Savani Bartholdy

A systematic review of the relationship between eating, weight and inhibitory control using the stop signal task.

Altered inhibitory control (response inhibition, reward-based inhibition, cognitive inhibition, reversal learning) has been implicated in eating disorders (EDs) and obesity. It is unclear, however, how different types of inhibitory control contribute to eating and weight-control behaviours. This review evaluates the relationship between one aspect of inhibitory control (a reactive component of motor response inhibition measured by the stop signal task) and eating/weight in clinical and non-clinical populations. Sixty-two studies from 58 journal articles were included. Restrained eaters had diminished reactive inhibitory control compared to unrestrained eaters, and showed greatest benefit to their eating behaviour from manipulations of inhibitory control. Obese individuals may show less reactive inhibitory control but only in the context of food-specific inhibition or after executive resources are depleted. Of the limited studies in EDs, the majority found no impairment in reactive inhibitory control, although findings are inconsistent. Thus, altered reactive inhibitory control is related to some maladaptive eating behaviours, and hence may provide a therapeutic target for behavioural manipulations and/or neuromodulation. However, other types of inhibitory control may also contribute. Methodological and theoretical considerations are discussed.

The Potential of Neurofeedback in the Treatment of Eating Disorders: A Review of the Literature

Neurofeedback is defined as the training of voluntary regulation of localised neural activity using real-time feedback through a brain-computer interface. It has shown initial success as a potential clinical treatment tool in proof of concept studies, but has yet to be evaluated with respect to eating disorders. This paper (i) provides a brief overview of the current status of eating disorder treatments; (ii) describes the studies to date that use neurofeedback involving electroencephalography, real-time functional magnetic resonance imaging or near-infrared spectroscopy; and (iii) considers the potential of these technologies as treatments for eating disorders.

A systematic review of temporal discounting in eating disorders and obesity: Behavioural and neuroimaging findings.

OBJECTIVE Eating Disorders (ED) and obesity are suggested to involve a spectrum of self-regulatory control difficulties. Temporal discounting (TD) tasks have been used to explore this idea. This systematic review examines behavioural and neuroimaging TD data in ED and obesity. METHOD Using PRISMA guidelines, we reviewed relevant articles in MEDLINE, PsycINFO and Embase from inception until 17th August 2016. Studies that reported behavioural differences in TD and/or TD neuroimaging data in ED/obesity were included. RESULTS Thirty-one studies were included. Limited data suggest that BN, BED and obesity are associated with increased TD, whilst data in AN are mixed. Aberrant neural activity in frontostriatal circuitry is implicated. TD tasks vary widely and TD in ED/obesity may vary according to factors such as illness stage. CONCLUSION Our findings suggest altered self-regulatory control in ED and obesity. TD tasks are heterogeneous, limiting generalisability of findings. Research into whether TD is multidimensional, along with transdiagnostic neuroimaging research is needed. Assessment of TD may be useful in psychoeducation, outcome prediction and treatment of ED/obesity.

Increased temporal discounting in bulimia nervosa.

OBJECTIVE There is evidence that people with eating disorders display altered intertemporal choice behavior (the degree of preference for immediate rewards over delayed rewards). Compared to healthy controls (HC), individuals with anorexia nervosa and binge-eating disorder show decreased and increased rates of temporal discounting (TD; the devaluation of delayed rewards), respectively. This is the first study to investigate TD in people with bulimia nervosa (BN). METHOD Thirty-nine individuals with BN (2 men) and 53 HC (9 men) completed a hypothetical monetary TD task. Over 80 binary choices, participants chose whether they would prefer to receive a smaller amount of money available immediately or a larger amount available in 3 months. Self-reported ability to delay gratification (the behavioral opposite of TD) was also measured. RESULTS Individuals with BN showed greater TD (i.e., a preference for smaller-sooner rewards) and a decreased self-reported capacity to delay gratification relative to HC. Experimental groups did not differ in age, gender ratio, or BMI. DISCUSSION Increased rates of TD may contribute to some of the core symptoms of BN that appear to involve making choices between immediate and delayed rewards (i.e., binge-eating and compensatory behaviors). Altered intertemporal choice behavior could therefore be a relevant target for intervention in this patient group.

