Applying psycho-behavioural phenotyping in obesity characterization

Individual differences in obesity, beyond being explained by metabolic and medical complications, are understood by alterations in eating behaviour which underlie psychological processes. From this psychological perspective, studies have identified several potential characteristic features at the psycho-behavioural level that could additionally explain the maintenance of chronic excess weight or the unsuccessful results of current treatments. To date, despite the growing evidence, the heterogeneity of the psychological evidence associated with obesity has made it challenging to generate consensus on whether these psycho-behavioural phenotypes can be a complement to improve outcomes of existing interventions. For this reason, this narrative review is an overview focused on summarizing studies describing the psycho-behavioural phenotypes associated with obesity. Based on the literature, three psychological constructs have emerged: reward dependence, cognitive control, and mood and emotion. We discuss the clinical implications of stratifying and identifying these psycho-behavioural profiles as potential target for interventions which may ensure a better response to treatment in individuals with obesity. Our conclusions pointed out a considerable overlap between these psycho-behavioural phenotypes suggesting bidirectional interactions between them. These findings endorse the complexity of the psycho-behavioural features associated with obesity and reinforce the need to consider them in order to improve treatment outcomes.

Evaluating the feasibility and exploring the efficacy of an emotion-based approach-avoidance modification training (eAAMT) in the context of perceived stress in an adult sample - protocol of a parallel randomized controlled pilot study

BACKGROUND

Stress levels and thus the risk of developing related physical and mental health conditions are rising worldwide. Dysfunctional beliefs contribute to the development of stress. Potentially, such beliefs can be modified with approach-avoidance modification trainings (AAMT). As previous research indicates that effects of AAMTs are small, there is a need for innovative ways of increasing the efficacy of these interventions. For this purpose, we aim to evaluate the feasibility of the intervention and study design and explore the efficacy of an innovative emotion-based AAMT version (eAAMT) that uses the display of emotions to move stress-inducing beliefs away from and draw stress-reducing beliefs towards oneself.

METHODS

We will conduct a parallel randomized controlled pilot study at the Friedrich-Alexander-Universität Erlangen-Nürnberg, Germany. Individuals with elevated stress levels will be randomized to one of eight study conditions (n = 10 per condition) - one of six variants of the eAAMT, an active control intervention (swipe-based AAMT), or an inactive control condition. Participants in the intervention groups will engage in four sessions of 20-30 min (e)AAMT training on consecutive days. Participants in the inactive control condition will complete the assessments via an online tool. Non-blinded assessments will be taken directly before and after the training and 1 week after training completion. The primary outcome will be perceived stress. Secondary outcomes will be dysfunctional beliefs, symptoms of depression, emotion regulation skills, and physiological stress measures. We will compute effect sizes and conduct mixed ANOVAs to explore differences in change in outcomes between the eAAMT and control conditions.

DISCUSSION

The study will provide valuable information to improve the intervention and study design. Moreover, if shown to be effective, the approach can be used as an automated smartphone-based intervention. Future research needs to identify target groups benefitting from this intervention utilized either as stand-alone treatment or an add-on intervention that is combined with other evidence-based treatments.

TRIAL REGISTRATION

The trial has been registered in the German Clinical Trials Register (Deutsches Register Klinischer Studien; DRKS00023007 ; September 7, 2020).

Concept of Affective Dependence and Validation of an Affective Dependence Scale

Background

There is a degree of affective interdependence that is considered normal and only becomes pathological if it causes excessive suffering, both for the subject and for those close to them. Our objective was to introduce and psychometrically validate a short and effective affective dependency scale, the Affective Dependence Scale (ADS-9).

Methods

We used a sample of 762 participants (clinical: emotional dependent subjects n = 212, comparison: non-emotionally-dependent addicted subjects n = 272, and general population n = 278) to assess the factor structure, the psychological construct validity and the measurement invariance for the ADS-9 by means of independent exploratory factor analyses for each sample group and subsequent multigroup confirmatory factor analyses.

Results

Our results confirm that ADS-9 is a psychometrically consistent instrument, with construct and clinical validity, as well as configural, metric and scalar invariance across different sample groups (clinical, comparison and general population). A hypothesized two-dimensional structure was confirmed by means of factor analyses. Both sub-scales of this abbreviated form, Submission and Craving, showed a good agreement with the previously validated Relationships and Sentimental Dependencies Inventory (IRIDS-100).

Conclusion

The ADS-9 is a brief instrument that appears to reliably detect the dependent and pathological components of affective dependence. It consists of two sub-scales, describing Submission (adaptation, accommodation, and subjugation) and Craving (imperative need for the other with the presence of disturbing states). We suggest that it is a versatile scale that may be useful for clinicians and researchers.

The effects of response inhibition training following binge memory retrieval in young adults binge eaters: a randomised-controlled experimental study

Binge eating is increasingly prevalent among adolescents and young adults and can have a lasting harmful impact on mental and physical health. Mechanistic insights suggest that aberrant reward-learning and biased cognitive processing may be involved in the aetiology of binge eating. We therefore investigated whether recently developed approaches to catalyse brief interventions by putatively updating maladaptive memory could also boost the effects of cognitive bias modification training on binge eating behaviour. A non-treatment-seeking sample of 90 binge eating young adults were evenly randomised to undergo either selective food response inhibition training, or sham training following binge memory reactivation. A third group received training without binge memory reactivation. Laboratory measures of reactivity and biased responses to food cues were assessed pre-post intervention and bingeing behaviour and disordered eating assessed up to 9 months post-intervention. The protocol was pre-registered at https://osf.io/82c4r/ . We found limited evidence of premorbid biased processing in lab-assessed measures of cognitive biases to self-selected images of typical binge foods. Accordingly, there was little evidence of CBM reducing these biases and this was not boosted by prior 'reactivation' of binge food reward memories. No group differences were observed on long-term bingeing behaviour, caloric consumption or disordered eating symptomatology. These findings align with recent studies showing limited impact of selective inhibition training on binge eating and do not permit conclusions regarding the utility of retrieval-dependent memory 'update' mechanisms as a treatment catalyst for response inhibition training.

