Nothing tastes as good as skinny feels: the neurobiology of anorexia nervosa

CB1/5-HT/GABA interactions and food intake regulation

Despite historically the serotonergic, GABAergic, and cannabinoid systems have been shown to play a crucial role in the central regulation of eating behavior, interest in the study of the interactions of these neurotransmission systems has only now been investigated. Current evidence suggests that serotonin may influence normal and pathological eating behavior in significantly more complex ways than was initially thought. This knowledge has opened the possibility of exploring the potential clinical utility of new therapeutic strategies more effective and safer than the current approaches to treat pathological eating behavior. Furthermore, the nature and complexity of the interactions between these neurotransmitter systems have provided a better understanding of the pathophysiological mechanisms not only of eating behavior and eating disorders but also of some of the comorbidities associated with modulation of cortical circuits, which are involved in high order cognitive processes. Accordingly, in the present chapter, the clinical and experimental findings of the interactions between serotonin, GABA, and cannabinoids are synthesized, emphasizing the pharmacological, neurophysiological, and neuroanatomical aspects that could potentially improve the current therapeutic approaches against pathological eating behavior.

An update on eating disorders

Eating disorders are heterogeneous disorders characterised by a maladaptive drive to lose weight and, for the most part, by extreme fear of weight gain and overvaluation of thin body image. Calorie restriction, overexercise and purging behaviours put some sufferers at high risk of physical morbidity and mortality. Mental preoccupations interfere with social, professional and general quality of life. Patients’ defensive secrecy and compulsivity can make it hard to diagnose and treat such disorders despite the suffering they involve. Integrated medical and psychiatric intervention can save life and safely improve nutrition. Behavioural support – with family and carer involvement when appropriate – can counter the dysregulation that leads to vicious cycles of restriction–binge–purge, helping patients develop new skills to regulate emotion without weight losing. In the future, exciting developments in neuroimaging, neurosurgery and pharmacology may lead to ways to make the brain more responsive to therapy. Insights into risk factors may also improve preventive strategies in a climate of highly sophisticated international electronic communication.

Exploring Neural Mechanisms Related to Cognitive Control, Reward, and Affect in Eating Disorders: A Narrative Review of FMRI Studies

Studies using functional magnetic resonance imaging (fMRI) have contributed to our understanding of possible neural abnormalities among individuals with eating disorders. Many of these studies have focused on three domains: 1) cognitive control, 2) reward processing, and 3) affective processing. This review attempts to summarize the recent fMRI findings across these domains among the most well-characterized eating disorders: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). Though the literature is a bit murky, a few major themes have emerged. Cognitive control systems are affected among individuals across eating disorder diagnoses, but effects seem least pronounced in AN. Specifically, individuals with all eating disorders appear to show decreased prefrontal activation during cognitive control, but there is less evidence in AN linking decreased prefrontal activation with behavior. There is some evidence that the reinforcing value of food is reduced in AN, but individuals with BN and BED show hyperactivation to rewarding food-related stimuli, suggesting the reinforcing value of food may be enhanced. However, more complex reward processing paradigms show that individuals with BN and BED exhibit hypoactivation to reward anticipation and provide mixed results with regards to reward receipt. There are fewer neuroimaging findings related to affective processing, yet behavioral findings suggest affective processing is important in understanding eating disorders. Though the extant literature is complicated, these studies represent a foundation from which to build and provide insight into potential neurobiological mechanisms that may contribute to the pathophysiology of eating disorders.

Study protocol of comprehensive risk evaluation for anorexia nervosa in twins (CREAT): a study of discordant monozygotic twins with anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a severe disorder, for which genetic evidence suggests psychiatric as well as metabolic origins. AN has high somatic and psychiatric comorbidities, broad impact on quality of life, and elevated mortality. Risk factor studies of AN have focused on differences between acutely ill and recovered individuals. Such comparisons often yield ambiguous conclusions, as alterations could reflect different effects depending on the comparison. Whereas differences found in acutely ill patients could reflect state effects that are due to acute starvation or acute disease-specific factors, they could also reflect underlying traits. Observations in recovered individuals could reflect either an underlying trait or a "scar" due to lasting effects of sustained undernutrition and illness. The co-twin control design (i.e., monozygotic [MZ] twins who are discordant for AN and MZ concordant control twin pairs) affords at least partial disambiguation of these effects.

METHODS

Comprehensive Risk Evaluation for Anorexia nervosa in Twins (CREAT) will be the largest and most comprehensive investigation of twins who are discordant for AN to date. CREAT utilizes a co-twin control design that includes endocrinological, neurocognitive, neuroimaging, genomic, and multi-omic approaches coupled with an experimental component that explores the impact of an overnight fast on most measured parameters.

DISCUSSION

The multimodal longitudinal twin assessment of the CREAT study will help to disambiguate state, trait, and "scar" effects, and thereby enable a deeper understanding of the contribution of genetics, epigenetics, cognitive functions, brain structure and function, metabolism, endocrinology, microbiology, and immunology to the etiology and maintenance of AN.