Two-year follow-up of the MOSAIC trial: A multicenter randomized controlled trial comparing two psychological treatments in adult outpatients with broadly defined anorexia nervosa.

OBJECTIVE This study reports follow-up data from a multicenter randomized controlled trial (n = 142) comparing the Maudsley Model of Anorexia Nervosa Treatment for Adults (MANTRA) with Specialist Supportive Clinical Management (SSCM) in outpatients with broadly defined anorexia nervosa (AN). At 12 months postrandomization, all patients had statistically significant improvements in body mass index (BMI), eating disorder (ED) symptomatology and other outcomes with no differences between groups. MANTRA was more acceptable to patients. The present study assessed whether gains were maintained at 24 months postrandomization. METHODS Follow-up data at 24 months were obtained from 73.2% of participants. Outcome measures included BMI, ED symptomatology, distress, impairment, and additional service utilization during the study period. Outcomes were analyzed using linear mixed models. RESULTS There were few differences between groups. In both treatment groups, improvements in BMI, ED symptomatology, distress levels, and clinical impairment were maintained or increased further. Estimated mean BMI change from baseline to 24 months was 2.16 kg/m(2) for SSCM and 2.25 kg/m(2) for MANTRA (effect sizes of 1.75 and 1.83, respectively). Most participants (83%) did not require any additional intensive treatments (e.g., hospitalization). Two SSCM patients became overweight through binge-eating. DISCUSSION Both treatments have value as outpatient interventions for patients with AN.

Two Year Follow-Up of the MOSAIC Trial

OBJECTIVE This study reports follow-up data from a multicenter randomized controlled trial (n = 142) comparing the Maudsley Model of Anorexia Nervosa Treatment for Adults (MANTRA) with Specialist Supportive Clinical Management (SSCM) in outpatients with broadly defined anorexia nervosa (AN). At 12 months postrandomization, all patients had statistically significant improvements in body mass index (BMI), eating disorder (ED) symptomatology and other outcomes with no differences between groups. MANTRA was more acceptable to patients. The present study assessed whether gains were maintained at 24 months postrandomization. METHODS Follow-up data at 24 months were obtained from 73.2% of participants. Outcome measures included BMI, ED symptomatology, distress, impairment, and additional service utilization during the study period. Outcomes were analyzed using linear mixed models. RESULTS There were few differences between groups. In both treatment groups, improvements in BMI, ED symptomatology, distress levels, and clinical impairment were maintained or increased further. Estimated mean BMI change from baseline to 24 months was 2.16 kg/m(2) for SSCM and 2.25 kg/m(2) for MANTRA (effect sizes of 1.75 and 1.83, respectively). Most participants (83%) did not require any additional intensive treatments (e.g., hospitalization). Two SSCM patients became overweight through binge-eating. DISCUSSION Both treatments have value as outpatient interventions for patients with AN.

Single-Session Transcranial Direct Current Stimulation Temporarily Improves Symptoms, Mood, and Self-Regulatory Control in Bulimia Nervosa: A Randomised Controlled Trial

Background Evidence suggests that pathological eating behaviours in bulimia nervosa (BN) are underpinned by alterations in reward processing and self-regulatory control, and by functional changes in neurocircuitry encompassing the dorsolateral prefrontal cortex (DLPFC). Manipulation of this region with transcranial direct current stimulation (tDCS) may therefore alleviate symptoms of the disorder. Objective This double-blind sham-controlled proof-of-principle trial investigated the effects of bilateral tDCS over the DLPFC in adults with BN. Methods Thirty-nine participants (two males) received three sessions of tDCS in a randomised and counterbalanced order: anode right/cathode left (AR/CL), anode left/cathode right (AL/CR), and sham. A battery of psychological/neurocognitive measures was completed before and after each session and the frequency of bulimic behaviours during the following 24-hours was recorded. Results AR/CL tDCS reduced eating disorder cognitions (indexed by the Mizes Eating Disorder Cognitions Questionnaire-Revised) when compared to AL/CR and sham tDCS. Both active conditions suppressed the self-reported urge to binge-eat and increased self-regulatory control during a temporal discounting task. Compared to sham stimulation, mood (assessed with the Profile of Mood States) improved after AR/CL but not AL/CR tDCS. Lastly, the three tDCS sessions had comparable effects on the wanting/liking of food and on bulimic behaviours during the 24 hours post-stimulation. Conclusions These data suggest that single-session tDCS transiently improves symptoms of BN. They also help to elucidate possible mechanisms of action and highlight the importance of selecting the optimal electrode montage. Multi-session trials are needed to determine whether tDCS has potential for development as a treatment for adult BN.