Too hot to handle: Mood states moderate implicit approach vs. avoidance tendencies toward food cues in patients with obesity and active binge eating disorder

Patients with binge eating disorder (BED) display recurring episodes of eating large amounts of food in a short period of time, especially during negative mood states. However, the psychological processes linking negative mood to binge eating behavior have not been sufficiently explored. This study investigated the effects of experimentally inducing a negative (sad) mood state upon reaction times in a computerized Approach-Avoidance-Task (AAT) using images of foods and compared to a neutral control procedure in which negative mood was not induced. Differences in reaction times between "pulling" and "pushing away" food cues in the AAT were considered surrogates for fast, automatic (i.e., implicit) preferences ("bias") for either the approach or avoidance of foods. Obese patients with BED (n = 40), weight-matched (obese) individuals (n = 40), and norm-weight controls (n = 29) were asked to approach ("pull") or avoid ("push") images of high- and low-calorie foods following the induction of a negative mood state vs. the neutral control procedure. Sample size was within the common range of previous investigations of the kind. Similar to previous findings, obese patients with BED exhibited an avoidance bias (i.e., faster reaction times in "pushing" compared to "pulling") during the neutral control condition. However, a contrast analysis revealed that negative mood was associated with decreased avoidance bias in obese patients with BED, but not in obese and norm-weight controls. Mood status exerted no effect on BED patients' self-reported (i.e., explicit) ratings of the urge to consume foods. These findings may help to advance current understanding of how negative (sad) mood states may affect binge eating behaviors. Implications of these findings for developing novel treatment approaches are discussed.

A dismantling study on imaginal retraining in overweight or obese women

Imaginal retraining is a variant of approach bias modification and transfers the method into one's own mind. As the technique contains multiple elements, this pilot study aimed to dismantle which of its components is most efficient in reducing craving for high-calorie food. A total of 113 women were randomly allocated to one out of six conditions containing a short intervention to mentally manipulate a picture displaying high-calorie foods. Four of the interventions involved different combinations of elements of the imaginal retraining technique, while the remaining two conditions comprised thought suppression or merely observing a picture. Participants rated their level of craving, as well as three pictures containing healthy and unhealthy foods regarding their pleasantness before and after the interventions took place. Within-group changes were assessed with paired t-tests (in case of non-normal data Wilcoxon paired t-tests) and between-group differences with one-way ANOVAs (non-parametric Kruskal-Wallis tests). A trend level reduction in craving was found in the imaginal retraining condition with and without a movement. A post hoc analysis of both conditions joint together showed a statistically significant reduction in craving. In addition, positive picture appraisal for unhealthy foods was significantly reduced in both imaginal retraining conditions (with and without movement) with medium to large effect sizes. This study demonstrated that imaginal retraining with an arm movement can reduce craving and picture appraisal for high-calorie foods significantly in a one-time application. It is a promising technique to reduce appraisal for unhealthy high-calorie foods. Future studies should repeat the experiment in situations of high craving and allow for a personalized selection of stimuli.

Participants' experience of approach bias modification training with transcranial Direct Current Stimulation as a combination treatment for binge eating disorder

OBJECTIVE

This study explored participants' experience of approach bias modification training (ABM) with transcranial Direct Current Stimulation (tDCS) for binge eating disorder (BED) within a randomised controlled trial (RCT). A subset of participants who completed the RCT were interviewed to attain feedback on treatment experience and outcomes.

METHOD

15 participants with BED who completed the RCT were recruited, using purposive sampling. Participants received six sessions of concurrent ABM training with either real or sham tDCS. Semi-structured interviews relating to study experience and treatment outcomes were conducted and data were analysed thematically.

RESULTS

The combined ABM and tDCS intervention was deemed acceptable and worthwhile by participants interviewed across both intervention groups. Negative preconceptions of tDCS were an initial deterrent to study participation for some, yet the brain stimulation experience was found to be tolerable. Minor and transient sensations and side effects attributed to tDCS were reported by most participants during and after stimulation, in addition to less pleasant aspects of ABM training, with no significant adverse effects reported by interviewees. Positive outcomes were described by participants across both intervention groups, relating to changes in BED symptoms and to broader beneficial effects on associated cognitive and emotional factors. Two participants experienced a shift in autonomy, attributed to tDCS and the combined intervention respectively.

CONCLUSIONS

Adults with symptoms of BED found concurrent ABM and tDCS sessions to be acceptable, despite initial apprehension about the safety of tDCS. Findings are relevant to the neuroethics literature and may inform science communication strategies on neuromodulation treatments.

Effects of go/no-go training on food-related action tendencies, liking and choice

Inhibitory control training effects on behaviour (e.g. 'healthier' food choices) can be driven by changes in affective evaluations of trained stimuli, and theoretical models indicate that changes in action tendencies may be a complementary mechanism. In this preregistered study, we investigated the effects of food-specific go/no-go training on action tendencies, liking and impulsive choices in healthy participants. In the training task, energy-dense foods were assigned to one of three conditions: 100% inhibition (no-go), 0% inhibition (go) or 50% inhibition (control). Automatic action tendencies and liking were measured pre- and post-training for each condition. We found that training did not lead to changes in approach bias towards trained foods (go and no-go relative to control), but we warrant caution in interpreting this finding as there are important limitations to consider for the employed approach-avoidance task. There was only anecdotal evidence for an effect on food liking, but there was evidence for contingency learning during training, and participants were on average less likely to choose a no-go food compared to a control food after training. We discuss these findings from both a methodological and theoretical standpoint and propose that the mechanisms of action behind training effects be investigated further.

Implicit bias to food and body cues in eating disorders: a systematic review

BACKGROUND

Rigid, restrictive eating patterns, fear of gaining weight, body image concerns, but also binge eating episodes with loss of control leading to overweight, at times followed by compensatory measures to control weight, are typical symptoms in eating disorders (EDs). The regulation of food intake in EDs may underlie explicit processes that require cognitive insight and conscious control or be steered by implicit mechanisms that are mostly automatic, rapid, and associated with affective-rather than cognitive-processing. While introspection is not capable of assessing implicit responses, so-called indirect experimental tasks can assess implicit responses underlying a specific behavior by-passing the participant's consciousness. Here, we aimed to present the current evidence regarding studies on implicit biases to food and body cues in patients with EDs.