The Anticipation and Perception of Affective Touch in Women with and Recovered from Anorexia Nervosa

Disruptions in reward processing and anhedonia have long been observed in Anorexia Nervosa (AN). Interoceptive deficits have also been observed in AN, including reduced tactile pleasure. However, the extent to which this tactile anhedonia is specifically liked to an impairment in a specialised, interoceptive C-tactile system originating at the periphery, or a more top-down mechanism in the processing of tactile pleasantness remains debated. Here, we investigated differences between patients with and recovered from AN (RAN) and healthy controls (HC) in the perception of pleasantness of touch delivered in a CT-optimal versus a CT-non-optimal manner, and in their top-down, anticipatory beliefs about the perceived pleasantness of touch. To this end, we measured the anticipated pleasantness of various materials touching the skin and the perceived pleasantness of light, dynamic touch applied to the forearm of 27 women with AN, 24 women who have recovered and 30 HCs using C Tactile (CT) afferents-optimal (slow) and non-optimal (fast) velocities. Our results showed that both clinical groups anticipated tactile experiences and rated delivered tactile stimuli as less pleasant than HCs, but the latter difference was not related to the CT optimality of the stimulation. Instead, differences in the perception of CT-optimal touch were predicted by differences in top-down beliefs, alexithymia and interoceptive sensibility. Thus, tactile anhedonia in AN might persist as a trait even after otherwise successful recovery of AN and it is not linked to a bottom-up interoceptive deficit in the CT system, but rather to a learned, defective top-down anticipation of tactile pleasantness.

Developmental stage-dependent relationships between ghrelin levels and hippocampal white matter connections in low-weight anorexia nervosa and atypical anorexia nervosa

INTRODUCTION

Disruptions in homeostatic and hedonic food motivation are proposed to underlie anorexia nervosa (AN) and atypical AN, restrictive eating disorders which commonly onset in puberty. Ghrelin, a neuroprotective hormone that drives hedonic eating is increased in AN and is expressed in the hippocampus. White matter (WM) undergoes significant change during puberty in regions involved in food motivation, particularly WM tracts connected with the hippocampus. The association between ghrelin and WM region of interest (ROI) with hippocampal connections in restrictive eating disorders, particularly in adolescence during key neurodevelopmental growth, is unknown.

METHODS

We evaluated fasting plasma ghrelin and WM microstructure (measured by free-water corrected fractional anisotropy (FA-t)) in WM ROIs with hippocampal connections - the fornix and the hippocampal portion of the cingulum - in 56 adolescent females (age range: 11.9 - 22.1 y; mean: 19.0 y) with low-weight eating disorders including AN and atypical AN (N = 36) and healthy controls (N = 20).

RESULTS

FA-t in the fornix or hippocampal portion of the fornix did not differ between groups. Ghrelin was higher in AN/atypical AN vs. HC and was positively correlated with puberty stage in the AN/atypical AN group, but not the HC group. The correlation between ghrelin and FA-t in the fornix was significantly different in females with AN/atypical AN compared to controls. In AN/atypical AN, pubertal stage moderated the relation between fasting plasma ghrelin and FA-t in the fornix: higher fasting ghrelin was associated with lower FA-t in the fornix in late-post-puberty, but was not associated with FA-t in the early to mid stages of puberty.

CONCLUSIONS

In post-pubertal females with low-weight AN/atypical AN, higher levels of ghrelin are associated with lower FA-t in the fornix. This relationship is not evident in the early to mid stages of puberty in AN/atypical AN or in HC, and may reflect a lack of possible neuroprotective effects of ghrelin in late-post puberty only. Understanding the effects of ghrelin on WM microstructure longitudinally and following recovery from AN/Atypical AN and how this differs across pubertal stages will be an important next step. These findings could ultimately inform treatment staging and aid in diagnosis and detection of AN/atypical AN.

Short-term metreleptin treatment of patients with anorexia nervosa: rapid on-set of beneficial cognitive, emotional, and behavioral effects

To examine the hypothesis that normalization of low circulating leptin levels in patients with anorexia nervosa ameliorates hyperactivity, three seriously ill females with hyperactivity were treated off-label with metreleptin (recombinant human leptin) for up to 14 days. Drive for activity, repetitive thoughts of food, inner restlessness, and weight phobia decreased in two patients. Surprisingly, depression improved rapidly in all patients. No serious adverse events occurred. Due to obvious limitations of uncontrolled case series, placebo-controlled clinical trials are mandatory to confirm the observed rapid onset of beneficial effects. Our findings suggest an important role of hypoleptinemia in the mental and behavioral phenotype of anorexia nervosa.

Decreased cerebral opioid receptors availability related to hormonal and psychometric profile in restrictive-type anorexia nervosa

PURPOSE

The opioid system role in anorexia nervosa (AN) pathophysiology is still unclear since conflicting results were reported on peripheral and cerebrospinal fluid opioids levels. The study main aim was to evaluate cerebral AN opiate receptor availability by using [¹¹C] diprenorphine, a ligand with non-selective binding.

METHODS

In vivo [¹¹C]diprenorphine cerebral non-displaceable binding potential (BP_ND) evaluated by PET imaging was compared between three groups : 17 undernourished restrictive-type AN patients (LeanAN), 15 AN patients having regained normal weight (RecAN) and 15 controls. A lower BP_ND may account for an increased opioid tone and vice versa. Serum hormones and endogenous opioids levels, eating-related and unspecific psychological traits were also evaluated.

