predictor in hierarchical linear models with EMA measures as outcomes. No group differences in neural activity were found for the main contrasts of the task. However, regulation of VS activity was associated with increased body-related rumination and increased negative affect in AN, but not in HC. In line with this finding, correlational analysis with longitudinal BMI measurements revealed a link between greater VS regulation and poorer treatment outcome after 60 and 90 days. Together, these results identify a neural correlate of altered emotion regulation in AN, which seems to be detrimental to psychological well-being and may interfere with recovery.

A sipometer for measuring motivation to consume and reward value of foods and beverages in humans: Description and proof of principle

New methods, derived from animal work, for measuring food reward value (i.e. reinforcing value of food), and motivation (i.e. strength of desire) to consume, in humans are described and validated. A sipping device (sipometer) was developed that permits access to a liquid food or beverage on two reward schedules: continuous reinforcement (CR) and progressively increasing time spent exerting pressure on a straw (PR-schedule). In addition, a pictorial scale showing a cup, from which the 'amount wanted' could be marked was used to pre-test potential consumption. Intake, time spent sipping, breakpoint, and pressure exerted were the main dependent variables measured. Three pilot experiments were conducted. In Experiment 1, participants (n=8) consumed yogurt shakes after a 1-h or 21-h food deprivation period on both schedules. In Experiment 2, participants (n=8) sham-consumed (i.e. spit out) sweet and non-sweet beverages, utilizing both schedules. In Experiment 3, sham-consuming sweet and non-sweet beverages on both schedules and working for shake on the PR schedule were repeated, after three nights of either habitual sleep or short sleep duration (n=7) in a crossover design. In Experiment 1, participants sipped longer after 21-h vs. 1-h of food deprivation (13±3.0 vs. 8.0±2.1s; p=0.04), on the PR schedule. In Experiment 2, sham-intake (p=0.01) and sipping time (p=0.04) were greater for sweet than non-sweet beverages on the PR schedule and a similar, though not conventionally significant, effect was observed for exerted pressure (p=0.09). In both Experiment 2 and Experiment 3 after habitual sleep, on the PR schedule, cumulative pressure difference between sweet and non-sweet beverage increased with difference in amount wanted in the taste test. In contrast, after short sleep participants were less willing to work for sweet taste as their wanting increased, suggesting that sleep deprivation raises desire, but lowers behavioral output. Taken together these results demonstrate that the sipometer and associated ratings are reliable and useful measures of motivation to consume and reward value in humans. Participants were more motivated to obtain access to sweet beverages, especially when these were better liked than to obtain access to non-sweet beverages.

VIDEOFLUOROSCOPIC EVALUATION OF SWALLOWS IN ANOREXIA NERVOSA

BACKGROUND

There are some studies in the literature about the feeding behavior and masticatory process in patients with feeding disorders; however, it is not very well known if there are alterations in oral-pharyngeal swallowing dynamics in subjects with anorexia nervosa.

OBJECTIVE

To evaluate the oral and pharyngeal bolus transit in patients with anorexia nervosa.

METHODS

The study was conducted with 8 individuals clinically diagnosed and in treatment for restricting-type anorexia nervosa (seven women and one man), and 14 healthy individuals with no digestive or neurological symptoms (10 women, 4 men). Swallows were evaluated by videofluoroscopy with three swallows of 5 mL liquid bolus and three swallows of 5 mL paste bolus consistency, given in a random sequence. The participants were asked after each swallow about the sensation of the bolus passage.

RESULTS

In the analysis of oral-pharyngeal transit duration, the mean duration of pharyngeal transit with paste bolus in patients with anorexia was shorter than in healthy volunteers (P=0.02). In the duration of movement of the hyoid bone, longer movement was observed in anorexia than in healthy volunteers with liquid bolus (P=0.01). With liquid bolus, five (62.5%) patients and one (7.1%) control had sensation of the bolus passage (P<0.05).

CONCLUSION

There seems to be no important alterations of swallowing in subjects with anorexia nervosa, although the results suggest that pharyngeal transit has shorter duration than that seen in healthy volunteers and the hyoid movement duration is longer in patients than in healthy volunteers. Fast pharyngeal transit may be the cause of bolus transit perception in patients with anorexia nervosa.