METHODS

We performed a systematic review (PRISMA guidelines). We included controlled studies performed in clinical ED cohorts (vs. healthy control subjects or another control condition, e.g., restrictive vs. binge/purge AN) and using at least one indirect assessment method of interest.

RESULTS

Out of 115 screened publications, we identified 29 studies fulfilling the eligibility criteria, and present a synthesis of the essential findings and future directions.

CONCLUSION

In this emerging field of research, the present work provides cornerstones of evidence highlighting aspects of implicit regulation in eating disorders. Applying both direct (e.g., self-reports) and indirect measures for the assessment of both explicit and implicit responses is necessary for a comprehensive investigation of the interplay between these different regulatory mechanisms and eating behavior. Targeted training of implicit reactions is already in use and represents a useful future tool as an add-on to standard psychotherapeutic treatments in the battle against eating disorders.

EVIDENCE LEVEL

1 (systematic review).

Approach avoidance training to curb consumption of sugar-sweetened beverages - A pilot randomized controlled trial in healthy volunteers

Elevated consumption of sugar-sweetened beverages (SSBs) contributes to overweight and obesity. Automatic action tendencies like an approach bias might promote the consumption of SSBs. We investigated whether an Approach-Avoidance Training (AAT) reduces this approach bias and related behaviors like craving for and consumption of SSBs. Fifty-six healthy participants, with a self-reported SSB consumption of at least 330 ml per day, were randomized to 6 sessions of real or sham AAT. In the real AAT condition, participants were trained to react with avoidance movements to pictures of SSBs in an implicit learning paradigm (i.e. participants were instructed to respond to a task-irrelevant feature), whereas in the sham AAT condition the same pictures were used but no systematic (avoidance) reaction was trained. Approach bias, craving for SSB and SSB intake in a bogus taste test were assessed. Real AAT was not superior to sham AAT in any outcome measure. AAT in its current form and as a stand-alone intervention does not appear to be effective in reducing SSB consumption.

Food approach bias is moderated by the desire to eat specific foods

In a post-scarcity world, energy intake and excesses therein are mediated by psychological mechanisms, such as implicit inclinations to approach certain foods. We investigated how food deprivation, calorie content and individual food preferences affect this approach bias. Sixty women performed a touchscreen-based approach-avoidance task featuring a wide range of food items, once while satiated and once while food-deprived for 15 h. We found an overall approach bias towards food that was not influenced by food deprivation or calorie density of the food items. Instead, we found that approach bias related to the participants' (lack of) desire to eat specific food items, and to a lesser extent to how much their general desire to eat changed due to food deprivation. Links with food preference were selective to trials in which foods had to be approached, and were absent in trials in which foods had to be avoided, pointing to selectivity to appetitive brain systems and clarifying the nature of the bias. Approach bias was unrelated to overall state or trait food craving. We conclude approach bias for appetitive stimuli may primarily express itself as speeded approach rather than slowed avoidance. Additionally, our results show there is merit in personalizing stimulus selection for approach bias measurement and retraining, as approach bias was concordant with individual food preferences, rather than objective calorie content.

A personalized approach-avoidance modification intervention to reduce negative body image. A placebo-controlled pilot study

BACKGROUND AND OBJECTIVES

Drive for thinness is considered an important factor in the onset and maintenance of negative body image and can be conceptualized as a motivational approach tendency towards thin bodies. The goal of this study was to test whether training thinness-related approach-avoidance tendencies is effective in improving body satisfaction using a personalized training with individuals' own body pictures.

METHODS

Undergraduate women scoring high on drive for thinness (N = 104) were randomly assigned to an experimental, placebo or no training control condition. The experimental training consisted of four training sessions in which participants pushed away thin versions of their own body pictures and pulled closer realistic pictures of themselves. The same stimuli were shown with 50/50 contingency in the placebo training.

RESULTS

The experimental training procedure did not show an effect on self-reported body satisfaction or drive for thinness after one session, four sessions, or one week later. While reaction time indices suggested a marginally significant change in approach-avoidance tendencies in the expected direction, this effect may have been driven by relatively strong thin-approach tendencies in the experimental condition before the start of the training.

LIMITATIONS

High error rates limit the interpretability of the effects on approach-avoidance tendencies. Selection was based on a single item assessing drive for thinness.

CONCLUSIONS

Taken together, our study did not provide evidence that training approach-avoidance tendencies is effective in improving negative body image.

Laboratory-based interventions targeting food craving: A systematic review and meta-analysis

This systematic review and meta-analysis aimed to quantify the effects of laboratory-based interventions targeting specific mechanisms of food craving, to identify moderators of effects, and to qualitatively summarize findings. The study was conducted and reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Sixty-nine studies were included in the quantitative synthesis, and separate meta-analyses were conducted for the outcomes self-reported craving and objective food intake. Results show small to medium positive effects across specific craving interventions on both outcomes. Effect sizes were partly moderated by intervention type. The most effective intervention regarding food intake was in sensu cue exposure. For subjective craving, the most robust evidence was found for beneficial effects of cognitive regulation strategies (ie, reappraisal, suppression, and distraction). Results further indicate that training inhibitory control through behavioral inhibition might be more effective than approach-avoidance training when considering its effect on subjective craving and food intake. People with external eating habits, overeating, or loss-of-control eating might benefit from these types of specific craving interventions. Future research should focus on long-term effects, transferability, and effectiveness in clinical samples.