RESULTS

Compared to controls, LeanAN and RecAN patients had decreased [¹¹C]diprenorphine BP_ND in middle frontal gyrus, temporo-parietal cortices, anterior cingulate cortex and in left accumbens nucleus. Hypothalamo-pituitary (H-P), left amygdala and insula BP_ND was found decreased only in LeanAN and that of putamen only in RecAN. LeanAN presented higher dynorphin A and enkephalin serum levels than in controls or RecAN. Inverse correlations were found in total group between : 24 h mean serum cortisol levels and anterior cingulate gyrus or insula BP_ND; eating concern score and left amygdala BP_ND. Positive correlation were found between leptin and hypothamus BP_ND; LH and pituitary BP_ND.

CONCLUSIONS

Low opiate receptor availability may be interpreted as an increased opioid tone in areas associated with both reward/aversive system in both AN groups. The relationship between the opioid receptors activity and hypercorticism or specific psychometric scores in some of these regions suggests adaptive mechanisms facing anxiety but also may play a role in the disease perpetuation.

A tasting experiment comparing food and nutritional supplement in anorexia nervosa

Anorexia nervosa (AN) is a severe psychiatric disorder leading to life-threatening emaciation. Weight restoration is crucial in treatment but few data are available on how to achieve it. Nutritional supplements are needed in treatment but patients' preferences about natural versus medical foods and their gustatory/hedonic perception are unclear. We aimed to measure disgust and reward-based eating in AN and to assess psychological, interoceptive awareness-related, behavioral, and hedonic aspects comparing natural versus medical food. Thirty-three inpatients with AN and 39 healthy controls (HCs) were recruited and received 50 ml of either apricot juice or nutritional liquid supplement with apricot flavor on two consecutive days. Disgust, reward-based eating, and eating psychopathology were evaluated. Visual Analogue Scales measuring anxiety, hunger, confusion about internal states, need for over-exercise, restraint, and satiety were completed before and after the experiment. Disgust and hedonic responses were measured after the experiment. Patients with AN reported preserved disgust sensitivity and higher reward-based eating drive. When compared to HCs, inpatients with AN reported higher scores on anxiety, hunger, confusion about internal states, urge to over-exercise, urge to eating restraint, and satiety before and after the tasting experiment. The supplement slightly increased patients' anxiety with HCs reporting the same trend. Still, patients reported more food-related disgust after the supplement but their overall hedonic evaluation was similar for both conditions. Also, anxiety, confusion about internal states, and urge to over-exercise and restraint did not significantly increase after consuming either food. Therefore, if we take into account patients' level of heightened satiety and suppressed hunger, supplements could be helpful for patients with severe AN since greater energy intakes could be provided with only small volumes of food and little changes of eating concerns.

Anorexia nervosa, zinc deficiency and the glutamate system: The ketamine option

Anorexia nervosa (AN) is a severe, biological brain disorder with significant medical risks and a tenacious development over time. Unfortunately, few treatments show efficacy in people with AN although numerous therapies including pharmacological have been explored. Zinc deficiency has been implicated in AN and zinc is important in a large range of processes in the brain. In particular, it is an allosteric modulator of NMDA receptors - the maintenance of zinc levels within a normal, narrow range is essential for glutamatergic functioning. Chronic zinc deficiency increases neuronal stores of calcium and reduces direct modulation of NMDA receptors which collectively lead to overactivation and upregulation of NMDA receptors. This may facilitate pathologically high levels of glutamate, calcium influx and subsequent excitotoxicity, which can disrupt synaptogenesis and synaptic plasticity. While studies of zinc supplementation in AN have shown some promise, the efficacy of this treatment is limited. This may be due to AN illness chronicity and the significant changes already made, as well as a reduced potency of zinc to inhibit NMDA receptors in a pathological state. Thus, we propose that the safe (at low doses) yet more potent NMDA receptor antagonist, ketamine, may act to normalise a perturbed glutamatergic system and increase synaptogenesis in the short term. This 'kickstart' via ketamine could then allow zinc supplementation and other forms of treatment to enhance recovery in AN.

Striatal volumes as potential biomarkers in Eating Disorders: A pilot study

INTRODUCTION

Differences in bulimic and impulsive behaviours in Eating Disorders (ED) have been associated with cortico-striatal circuit dysfunction at a neurobiological level. We sought to investigate neo-striatal volume as a biomarker in ED subgroups as well as the possible relationship with trauma history.

MATERIAL AND METHODS

We studied 24 female patients: Anorexia Nervosa AN (n=8), Bulimia Nervosa BN (n=9), comorbid ED with borderline personality disorder (EDc; n=7), and a group of Healthy Controls (n=19). Binge eating behaviours and impulsivity scales were used to characterize our sample as well as Trauma Questionnaires and Magnetic resonance imaging (MRI) volumetric manual measurements of caudate and putamen nuclei (striatum).

RESULTS

Our preliminary results showed a significantly larger left putaminal volume in AN compared to the other three groups [C (p=0.008), BN (p<.001) and EDc (p=.001)] and a smaller right putaminal volume in EDc compared to controls (p=.045) and AN (p=.039). Some negative correlations were found between bilateral putaminal volumes and self-reported general and early traumatization scores.

CONCLUSION

This pilot study suggested that striatal volumes might differentiate AN from BN and EDc at a neurobiological level with implications for treatment strategies. Larger scale studies should be carried out that allow replication of these data.