Assessment of the motivation to use artificial sweetener among individuals with an eating disorder

Eating disorders are associated with a range of abnormalities in eating behavior. Some individuals consume large amounts of non-caloric artificial sweeteners, suggesting abnormalities in appetitive responding. The current study aimed to quantify hedonic and motivating effects of artificial sweetener in individuals with and without an eating disorder. Two laboratory studies were conducted. Hedonic preference was estimated using the number of artificial sweetener packets (0-10) added to unsweetened cherry flavored Kool-Aid (study 1). Motivation to obtain sweetener was assessed by a progressive ratio (PR) work task (study 2). Ninety-three participants (25 anorexia nervosa restricting type (AN-R), 23 AN binge/purge type (AN-B/P), 20 bulimia nervosa (BN), and 25 normal controls (NC)) completed the study. No significant difference in hedonic preference was found among participant groups. Work completed at the PR task ranged from 0 to 9500 key-board presses. The AN-B/P group had a significantly higher breakpoint and performed significantly more work for sweetener compared to the BN and NC groups. Among AN-B/P and AN-R participants, the preferred number of Equal packets was significantly correlated with the breakpoint and total work. The increased amount of work for sweetener among individuals with AN-B/P supports an enhanced reward value of sweet taste in this population, and suggests that the characteristic food avoidance in AN cannot be accounted for by decreased reward value of all taste-related stimuli. This study also supports the novel application of a PR ratio task to quantify the motivating effect of sweet taste among individuals with an eating disorder.

Nasogastric Tube Feeding for Individuals With Anorexia Nervosa: An Integrative Review

BACKGROUND

The use of nasogastric (NG) feeding in individuals with anorexia nervosa (AN) is endorsed by national professional organizations; however, no guidelines currently exist.

OBJECTIVES

The objectives of this review were to identify and evaluate outcomes of NG feedings for individuals with AN and to develop recommendations for future research, policy, and practice.

DESIGN

An integrative review of the research literature was conducted.

RESULTS

Of the 19 studies reviewed, all indicated short-term weight gain following NG feeding. Four studies examined adherence; nearly 30% of subjects were nonadherent as evidenced by tube manipulation. Seven studies reported psychiatric outcomes, suggesting NG feeding reduces eating disorder behaviors but not overall symptomology.

CONCLUSIONS

NG feeding promotes short-term weight gain; however, long-term outcomes are poorly understood. Future research, using rigorous methods, is still needed to inform practice.

Chew and Spit (CHSP): a systematic review

BACKGROUND

This systematic review is an evaluation of the empirical literature relating to the disordered eating behaviour Chew and Spit (CHSP). Current theories postulate that CHSP is a symptom exhibited by individuals with recurrent binge eating and Bulimia Nervosa.

AIMS

The review aimed to identify and critically assess studies that have examined the distribution of CHSP behaviour, its relationship to eating disorders, its physical and psychosocial consequences and treatment.

METHODS

A systematic database search with broad inclusion criteria, dated to January 2016 was conducted. Data were extracted by two authors and papers appraised for quality using a modified Downs and Black Quality Index.

RESULTS

Nine studies met the inclusion criteria. All were of clinical samples and majority (n = 7) were of low quality. The pathological action of chewing food but not swallowing was reported more often in those with restrictive type eating disorders, such as Anorexia Nervosa, than binge eating type disorders. CHSP also was reported to be an indicator of overall severity of an eating disorder and to appear more often in younger individuals. No studies of treatment were found.

CONCLUSIONS

Conclusions were limited due to the low quality and small numbers of studies based on clinical samples only. Further research is needed to address gaps in knowledge regarding the physiological, psychological, social, socioeconomic impact and treatment for those engaging in CHSP.

Elevated cognitive control over reward processing in recovered female patients with anorexia nervosa

BACKGROUND

Individuals with anorexia nervosa are thought to exert excessive self-control to inhibit primary drives.

METHODS

This study used functional MRI (fMRI) to interrogate interactions between the neural correlates of cognitive control and motivational processes in the brain reward system during the anticipation of monetary reward and reward-related feedback. In order to avoid confounding effects of undernutrition, we studied female participants recovered from anorexia nervosa and closely matched healthy female controls. The fMRI analysis (including node-to-node functional connectivity) followed a region of interest approach based on models of the brain reward system and cognitive control regions implicated in anorexia nervosa: the ventral striatum, medial orbitofrontal cortex (mOFC) and dorsolateral prefrontal cortex (DLPFC).