Approach bias modification training to increase physical activity: A pilot randomized controlled trial in healthy volunteers

Regular physical activity is associated with better physical and mental health outcomes as well as higher quality of life. This pilot randomized controlled trial examined whether approach bias modification, an economical and easily accessible computerized cognitive training, could increase objectively and subjectively measured physical activity in individuals aiming for more physical activity. Forty healthy volunteers of normal weight were randomly allocated to six sessions of approach bias modification or no treatment. The approach bias modification adopted an implicit learning paradigm that trained participants to show approach behavior in response to visual cues of physical activity. Approach bias modification did not increase objectively and subjectively measured physical activity.

Twenty Years of the Food Cravings Questionnaires: a Comprehensive Review

Purpose of Review

The Food Cravings Questionnaires (FCQs; Cepeda-Benito, Gleaves, Williams, & Erath, 2000) are among the most widely used instruments for measuring food cravings. In addition to the Food Cravings Questionnaire–Trait (FCQ–T) and the Food Cravings Questionnaire–State (FCQ–S), several modified versions have been developed as well. For their 20th anniversary, this article provides a comprehensive description of the FCQs and reviews studies on their psychometric properties and correlates.

Recent Findings

The FCQs and their modified versions have excellent internal reliability. Expectedly, the FCQ–T (and its derivatives) has higher retest-reliability than the FCQ–S as the FCQ–S is sensitive to situational changes such as food deprivation and food intake. However, while the FCQ–T is largely unaffected by such momentary states, it is also sensitive to change during weight-loss treatments and other interventions. Factor structure of the FCQ–T and FCQ–S has only partially been replicated. Construct validity of the FCQs is supported by experimental and longitudinal studies that measured food craving and food consumption in the laboratory and with ecological momentary assessment.

Summary

Numerous studies support reliability and validity of the FCQs and their modified versions, yet findings about their factor structures are inconsistent. Thus, using total scores or the short versions of the FCQs may be preferable.

Study protocol of a randomised controlled feasibility study of food-related computerised attention training versus mindfulness training and waiting-list control for adults with overweight or obesity

Background

Obesity is a highly prevalent condition with multiple adverse health consequences. Widely available first-line treatments for obesity, such as dietary and other lifestyle interventions, typically have only short-term effects. Thus, new treatment approaches are needed. Novel interventions such as Attention Bias Modification Training (ABMT) and mindfulness-based interventions focus on modifying different maladaptive cognitive patterns typically present in people with obesity (e.g. attention bias to food cues); however, their mechanisms of action remain largely unknown. We describe the theoretical basis and the rationale for a study protocol of a feasibility randomised controlled trial (RCT) comparing two attention trainings (ABMT vs Mindfulness Training [MT]) in people with overweight or obesity. The aim of this study is to inform the development of a large-scale RCT in relation to acceptability and attendance rates and to identify preliminary evidence for the interventions’ clinical efficacy and potential underlying mechanisms.

Design

Forty-five adults who are either overweight or obese (minimum body mass index of 25 kg/m²) will be randomly allocated to receive eight sessions over eight weeks of either computerised ABMT or MT or be on a waiting list. Clinical and cognitive outcomes will be assessed at baseline, post-treatment (8 weeks) and follow-up (12 weeks post-randomisation). These include mood, body composition and attention biases. Credibility and acceptability of the trainings will be assessed using questionnaires, and recruitment and retention rates will be recorded.

Discussion

Findings will inform the feasibility of developing a large-scale RCT that takes into consideration effect sizes for primary outcome measures and the acceptability of the design. The study will also provide preliminary evidence on the clinical efficacy of two different attention trainings for people with obesity and associated underlying mechanisms.

Trial registration

ISRCTN Registry, ISRCTN15745838. Registered on 22 May 2018. 

Effects of a Smartphone-Based Approach-Avoidance Intervention on Chocolate Craving and Consumption: Randomized Controlled Trial

BACKGROUND

Repeatedly pushing high-calorie food stimuli away based on joystick movements has been found to reduce approach biases toward these stimuli. Some studies also found that such avoidance training reduced consumption of high-calorie foods.

OBJECTIVE

This study aimed to test effects of a smartphone-based approach-avoidance intervention on chocolate craving and consumption, to make such interventions suitable for daily use.

METHODS

Within a 10-day period, regular chocolate eaters (n=105, 86% female) performed five sessions during which they continuously avoided (ie, swiped upward) chocolate stimuli (experimental group, n=35), performed five sessions during which they approached and avoided chocolate stimuli equally often (placebo control group, n=35), or did not perform any training sessions (inactive control group, n=35). Training effects were measured during laboratory sessions before and after the intervention period and further continuously through daily ecological momentary assessment.

RESULTS

Self-reported chocolate craving and consumption as well as body fat mass significantly decreased from pre- to postmeasurement across all groups. Ecological momentary assessment reports evidenced no differences in chocolate craving and consumption between intervention days and rest days as a function of the group.

CONCLUSIONS

A smartphone-based approach-avoidance training did not affect eating-related and anthropometric measures over and above measurement-based changes in this study. Future controlled studies need to examine whether other techniques of modifying food approach tendencies show an add-on benefit over conventional, monitoring-based intervention effects.

TRIAL REGISTRATION

AsPredicted 8203; https://aspredicted.org/pt9df.pdf.

Combining cognitive bias modification training (CBM) and transcranial direct current stimulation (tDCS) to treat binge eating disorder: study protocol of a randomised controlled feasibility trial

INTRODUCTION

Binge eating disorder (BED) is a common mental disorder, closely associated with obesity. Existing treatments are only moderately effective with high relapse rates, necessitating novel interventions. This paper describes the rationale for, and protocol of, a feasibility randomised controlled trial (RCT), evaluating the combination of transcranial direct current stimulation (tDCS) and a computerised cognitive training, namely approach bias modification training (ABM), in patients with BED who are overweight or obese. The aim of this trial is to obtain information that will guide decision-making and protocol development in relation to a future large-scale RCT of combined tDCS+ABM treatment in this group of patients, and also to assess the preliminary efficacy of this intervention.