Moving towards specificity: A systematic review of cue features associated with reward and punishment in anorexia nervosa

Models of anorexia nervosa (AN) posit that symptoms are maintained through deficient reward and enhanced punishment processing. However, theoretical and empirical inconsistencies highlight the need for a more nuanced conceptualization of this literature. Our goal was to comprehensively review the research on reward and punishment responding in AN from a cue-specific lens to determine which stimuli evoke or discourage reward and punishment responses in this population, and, ultimately, what properties these rewarding and punishing cues might share. A systematic review interrogating reward and punishment responses to specific cues yielded articles (n = 92) that examined responses to disorder relevant (e.g., food) and irrelevant (e.g., money) stimuli across self-report, behavioral, and biological indices. Overall, in most studies individuals with AN exhibited aversive responses to cues signaling higher body weights, social contexts, and monetary losses, and appetitive responses to cues for weight loss behaviors and thinness. Findings were more mixed on responses to palatable food and monetary gains. Results highlight that reward and punishment responding in AN are context specific and may be affected by varied stimulus qualities (e.g., predictability, controllability, delay, effort). Increasing specificity in future research on reward and punishment mechanisms in AN will better inform development of precisely-targeted interventions.

Overcontrol and neural response to errors in pediatric anxiety disorders

Multiple risk factors that may contribute to the development and severity of pediatric anxiety disorders, one of which is dimensional overcontrol. Overcontrol is a constellation of characteristics including heightened performance monitoring, inflexibility, perfectionism and aversion to making mistakes. In this study, we examined overcontrol in children with anxiety disorders and tested whether the underlying dimension of overcontrol specifically explains altered brain response to errors in pediatric anxiety disorders. Parent-reported scores of child overcontrol were collected in a sample of children (ages 8-12 years) with (n = 35) and without (n = 34) anxiety disorders and the relationship of overcontrol and anxiety symptoms to neural responding to errors during functional magnetic resonance imaging (fMRI) was examined. Results indicated childhood overcontrol was elevated in pediatric anxiety disorders and was significantly associated with anxiety severity, even when controlling for comorbid depression and ADHD. Additionally, overcontrol was associated with reduced neural response to errors versus correct responses in the bilateral dorsal anterior cingulate cortex (dACC) and insula, even when controlling for anxiety symptoms. Overcontrol may serve as an underlying mechanism associated with clinical pediatric anxiety that demonstrates significant associations with aberrant neural error responding. Overcontrol may be an underlying mechanism contributing to pediatric anxiety that could be targeted for early intervention.

A further assessment of decision-making in anorexia nervosa

Objective:

Anorexia nervosa (AN) may be associated with impaired decision-making. Cognitive processes underlying this impairment remain unclear, mainly because previous assessments of this complex cognitive function were completed with a single test. Furthermore, clinical features such as mood status may impact this association. We aim to further explore the hypothesis of altered decision-making in AN.

Method:

Sixty-three adult women with AN and 49 female controls completed a clinical assessment and were assessed by three tasks related to decision-making [Iowa Gambling Task (IGT), Balloon Analogue Risk Task (BART), Probabilistic Reversal Learning Task (PRLT)].

Results:

People with AN had poorer performance on the IGT and made less risky choices on the BART, whereas performances were not different on PRLT. Notably, AN patients with a current major depressive disorder showed similar performance to those with no current major depressive disorder.

Conclusion:

These results tend to confirm an impaired decision making-process in people with AN and suggest that various cognitive processes such as inhibition to risk-taking or intolerance of uncertainty may underlie this condition Furthermore, these impairments seem unrelated to the potential co-occurent major depressive disorders.

The relationship of autistic traits to taste and olfactory processing in anorexia nervosa

BACKGROUND

There is a heightened prevalence of autism in anorexia nervosa (AN) compared to the general population. Autistic people with AN experience a longer illness duration and poorer treatment outcomes. Whether sensory differences in autism could contribute to altered taste and smell as a potential maintaining factor in AN is under-explored. The aim of this study was to explore whether autistic traits are associated with taste and olfaction differences in AN.

METHODS

The study recruited n = 40 people with AN, and n = 40 healthy controls (HC). Smell sensitivity was measured using the Sniffin' Sticks test. Taste sensitivity was measured using taste strips. Participants self-rated their autistic traits using the Autism Spectrum Quotient.

RESULTS

There were no significant differences on taste and olfactory outcomes between people with AN and HC. These findings did not change after controlling for the heightened levels of autistic traits in the AN group. No relationship between taste and smell outcomes and autistic traits were identified within the AN group.

LIMITATIONS

The current study is not able to draw conclusions about taste and smell processing in co-occurring autism and AN as it only measured levels of autistic traits, rather than comparing people with and without an autism diagnosis.

CONCLUSIONS

No significant associations between autistic traits and taste and smell processing in AN were identified. Future research should consider further exploring this area, including by comparing autistic women to women with AN.

Dopaminergic activity and exercise behavior in anorexia nervosa

Driven exercise (i.e., the tendency to exercise in excess to influence weight/shape or regulate emotion) is difficult to manage in the context of anorexia nervosa, and is associated with poorer treatment outcomes, and psychological and medical severity. Driven exercise is observed in a considerable number of those diagnosed with anorexia nervosa; however, to date, this hallmark symptom remains poorly understood. Dopamine signaling is implicated in motivating and maintaining appetitive behavior among patients with eating disorders; but, much less is known about the role of dopamine signaling specific to the symptom of driven exercise. An improved understanding of this biobehavioral mechanism may inform the etiology of driven exercise in anorexia nervosa, with the potential to impact future research and treatment efforts. This review describes the role that dopamine serves in maintaining symptoms in the context of anorexia nervosa, and synthesizes current relevant evidence on exercise in AN and related dopaminergic activity. Throughout, theoretical implications are discussed, along with critical directions for future research.