RESULTS

We included 30 recovered patients and 30 controls in our study. There were no behavioural differences and no differences in hemodynamic responses of the ventral striatum and the mOFC in the 2 phases of the task. However, relative to controls, recovered patients showed elevated DLPFC activity during the anticipation phase, failed to deactivate this region during the feedback phase and displayed greater functional coupling between the DLPFC and mOFC. Recovered patients also had stronger associations than controls between anticipation-related DLPFC responses and instrumental responding.

LIMITATIONS

The results we obtained using monetary stimuli might not generalize to other forms of reward.

CONCLUSION

Unaltered neural responses in ventral limbic reward networks but increased recruitment of and connectivity with lateral-frontal brain circuitry in recovered patients suggests an elevated degree of selfregulatory processes in response to rewarding stimuli. An imbalance between brain systems subserving bottom-up and top-down processes may be a trait marker of the disorder.

What contributes to excessive diet soda intake in eating disorders: appetitive drive, weight concerns, or both?

Excessive diet soda intake is common in eating disorders. The present study examined factors contributing to excessive intake in a sample of individuals with lifetime eating disorders based on proposed DSM-5 criteria (n = 240) and non-eating disorder controls (n = 157). Individuals with eating disorders, particularly bulimia nervosa, consumed more diet soda than controls. Eating disorder symptoms that reflect increased appetitive drive or increased weight concerns were associated with increased diet soda intake. Increased weight concerns were associated with increased diet soda intake when levels of appetitive drive were high, but not when they were low. Results highlight the importance of monitoring diet soda intake in individuals with eating disorders and may have implications for the maintenance of dysregulated taste reward processing in bulimia nervosa.

Food selection and taste changes in humans after Roux-en-Y gastric bypass surgery: a direct-measures approach

It has been suggested that the weight loss seen in individuals who receive Roux-en-Y gastric bypass surgery may be due, at least in part, to changes in patient food selection, and that this change may stem from effects of the operation on the sense of taste. In this review, we evaluate the literature examining postoperative changes in food intake and food choice. While some evidence suggests that gastric bypass leads to altered food selection and taste perceptions, a clear picture regarding these changes remains to be elucidated and is blurred by inconsistencies, which may be rooted in the diverse subject pools within and between studies as well as in the indirect measures used to assess ingestive behavior. We argue that complementing current assessment tools with more direct measures of intake, food selection, and taste-related behavior might help provide some clarity and also facilitate translation between findings from animal models, in which similar measures are available, and clinical research.

Roux-en-Y gastric bypass in rats increases sucrose taste-related motivated behavior independent of pharmacological GLP-1-receptor modulation

Roux-en-Y gastric bypass (RYGB) surgery has been shown to decrease consummatory responsiveness of rats to high sucrose concentrations, and genetic deletion of glucagon-like peptide-1 receptors (GLP-1R) has been shown to decrease consummatory responsiveness of mice to low-sucrose concentrations. Here we assessed the effects of RYGB and pharmacological GLP-1R modulation on sucrose licking by chow-fed rats in a brief-access test that assessed consummatory and appetitive behaviors. Rats were tested while fasted presurgically and postsurgically and while nondeprived postsurgically and 5 h after intraperitoneal injections with the GLP-1R antagonist exendin-3(9-39) (30 μg/kg), agonist exendin-4 (1 μg/kg), and vehicle in 30-min sessions during which a sucrose concentration series (0.01-1.0 M) was presented in 10-s trials. Other rats were tested postsurgically or 15 min after peptide or vehicle injection while fasted and while nondeprived. Independent of food-deprivation state, sucrose experience, or GLP-1R modulation, RYGB rats took 1.5-3× as many trials as sham-operated rats, indicating increased appetitive behavior. Under nondeprived conditions, RYGB rats with presurgical sucrose experience licked more to sucrose relative to water compared with sham-operated rats. Exendin-4 and exendin-3(9-39) impacted 0.3 M sucrose intake in a one-bottle test, but never interacted with surgical group to affect brief-access responding. Unlike prior reports in both clearly obese and relatively leaner rats given RYGB and in GLP-1R knockout mice, we found that neither RYGB nor GLP-1R blockade decreased consummatory responsiveness to sucrose in our less obese chow-fed rats. Collectively, these results highlight the fact that changes in taste-driven motivated behavior to sucrose after RYGB and/or GLP-1R modulation are very model and measure dependent.