METHODS AND ANALYSIS

66 participants with Diagnostic and Statistical Manual-5 diagnosis of BED and a body mass index (BMI) of ≥25 kg/m2 will be randomly allocated to one of three groups: ABM+real tDCS; ABM+sham tDCS or a wait-list control group. Participants in both intervention groups will receive six sessions of ABM+real/sham tDCS over 3 weeks; engaging in the ABM task while simultaneously receiving bilateral tDCS to the dorsolateral prefrontal cortex. ABM is based on an implicit learning paradigm in which participants are trained to enact an avoidance behaviour in response to visual food cues. Assessments will be conducted at baseline, post-treatment (3 weeks) and follow-up (7 weeks post-randomisation). Feasibility outcomes assess recruitment and retention rates, acceptability of random allocation, blinding success (allocation concealment), completion of treatment sessions and research assessments. Other outcomes include eating disorder psychopathology and related neurocognitive outcomes (ie, delay of gratification and inhibitory control), BMI, other psychopathology (ie, mood), approach bias towards food and surrogate endpoints (ie, food cue reactivity, trait food craving and food intake).

ETHICS AND DISSEMINATION

This study has been approved by the North West-Liverpool East Research Ethics Committee. Results will be published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN35717198.

Food Addiction: Implications for the Diagnosis and Treatment of Overeating

With the obesity epidemic being largely attributed to overeating, much research has been aimed at understanding the psychological causes of overeating and using this knowledge to develop targeted interventions. Here, we review this literature under a model of food addiction and present evidence according to the fifth edition of the Diagnostic and Statistical Manual (DSM-5) criteria for substance use disorders. We review several innovative treatments related to a food addiction model ranging from cognitive intervention tasks to neuromodulation techniques. We conclude that there is evidence to suggest that, for some individuals, food can induce addictive-type behaviours similar to those seen with other addictive substances. However, with several DSM-5 criteria having limited application to overeating, the term 'food addiction' is likely to apply only in a minority of cases. Nevertheless, research investigating the underlying psychological causes of overeating within the context of food addiction has led to some novel and potentially effective interventions. Understanding the similarities and differences between the addictive characteristics of food and illicit substances should prove fruitful in further developing these interventions.

Approach bias modification training in bulimia nervosa and binge-eating disorder: A pilot randomized controlled trial

OBJECTIVE

Bulimia nervosa (BN) and binge-eating disorder (BED) are associated with poorly controlled approach behavior toward food resulting in binge eating. Approach bias modification (ABM) may reduce these automatic action tendencies (i.e., approach bias) toward food and may thus decrease binge eating and related symptoms.

METHOD

A total of 56 patients with BN/BED participated in this double-blind, randomized controlled trial (RCT) comparing real and sham ABM. The real ABM condition adopted an implicit learning paradigm in which participants were trained to show avoidance behavior in response to food cues. Participants in the sham condition used a similar task but were not trained to avoid food cues. Both conditions comprised 10 training sessions within 4 weeks.

RESULTS

Participants in both groups experienced significant reductions in binge eating, eating disorder symptoms, trait food craving, and food cue reactivity. Real ABM tended to result in greater reductions in eating disorder symptoms than sham ABM. Food intake, approach bias, and attention bias toward food did not change.

DISCUSSION

This is the first RCT on ABM in eating disorders. The findings provide limited support for the efficacy of ABM in BN/BED and pose questions regarding its active ingredients and its usefulness as a stand-alone treatment for eating disorders.

Polarity Specific Effects of Cross-Hemispheric tDCS Coupled With Approach-Avoidance Training on Chocolate Craving

Transcranial Direct Current Stimulation (tDCS) over the Dorsolateral Prefrontal Cortex (DLPFC) has already been shown to decrease craving for food. However, it remains unclear whether a single session of tDCS combined with a cognitive bias modification (CBM) task may affect explicit and implicit measures of craving for chocolate. Fifty-one healthy volunteers (38 females; mean age: 22.12 ± 3.38) were randomly allocated to CBM training based on the Approach Avoidance task and either Sham, Right anodal-Left cathodal (RALC), or Left anodal-Right cathodal (LARC) tDCS. Results show that there was an increase in the explicit craving for chocolate, as assessed by the Visual Analog Scale [F(2, 46) = 3.239, p = 0.048], from the baseline to post-intervention. Participants which received LARC tDCS were explicitly self-reporting more craving for chocolate than those that received RALC tDCS (p = 0.023). Moreover, this effect was also observed on the implicit measure [F(2, 46) = 4.168, p = 0.022]. LARC tDCS significantly increased the implicit preference for chocolate when comparing to both RALC (p = 0.009) and Sham tDCS (p = 0.034). Previous studies have shown that RALC tDCS over the PFC is able to effectively decrease craving for food. Interestingly, the present data not only does not reproduce such result, but instead it suggests that LARC tDCS can actually increase the preference for chocolate. This result is compatible with recent models of brain laterality, in which cue craving seems to be more dependent on the left hemisphere. Thus, shifting the activity to the left hemisphere (while simultaneously reducing the activity over the homotopic region) may have led to this increased implicit as well as explicit preference for chocolate.

Suppressing images of desire: Neural correlates of chocolate-related thoughts in high and low trait chocolate cravers

Chocolate is the most often craved food in Western societies and many individuals try to resist its temptation due to weight concerns. Suppressing chocolate-related thoughts might, however, lead to paradoxical enhancements of these thoughts and this effect might be more pronounced in individuals with frequent chocolate cravings. In the current study, neural and cognitive correlates of chocolate thought suppression were investigated as a function of trait chocolate craving. Specifically, 20 high and 20 low trait chocolate cravers followed suppression vs. free thinking instructions after being exposed to chocolate and neutral images. Enhanced cue reactivity was evident in high trait chocolate cravers in that they reported more chocolate-related thoughts selectively after chocolate images compared to their low trait craving counterparts. This cue reactivity was mirrored neurally by higher activation in the ventral and dorsal striatum, demonstrating enhanced reward system activity. Unexpectedly, high trait chocolate cravers successfully reduced their elevated chocolate thoughts in the suppression condition. This lends support for the use of thought suppression as a means of regulating unwanted thoughts, cravings and imagery. Whether this thought manipulation is able to curb the elevated cue reactivity and the underlying reward sensitivity in chocolate cravers in applied settings remains to be shown.