Lower gray matter volumes of frontal lobes and insula in adolescents with anorexia nervosa restricting type: Findings from a Brain Morphometry Study

BACKGROUND

Brain atrophy in anorexia nervosa (AN) is one of the most marked structural brain changes observed in mental disorders. In this study, we propose a whole brain analysis approach to characterize global and regional cerebral volumes in adolescents with restricting-type anorexia nervosa (AN-r).

METHODS

A total of 48 adolescent females (age range 13-18 years) were enrolled in the study (24 right-handed AN-r in the early stages of the illness and treated in the same clinical setting and 24 age-matched healthy controls [HC]). High-resolution T1-weighted magnetic resonance images were acquired. Cerebral volumes, including the total amounts of gray matter (GM), white matter (WM), and cerebrospinal fluid (CSF) were obtained with the Statistical Parametric Mapping software (SPM8); specific cortical regional volumes were computed by applying an atlas-based cortical parcellation to the SPM8 GM segments. Analysis of variance (ANOVA) was performed to identify any significant between-group differences in global and regional brain volumes.

RESULTS

The analyses revealed reduced total GM volumes (p = 0.02) and increased CSF (p = 0.05) in AN-r, compared with HC. No significant between-group difference was found in WM volumes. At the regional level, significantly lower GM volumes in both frontal lobes (p = 0.006) and in the left insula (p = 0.016) were detected. No significant relationships were found between cerebral volumes and duration of illness, psychiatric comorbidities, psychopharmacological treatment, prepubertal phase, or presence of amenorrhea.

CONCLUSIONS

The topographic distribution of GM reduction in a homogenous group of AN-r involves regions responsible for the emotional and cognitive deficits associated with the illness. These findings are discussed in relation to the roles of the insular cortex and the frontal lobes.

White Matter Abnormalities in Anorexia Nervosa: Psychoradiologic Evidence From Meta-Analysis of Diffusion Tensor Imaging Studies Using Tract Based Spatial Statistics

Background: Anorexia nervosa (AN) is a debilitating illness whose neural basis remains unclear. Studies using tract-based spatial statistics (TBSS) with diffusion tensor imaging (DTI) have demonstrated differences in white matter (WM) microarchitecture in AN, but the findings are inconclusive and controversial.

Objectives: To identify the most consistent WM abnormalities among previous TBSS studies of differences in WM microarchitecture in AN.

Methods: By systematically searching online databases, a total of 11 datasets were identified, including 245 patients with AN and 246 healthy controls (HC). We used Seed-based d Mapping to analyze fractional anisotropy (FA) differences between AN patients and HC, and performed meta-regression analysis to explore the effects of clinical characteristics on WM abnormalities in AN.

Results: The pooled results of all AN patients showed robustly lower FA in the corpus callosum (CC) and the cingulum compared to HC. These two regions preserved significance in the sensitivity analysis as well as in all subgroup analyses. Fiber tracking showed that the WM tracts primarily involved were the body of the CC and the cingulum bundle. Meta-regression analysis revealed that the body mass index and mean age were not linearly correlated with the lower FA.

Conclusions: The most consistent WM microstructural differences in AN were in the interhemispheric connections and limbic association fibers. These common “targets” advance our understanding of the complex neural mechanisms underlying the puzzling symptoms of AN, and may help in developing early treatment approaches.

Salivary opiorphin levels in anorexia nervosa: A case-control study

Objectives: Opiorphin is a physiological inhibitor of peptidases inactivating endogenous opioids displaying strong analgesic properties without undesirable side effects, antidepressant properties or hormonal dependency. It might therefore play an important role in patients with painful diseases related to neuro-hormonal dysregulation of the nervous system, affecting saliva secretion and composition such as anorexia nervosa (AN). The main objective aim of this study was to compare the level of opiorphin in saliva of patients with AN to matched subjects free of eating disorders.Methods: A case-control clinical trial was conducted in 68 AN patients and 43 healthy matched control subjects. Depression symptoms were assessed with the self-scored questionnaire Beck Depression Inventory (BDI) and salivary samples were taken during the acute stage of AN (BMI <15 kg/m²) for measuring opiorphin. Opiorphin levels were measured with a quantitative assay using a commercial immunoenzymatic Elisa kit (cat no. EH1927, Wuchan, Hubei, China).Results: No statistically significant difference was found in salivary opiorphin levels between the AN and control groups, (P = 0.499, Mann-Whitney U-test). Positive correlations to duration of the disease, BDI and bodyweight in AN patients were evidenced.Conclusions: Measurement of salivary opiorphin levels cannot be used as a marker of AN but may allow new perspectives in monitoring AN in its early stages.

Intact value-based decision-making during intertemporal choice in women with remitted anorexia nervosa? An fMRI study

BACKGROUND

Extreme restrictive food choice in anorexia nervosa is thought to reflect excessive self-control and/or abnormal reward sensitivity. Studies using intertemporal choice paradigms have suggested an increased capacity to delay reward in anorexia nervosa, and this may explain an unusual ability to resist immediate temptation and override hunger in the long-term pursuit of thinness. It remains unclear, however, whether altered delay discounting in anorexia nervosa constitutes a state effect of acute illness or a trait marker observable after recovery.