Increasing Cognitive Load Reduces Interference from Masked Appetitive and Aversive but Not Neutral Stimuli

Interactions between cognition and emotion are important for survival, often occurring in the absence of awareness. These interactions have been proposed to involve competition between cognition and emotion for attentional resources. Emotional stimuli have been reported to impair performance on cognitive tasks of low, but not high, load if stimuli are consciously perceived. This study explored whether this load-dependent interference effect occurred in response to subliminal emotional stimuli. Masked emotional (appetitive and aversive), but not neutral, stimuli interfered with performance accuracy but not response time on a cognitive task (n-back) at low (1-back), but not high (2-back) load. These results show that a load-dependent interference effect applies to masked emotional stimuli and that the effect generalises across stimulus categories with high motivational value. This supports models of selective attention that propose that cognition and emotion compete for attentional resources. More specifically, interference from masked emotional stimuli at low load suggests that attention is biased towards salient stimuli, while dissipation of interference under high load involves top-down regulation of attention. Our data also indicate that top-down goal-directed regulation of attention occurs in the absence of awareness and does not require metacognitive monitoring or evaluation of bias over behaviour, i.e., some degree of self-regulation occurs at a non-conscious level.

Temporal Discounting and the Tendency to Delay Gratification across the Eating Disorder Spectrum

Bulimia nervosa (BN) and binge eating disorder (BED) have been associated with poorer reward-related inhibitory control, reflected by a reduced tendency to delay gratification. The opposite has been reported in anorexia nervosa (AN), but differences have not been directly compared across eating disorders (EDs). This study investigated self-reported (Delaying Gratification Inventory) and task-based (temporal discounting) inhibitory control in 66 women with an ED and 28 healthy controls (HCs). Poorer task-based inhibitory control was observed in the BN compared with the AN group and poorer self-reported inhibitory control in the BN and in the BED groups compared with the AN and the HC groups, suggesting that reward-related inhibitory control varies across EDs. Symptom severity correlated with poorer self-reported (but not task-based) inhibitory control across the EDs. These data provide some support for transdiagnostic mechanisms and highlight the importance of addressing perceived loss of control in the treatment of EDs. Copyright

Proactive and reactive inhibitory control in eating disorders

Altered inhibitory control has been implicated in the development and maintenance of eating disorders (ED), however it is unclear how different types of inhibitory control are affected across the EDs. We explored whether individuals with bulimia nervosa (BN), binge eating disorder (BED) and anorexia nervosa (AN) differed from healthy individuals (HC) on two types of motor inhibitory control: proactive inhibition (related to the preparation/initiation of a response) and reactive inhibition (withholding a response in reaction to a signal). Ninety-four women (28 AN, 27 BN, 11 BED, 28 HC) completed two neuropsychological tasks (a cued reaction time task and a stop signal task), and questionnaires assessing clinical variables, mood, anxiety, and inhibitory control. Self-reported inhibitory control was poorer in women with BN compared to the HC and AN groups, but greater in women with AN compared to all other groups. However, no group differences in reactive inhibition were observed. Proactive inhibition was augmented in women with AN compared to HC, and this was related to self-reported intolerance of uncertainty. The findings suggest that proactive inhibition may be a relevant target for behavioural interventions for AN, and call for further research into the relationship between intolerance of uncertainty and proactive inhibition.