Evaluation of an approach-avoidance training intervention for children and adolescents with obesity: A randomized placebo-controlled prospective trial

This study evaluated the efficacy of approach-avoidance training as an additional treatment for children and adolescents with obesity seeking inpatient treatment. Two hundred thirty-two participants (8-16 years, 53.9% girls) were randomly assigned either to multisession approach-avoidance (IG) or to placebo training (CG). As outcomes, cognitive biases post intervention, body mass index, eating behaviour, food intake, self-regulation, and weight-related quality of life were assessed, also at 6- and 12-month follow-up. Modification of approach-avoidance bias was observed, but lacked in transfer over sessions and in generalization to attention and association bias. After 6 months, the IG reported less "problematic" food consumption, higher self-regulation, and higher quality of life; effects did not persist until the 12-month follow-up; no significant interaction effects were observed regarding weight course. Despite there was no direct effect on weight course, approach-avoidance training seems to be associated with promising effects on important pillars for weight loss. Further research concerning clinical effectiveness is warranted.

Targeting self-regulation to promote health behaviors in children

Poor self-regulation (i.e., inability to harness cognitive, emotional, motivational resources to achieve goals) is hypothesized to contribute to unhealthy behaviors across the lifespan. Enhancing early self-regulation may increase positive health outcomes. Obesity is a major public health concern with early-emerging precursors related to self-regulation; it is therefore a good model for understanding self-regulation and health behavior. Preadolescence is a transition when children increase autonomy in health behaviors (e.g., eating, exercise habits), many of which involve self-regulation. This paper presents the scientific rationale for examining self-regulation mechanisms that are hypothesized to relate to health behaviors, specifically obesogenic eating, that have not been examined in children. We describe novel intervention protocols designed to enhance self-regulation skills, specifically executive functioning, emotion regulation, future-oriented thinking, and approach bias. Interventions are delivered via home visits. Assays of self-regulation and obesogenic eating behaviors using behavioral tasks and self-reports are implemented and evaluated to determine feasibility and psychometrics and to test intervention effects. Participants are low-income 9-12 year-old children who have been phenotyped for self-regulation, stress, eating behavior and adiposity through early childhood. Study goals are to examine intervention effects on self-regulation and whether change in self-regulation improves obesogenic eating.

Battle of plates: a pilot study of an approach–avoidance training for overweight children and adolescents

Objective

Approach–avoidance training (AAT) is a promising approach in obesity treatment. The present study examines whether an AAT is feasible and able to influence approach tendencies in children and adolescents, comparing implicit and explicit training approaches.

Design/Setting/Subjects

Fifty-nine overweight children and adolescents (aged 8–16 years; twenty-six boys) participated in an AAT for food cues, learning to reject snack items and approach vegetable items. Reaction times in the AAT and an implicit association test (IAT) were assessed pre- and post-intervention.

Results

A significant increase in the AAT compatibility scores with a large effect (η2=0·18) was found. No differences between the implicit and explicit training approaches and no change in the IAT scores were observed.

Conclusions

Automatic tendencies in children can be trained, too. The implementation of AAT in the treatment of obesity might support the modification of an unhealthy nutrition behaviour pattern. Further data from randomized controlled clinical trials are needed.

A Randomised Controlled Comparison of Second-Level Treatment Approaches for Treatment-Resistant Adults with Bulimia Nervosa and Binge Eating Disorder: Assessing the Benefits of Virtual Reality Cue Exposure Therapy

A question that arises from the literature on therapy is whether second-level treatment is effective for patients with recurrent binge eating who fail first-level treatment. It has been shown that subjects who do not stop binge eating after an initial structured cognitive-behavioural treatment (CBT) programme benefit from additional CBT (A-CBT) sessions; however, it has been suggested that these resistant patients would benefit even more from cue exposure therapy (CET) targeting features associated with poor response (e.g. urge to binge in response to a cue and anxiety experienced in the presence of binge-related cues). We assessed the effectiveness of virtual reality-CET as a second-level treatment strategy for 64 patients with bulimia nervosa and binge eating disorder who had been treated with limited results after using a structured CBT programme, in comparison with A-CBT. The significant differences observed between the two groups at post-treatment in dimensional (behavioural and attitudinal features, anxiety, food craving) and categorical (abstinence rates) outcomes highlighted the superiority of virtual reality-CET over A-CBT. Copyright © 2017 John Wiley & Sons, Ltd and Eating Disorders Association.

The effect of combined avoidance and control training on implicit food evaluation and choice

BACKGROUND

Continual exposure to food cues in the environment contributes to unhealthy eating behaviour. According to dual-process models, such behaviour is partly determined by automatic processing of unhealthy food cues (e.g., approach bias), which fails to be regulated by controlled processing (e.g., inhibitory control). The current study aimed to investigate the effect of combined avoidance and control training on implicit evaluation (liking), choice, and consumption of unhealthy snack food.

METHOD

Participants were 240 undergraduate women who were randomly allocated to one of four experimental conditions of a 2 (avoidance training: training versus control) x 2 (control training: training versus control) between-subjects design.

RESULTS

The combined training group had a more negative implicit evaluation of unhealthy food than either of the two training conditions alone or the control condition. In addition, participants trained to avoid unhealthy food cues subsequently made fewer unhealthy snack food choices. No significant group differences were found for food intake.

LIMITATIONS

Participants were women generally of a healthy weight. Overweight or obese individuals may derive greater benefit from combined training.

CONCLUSIONS

Results lend support to the theoretical predictions of dual-process models, as the combined training reduced implicit liking of unhealthy food. At a practical level, the findings have implications for the effectiveness of interventions targeting unhealthy eating behaviour.