METHODS

We repeated the analysis from our previous fMRI investigation of intertemporal choice in acutely underweight patients with anorexia nervosa in a sample of weight-recovered women with anorexia nervosa (n = 36) and age-matched healthy controls (n = 36) who participated in the same study protocol. Follow-up analyses explored functional connectivity separately in both the weight-recovered/healthy controls sample and the acute/healthy controls sample.

RESULTS

In contrast to our previous findings in acutely underweight patients with anorexia nervosa, we found no differences between weight-recovered patients with anorexia nervosa and healthy controls at either behavioural or neural levels. New analysis of data from the acute/healthy controls sample sample revealed increased coupling between dorsal anterior cingulate cortex and posterior brain regions as a function of decision difficulty, supporting the hypothesis of altered neural efficiency in the underweight state.

LIMITATIONS

This was a cross-sectional study, and the results may be task-specific.

CONCLUSION

Although our results underlined previous demonstrations of divergent temporal reward discounting in acutely underweight patients with anorexia nervosa, we found no evidence of alteration in patients with weight-recovered anorexia nervosa. Together, these findings suggest that impaired valuebased decision-making may not constitute a defining trait variable or “scar” of the disorder.

Neural Mechanisms in Eating Behaviors: A Pilot fMRI Study of Emotional Processing

OBJECTIVE

Emotional processing dysfunction evident in eating disorders (ED) such as anorexia nervosa (AN) and bulimia nervosa (BN), is considered relevant to the development and maintenance of these disorders. The purpose of the current functional magnetic resonance imaging (fMRI) study was to pilot a comparison of the activity of the fronto-limbic and fronto-striatal brain areas during an emotion processing task in persons with ED.

METHODS

24 women patients with ED were scanned, while showing emotionally stimulating (pleasant, unpleasant) and neutral images from the International Affective Picture System (IAPS).

RESULTS

During the pleasant condition, significant differences in Dorsolateral Prefrontal Cortex (DLPFC) activations were found with AN participants presenting greater activation compared to BN and ED comorbid groups (EDc) and healthy controls also showing greater activation of this brain area compared to BN and EDc. Left putamen was less activated in EDc compared to both controls (C) and AN. During the unpleasant condition, AN participants showed hyperactivation of the Orbito-frontal Cortex (OFC) when compared to EDc.

CONCLUSION

This study highlights the potential functional relevance of brain areas that have been associated with self-control. These findings should help advance understanding the neural substrate of ED, though they should be considered as preliminary and be cautiously interpreted.

Rethinking Therapeutic Strategies for Anorexia Nervosa: Insights From Psychedelic Medicine and Animal Models

Anorexia nervosa (AN) has the highest mortality rate of any psychiatric disease, yet available pharmacological treatments are largely ineffective due, in part, to an inadequate understanding of the neurobiological drivers that underpin the condition. The recent resurgence of research into the clinical applications of psychedelic medicine for a range of mental disorders has highlighted the potential for classical psychedelics, including psilocybin, to alleviate symptoms of AN that relate to serotonergic signaling and cognitive inflexibility. Clinical trials using psychedelics in treatment-resistant depression have shown promising outcomes, although these studies are unable to circumvent some methodological biases. The first clinical trial to use psilocybin in patients with AN commenced in 2019, necessitating a better understanding of the neurobiological mechanisms through which psychedelics act. Animal models are beneficial in this respect, allowing for detailed scrutiny of brain function and behavior and the potential to study pharmacology without the confounds of expectancy and bias that are impossible to control for in patient populations. We argue that studies investigating the neurobiological effects of psychedelics in animal models, including the activity-based anorexia (ABA) rodent model, are particularly important to inform clinical applications, including the subpopulations of patients that may benefit most from psychedelic medicine.

Body shape in inpatients with severe anorexia nervosa

BACKGROUND

Anorexia nervosa (AN) is a severe mental disorder. Body shape disturbances are key in the development and maintenance of AN. Only few data are available on inpatients with life-threatening AN. Therefore, we aimed to investigate if body shape difficulties-with a focus on both body checking and avoidance-could improve during hospitalization in both subtypes of AN and to ascertain eventual associations between body shape concerns upon admission and clinical outcome.

METHODS

Upon hospital admission and end of treatment (EOT), 139 inpatients with AN completed Body Shape Questionnaire (BSQ), Body Checking Questionnaire (BCQ), and Body Image Avoidance Questionnaire (BIAQ) in addition to measures of eating and general psychopathology.

RESULTS

Patients with severe AN reported improved BSQ and BIAQ scores at EOT while BCQ did not significantly change. Diagnostic subtypes differed only in baseline BSQ scores and had an impact on the improvement in BSQ at EOT. Baseline BCQ was associated with patients' clinical improvement at EOT, even after controlling for age, duration of illness, Body Mass Index, depression, and anxiety scores.

CONCLUSIONS

Data on body shape concerns and their trajectory during hospitalization for severe AN are lacking; our findings provide support to the effectiveness of hospitalization in improving body shape concerns and body avoidance, but not body checking. Also, baseline body shape concerns (especially body checking) impacted on clinical improvement. Future research is needed to identify treatments that could further improve the therapeutic approach to severe patients of AN in the acute setting.