Cognitive training as a potential treatment for overweight and obesity: A critical review of the evidence

The aim of this review is to critically evaluate the effectiveness and candidate mechanisms of action of psychological interventions which aim to either (a) improve the capacity for self-regulatory, reflective processes or (b) reduce the impact of automatic appetitive processes, in an attempt to influence food intake and associated weight-gain. Our aim was to examine three important issues regarding each type of intervention: i) whether the intervention influenced behaviour in the laboratory, ii) whether the intervention influenced behaviour and/or body mass index in the real world, and iii) whether the proposed mechanism of action was supported by evidence. We systematically searched three commonly used databases and identified 32 articles which were relevant to at least one of these issues. The majority of studies attempted to manipulate food intake in the laboratory using associative learning paradigms, in normal-weight female participants. Most of the laboratory studies demonstrated the predicted effects of interventions on behaviour in the laboratory, but studies that attempted to translate these interventions outside of the laboratory yielded more mixed findings. The hypothesised mechanisms of action received inconsistent support across studies. We identified several limitations which may complicate interpretation of findings in this area, including heterogeneity of study methods, small sample sizes, and absence of adequate control groups. We provide recommendations for future studies that aim to develop and evaluate these promising interventions for the reduction of overweight and obesity.

Food cravings in everyday life: An EMA study on snack-related thoughts, cravings, and consumption

Food craving refers to an intense desire to consume a specific food and is regularly experienced by the majority of individuals. Yet, there are interindividual differences in the frequency and intensity of food craving experiences, which is often referred to as trait food craving. The characteristics and consequences of trait and state food craving have mainly been investigated in questionnaire-based and laboratory studies, which may not reflect individuals' behavior in daily life. In the present study, sixty-one participants completed the Food Cravings Questionnaire-Trait-reduced (FCQ-T-r) as measure of trait food craving, followed by seven days of Ecological Momentary Assessment (EMA), during which they reported snack-related thoughts, craving intensity, and snack consumption at five times per day. Results showed that 86 percent of reported snacks were high-caloric, with chocolate-containing foods being the most often reported snacks. Individuals with high FCQ-T-r scores (high trait food cravers, HCs) thought more often about high-calorie than low-calorie snacks whereas no differences were found in individuals with low FCQ-T-r scores (low trait food cravers, LCs). Further, the relationship between craving intensity and snack-related thoughts was stronger in HCs than in LCs. Higher craving intensity was associated with more consumption of snacks and again this relationship was stronger in HCs than in LCs. Finally, more snack-related thoughts were related to more frequent consumption of snacks, independent of trait food craving. Thus, HCs are more prone to think about high-calorie snacks in their daily lives and to consume more snack foods when they experience intense cravings, which might be indicative of a heightened responding towards high-calorie foods. Thus, trait-level differences as well as snack-related thoughts should be targeted in dietary interventions.

Approach bias modification training and consumption: A review of the literature

Recent theoretical perspectives and empirical evidence have suggested that biased cognitive processing is an important contributor to unhealthy behaviour. Approach bias modification is a novel intervention in which approach biases for appetitive cues are modified. The current review of the literature aimed to evaluate the effectiveness of modifying approach bias for harmful consumption behaviours, including alcohol use, cigarette smoking, and unhealthy eating. Relevant publications were identified through a search of four electronic databases (PsycINFO, Google Scholar, ScienceDirect and Scopus) that were conducted between October and December 2015. Eligibility criteria included the use of a human adult sample, at least one session of avoidance training, and an outcome measure related to the behaviour of interest. The fifteen identified publications (comprising 18 individual studies) were coded on a number of characteristics, including consumption behaviour, participants, task, training and control conditions, number of training sessions and trials, outcome measure, and results. The results generally showed positive effects of approach-avoidance training, including reduced consumption behaviour in the laboratory, lower relapse rates, and improvements in self-reported measures of behaviour. Importantly, all studies (with one exception) that reported favourable consumption outcomes also demonstrated successful reduction of the approach bias for appetitive cues. Thus, the current review concluded that approach bias modification is effective for reducing both approach bias and unhealthy consumption behaviour.

The ABBA study - approach bias modification in bulimia nervosa and binge eating disorder: study protocol for a randomised controlled trial

BACKGROUND

The core symptoms of bulimia nervosa (BN) and binge eating disorder (BED) are recurrent episodes of binge eating. Despite negative psychological and physical consequences, BN/BED patients show uncontrollable approach tendencies towards food. This cognitive bias occurs at an early stage of information processing. Cognitive bias modification (CBM) directly targets such biases and has been shown to be effective in treating several mental disorders. In alcohol addiction, automatic action tendencies towards alcohol cues and relapse rates were successfully reduced by a specific form of CBM, termed approach bias modification. Based on these findings and data from a proof-of-concept study in people with high levels of food craving, CBM is considered a promising new treatment approach for BN/BED. Given the similarities between BN/BED and addictive disorders, the rationale for using approach bias modification appears to be particularly strong. The aim of the present study is to examine whether, compared to a sham training, computerised approach bias modification (10 sessions) can reduce binge-eating episodes in BN/BED patients from pre-treatment to follow-up. Additionally, we will investigate whether this CBM programme also reduces global eating disorder psychopathology, trait and cue-elicited food craving, food intake as well as approach and attentional bias towards visual food cues. Treatment acceptance will be determined by attrition rates and responses on a feedback form.

METHODS

This is a double-blind, randomised, placebo-controlled, parallel-group superiority trial with two parallel arms. A total of 54 BN/BED patients will be recruited. Approach bias towards food will be retrained by a computer task adopting an implicit learning paradigm. Patients in the control condition (sham) will conduct a similar task but will not be trained to avoid food cues. Methods against bias include public registration, randomisation by a central study office, standardisation of the treatments and blinding of assessors. Furthermore, the session number and duration will be equivalent in the two conditions.

DISCUSSION

This is the first registered randomised controlled trial of approach bias modification in a clinical BN/BED sample. Results from this study will provide an indication of the efficacy of approach bias modification training for BN/BED and the potential mechanisms of action underlying this treatment.

TRIAL REGISTRATION

DRKS00010231 (retrospectively registered on 24 March 2016; first version).

Crave, Like, Eat: Determinants of Food Intake in a Sample of Children and Adolescents with a Wide Range in Body Mass

Obesity is a heterogeneous condition with obese individuals displaying different eating patterns. Growing evidence suggests that there is a subgroup of obese adults that is marked by frequent and intense food cravings and addiction-like consumption of high-calorie foods. Little is known, however, about such a subgroup of obese individuals in childhood and adolescence. In the present study, a sample of children and adolescents with a wide range in body mass was investigated and trait food craving, liking for and intake of high- and low-calorie foods was measured. One-hundred and forty-two children and adolescents (51.4% female, n = 73; Mage = 13.7 years, SD = 2.25; MBMI-SDS = 1.26, SD = 1.50) completed the Food Cravings Questionnaire-Trait, then viewed pictures of high- and low-calorie foods and rated their liking for them, and subsequently consumed some of these foods in a bogus taste test. Contrary to expectations, higher body mass was associated with lower consumption of high-calorie foods. However, there was an interaction between body mass and trait food craving when predicting food consumption: in obese participants, higher trait food craving was associated with higher consumption of high-calorie foods and this association was not found in normal-weight participants. The relationship between trait food craving and high-calorie food consumption within obese individuals was mediated by higher liking for high-calorie foods (but not by liking for low-calorie foods). Thus, similar to adults, a subgroup of obese children and adolescents - characterized by high trait food craving - seems to exist, calling for specific targeted treatment strategies.

An open trial evaluating an attention bias modification program for overweight adults who binge eat

BACKGROUND AND OBJECTIVES

Binge eating is prevalent and is associated with significant psychiatric and medical comorbidities. To date, the most effective psychological treatments for individuals who binge eat are not effective for all patients and they do not result in significant weight loss. Dual process theories suggest that implicit factors, such as attention bias, may influence behavior, even when the behavior is in opposition to long-term goals. Attention bias modification programs have been tested in other areas of psychopathology, and could be utilized to improve outcomes for people who binge eat. Thus, the aim of this open trial was to conduct a preliminary evaluation of an attention bias modification program (ABM-Food) designed to train attention away from food cues.

METHODS

Adults who binge eat and were overweight or obese enrolled in an 8-week ABM-Food program, which consisted of one session in the lab each week and two training sessions at home. Nine participants completed the ABM-Food training program and the post-treatment assessment, and 8 completed the 3-month post-treatment assessment.

RESULTS

Results showed that the ABM-Food program is a feasible and acceptable treatment for adults who binge eat. Initial effectiveness data showed decreases in weight, eating disorder symptoms, binge eating, loss of control and responsivity to food in the environment, as well as changes in attention bias. The majority of these effects remained at the 3-month follow-up time point.

LIMITATIONS

This study is limited by the single-group open label trial, and the small sample size.

CONCLUSIONS

This open trial provides initial evidence for the feasibility, acceptability and effectiveness of ABM-Food for individuals who binge eat and are overweight or obese.

Task-Based and Questionnaire Measures of Inhibitory Control Are Differentially Affected by Acute Food Restriction and by Motivationally Salient Food Stimuli in Healthy Adults

Adaptive eating behaviors are dependent on an interaction between motivational states (e.g., hunger) and the ability to control one's own behavior (inhibitory control). Indeed, behavioral paradigms are emerging that seek to train inhibitory control to improve eating behavior. However, inhibitory control is a multifaceted concept, and it is not yet clear how different types (e.g., reactive motor inhibition, proactive motor inhibition, reward-related inhibition) are affected by hunger. Such knowledge will provide insight into the contexts in which behavioral training paradigms would be most effective. The present study explored the impact of promoting a "need" state (hunger) together with motivationally salient distracting stimuli (food/non-food images) on inhibitory control in 46 healthy adults. Participants attended two study sessions, once after eating breakfast as usual and once after acute food restriction on the morning of the session. In each session, participants completed questionnaires on hunger, mood and inhibitory control, and undertook task-based measures of inhibitory control, and had physiological measurements (height, weight, and blood glucose) obtained by a researcher. Acute food restriction influenced task-based assessments but not questionnaire measures of inhibitory control, suggesting that hunger affects observable behavioral control but not self-reported inhibitory control. After acute food restriction, participants showed greater temporal discounting (devaluation of future rewards), and subjective hunger and these were inversely correlated with stop accuracy on the stop signal task. Finally, participants generally responded faster when food-related distractor images were presented, compared to non-food images, independent of state. This suggests that although food stimuli motivate approach behavior, stimulus relevance does not impact inhibitory control in healthy individuals, nor interact with motivational state. These findings may provide some explanation for poorer inhibitory control often reported in studies of individuals who practice restraint over eating.

Alleged Approach-Avoidance Conflict for Food Stimuli in Binge Eating Disorder

OBJECTIVE

Food stimuli are omnipresent and naturally primary reinforcing stimuli. One explanation for the intake of high amounts of food in binge eating disorder (BED) is a deviant valuation process. Valuation of food stimuli is supposed to influence approach or avoidance behaviour towards food. Focusing on self-reported and indirect (facial electromyography) valuation process, motivational aspects in the processing of food stimuli were investigated.

METHODS

We compared an overweight sample with BED (BED+) with an overweight sample without BED (BED-) and with normal weight controls (NWC) regarding their self-reported and indirect (via facial electromyography) valuation of food versus non-food stimuli.

RESULTS

Regarding the self-reported valuation, the BED+ sample showed a significantly stronger food-bias compared to the BED- sample, as food stimuli were rated as significantly more positive than the non-food stimuli in the BED+ sample. This self-reported valuation pattern could not be displayed in the indirect valuation. Food stimuli evoked negative indirect valuation in all groups. The BED+ sample showed the plainest approach-avoidance conflict marked by a diverging self-reported (positive) and indirect (negative) valuation of food stimuli.

CONCLUSIONS

BED+ showed a deviant self-reported valuation of food as compared to BED-. The valuation process of the BED+ sample seems to be characterized by a motivational ambivalence. This ambivalence should be subject of further studies and may be of potential use for therapeutic interventions.