Neuroscience of Adolescent Anorexia Nervosa: Implications for Family-Based Treatment (FBT)

Over the past 20 years significant progress has been made to elucidate some of the neurobiological underpinnings of the development and maintenance of anorexia nervosa and their possible implications for treatment. There is increasing evidence supporting the notion that anorexia nervosa shares neurobehavioral patterns with anxiety disorders and involves reward processing aberrations and habit formation. There is consensus for the need of early intervention to ameliorate the effects of starvation on the adolescent brain and the effects of illness duration on neurodevelopment. Family-based treatment (FBT) is the first line evidence-based treatment for adolescents with anorexia nervosa achieving sustainable full remission rates of over 40%. FBT has an agnostic treatment approach and its mechanisms of change have until now not been fully understood. To help fill this gap in theoretical understanding, this paper will provide a review of the treatment model of FBT through a neuroscientific lens. It argues that FBT is well designed to address the implications of current key findings of the neuroscience of anorexia nervosa and that it is also well aligned with the current understanding of neuroscience principles underpinning therapeutic change. The paper supports the perspective that FBT utilizes principles of parent facilitated exposure response prevention. It concludes that an integration of a neuroscience perspective to the provision of FBT will assist the clinician in their practice of FBT.

Altered global brain network topology as a trait marker in patients with anorexia nervosa

BACKGROUND

Resting state functional magnetic resonance imaging studies have identified functional connectivity patterns associated with acute undernutrition in anorexia nervosa (AN), but few have investigated recovered patients. Thus, a trait connectivity profile characteristic of the disorder remains elusive. Using state-of-the-art graph-theoretic methods in acute AN, the authors previously found abnormal global brain network architecture, possibly driven by local network alterations. To disentangle trait from starvation effects, the present study examines network organization in recovered patients.

METHODS

Graph-theoretic metrics were used to assess resting-state network properties in a large sample of female patients recovered from AN (recAN, n = 55) compared with pairwise age-matched healthy controls (HC, n = 55).

RESULTS

Indicative of an altered global network structure, recAN showed increased assortativity and reduced global clustering as well as small-worldness compared with HC, while no group differences at an intermediate or local network level were evident. However, using support-vector classifier on local metrics, recAN and HC could be separated with an accuracy of 70.4%.

CONCLUSIONS

This pattern of results suggests that long-term recovered patients have an aberrant global brain network configuration, similar to acutely underweight patients. While the finding of increased assortativity may represent a trait marker of AN, the remaining findings could be seen as a scar following prolonged undernutrition.

Hypothalamic Structural and Functional Imbalances in Anorexia Nervosa

The hypothalamus contains integrative systems that support life, including physiological processes such as food intake, energy expenditure, and reproduction. Here, we show that anorexia nervosa (AN) patients, contrary to normal weight and constitutionally lean individuals, respond with a paradoxical reduction in hypothalamic levels of glutamate/glutamine (Glx) upon feeding. This reversal of the Glx response is associated with decreased wiring in the arcuate nucleus and increased connectivity in the lateral hypothalamic area, which are involved in the regulation on a variety of physiological and behavioral functions including the control of food intake and energy balance. The identification of distinct hypothalamic neurochemical dysfunctions and associated structural variations in AN paves the way for the development of new diagnostic and treatment strategies in conditions associated with abnormal body mass index and a maladaptive response to negative energy balance.

Abnormal Spontaneous Regional Brain Activity in Young Patients With Anorexia Nervosa

OBJECTIVE

Functional magnetic resonance imaging (fMRI) studies have repeatedly shown alterations in patients with anorexia nervosa (AN). These alterations might be driven by baseline signal characteristics such as the (fractional) amplitude of low frequency fluctuations (fALFF/ALFF), as well as regional signal consistency (ie, regional homogeneity [ReHo]) within circumscribed brain regions. Previous studies have also demonstrated gray matter (pseudo-) atrophy in underweight individuals with AN. Here we study fALFF/ALFF and ReHo in predominantly adolescent patients with AN, while taking gray matter changes into consideration.

METHOD

Resting state fMRI data were acquired from a sample of 148 female volunteers: 74 underweight patients with AN and 74 age-matched female healthy controls (HC).

RESULTS

Group differences for fALFF and ReHo measures were found in several AN-relevant brain regions, including networks related to cognitive control, habit formation, and the ventral visual stream. Furthermore, the magnitude of correlation between gray matter volume/thickness and fALFF and ReHo were reduced in AN compared to HC.

CONCLUSION

Abnormal local resting state characteristics in AN-related brain-networks as well as reduced structure-function relationships may help to explain previously reported task-related and classical resting state neural alterations in underweight AN. Patients with AN may serve as a valuable population for investigating dynamic changes in the relationships between brain structure and function.

Anorexia nervosa and diffusion weighted imaging: An open methodological question raised by a systematic review and a fractional anisotropy anatomical likelihood estimation meta-analysis

BACKGROUND

Anorexia nervosa (AN) is characterized by white matter abnormalities in neuroimaging studies. Fractional anisotropy (FA) is a diffusion tensor imaging (DTI) index that is considered an instrument for the evaluation of white matter alterations. However, the literature has recently pointed out the role of the partial volume effect (PVE) as a confounding factor for the identification of juxtaposed tissues. Our goal was to review the DTI literature in AN and evaluate possible confounding factors linked to the reported results.

METHOD

A systematic review of the literature was conducted to identify Diffusion Tensor Imaging studies of individuals with AN and, subsequently, an anatomical likelihood estimation (ALE) meta-analysis was performed on studies published before March 18, 2019.

RESULTS

Twenty-four studies (AN = 517, controls = 542) were included in the qualitative systematic review of the literature. Ten published studies underwent the ALE-analysis (AN = 210, controls = 229), plus data from an unpublished cohort (AN = 38, controls = 38). Two clusters of decreased FA were identified, namely in the left corona radiata, and in the left thalamus. Only one article took the PVE correction analysis into account.

CONCLUSIONS

The alterations identified must be considered within the limits of a possible methodological bias regarding PVE and free water and re-analysis of the data may be recommended. The preliminary data showed that the alteration of white matter pathways between the limbic structures and brain cortex may be linked to the processing of somatosensory information that could play a key role in the psychopathology of the disorder.

Age- and Sex-Specific Plasticity in Dopamine Transporter Function Revealed by Food Restriction and Exercise in a Rat Activity-Based Anorexia Paradigm

Eating disorders such as anorexia typically emerge during adolescence, are characterized by engagement in compulsive and detrimental behaviors, and are often comorbid with neuropsychiatric disorders and drug abuse. No effective treatments exist. Moreover, anorexia lacks adolescent animal models, contributing to a poor understanding of underlying age-specific neurophysiological disruptions. To evaluate the contribution of dopaminergic signaling to the emergence of anorexia-related behaviors during the vulnerable adolescent period, we applied an established adult activity-based anorexia (ABA) paradigm (food restriction plus unlimited exercise access for 4 to 5 days) to adult and adolescent rats of both sexes. At the end of the paradigm, measures of plasma volume, blood hormone levels, dopamine transporter (DAT) expression and function, acute cocaine-induced locomotion, and brain water weight were taken. Adolescents were dramatically more affected by the ABA paradigm than adults in all measures. In vivo chronoamperometry and cocaine locomotor responses revealed sex-specific changes in adolescent DAT function after ABA that were independent of DAT expression differences. Hematocrit, insulin, ghrelin, and corticosterone levels did not resemble shifts typically observed in patients with anorexia, though decreases in leptin levels aligned with human reports. These findings are the first to suggest that food restriction in conjunction with excessive exercise sex-dependently and age-specifically modulate DAT functional plasticity during adolescence. The adolescent vulnerability to this relatively short manipulation, combined with blood measures, evidence need for an optimized age-appropriate ABA paradigm with greater face and predictive validity for the study of the pathophysiology and treatment of anorexia. SIGNIFICANCE STATEMENT: Adolescent rats exhibit a distinctive, sex-specific plasticity in dopamine transporter function and cocaine response after food restriction and exercise access; this plasticity is both absent in adults and not attributable to changes in dopamine transporter expression levels. These novel findings may help explain sex differences in vulnerability to eating disorders and drug abuse during adolescence.

Functional Connectivity Patterns and the Role of 5-HTTLPR Polymorphism on Network Architecture in Female Patients With Anorexia Nervosa

Introduction

Recent neuroimaging studies suggest that anorexia nervosa (AN) symptoms emerge from failures in the relationships between spatially distributed networks that support different cognitive, emotional, and somatosensory functions. The 5-HTTLPR genotype has been shown to modulate all these abilities in AN, as well as the connectivity patterns between brain regions that support their functioning. This study aims at exploring the presence of any difference in functional connectome properties between AN patients and healthy controls (HC) by means of graph theory tools. The effect of 5-HTTLPR genotype on regional and global network characteristics in AN and HC was also explored.

Methods

A sample of 74 subjects (38 HC, 36 AN) underwent a resting state functional magnetic resonance imaging and was genotyped for 5-HTTLPR polymorphism. Comparisons of network properties were made between the AN and HC groups and, within each group, between 5-HTTLPR carriers of low-functioning alleles and carriers of the long–long genotype.

Results

Patients with AN displayed lower network clustering than HC (p = 0.04 at Mann–Whitney U test). Based on both degree and betweenness, a different distribution of network hubs emerged in the two groups. In particular, the anterior part of the anterior cingulate cortex was a hub only in the patient group. A correlation emerged between differences in brain volumes between patients and HC and differences in degree values of basal ganglia, nodes in the insula, and those in the parietal cortex. Carriers of the short allele of the 5-HTTLPR polymorphism were characterized by lower small-world properties (p = 0.027) and modularity (p = 0.031) in the patient group, and a trend toward higher modularity (p = 0.033) and small-world values (p = 0.123) in the HC group.

Discussion

Patients with AN showed differences in hubs distribution, providing evidence of the presence of a different functional architectural backbone in this group. Since some correlation emerged between different degree values of nodes and differences in volumes, further longitudinal studies are warranted to better understand the role of malnutrition on brain network architecture. The opposite effects of 5-HTTLPR polymorphism on global network characteristics in the two groups suggest an interaction of the short allele and malnutrition in modulating brain network properties.

Goal-directed vs. habitual instrumental behavior during reward processing in anorexia nervosa: an fMRI study

Previous studies have proposed that altered reward processing and elevated cognitive control underlie the etiology of anorexia nervosa (AN). A newly debated notion suggests altered habit learning and an overreliance on habits may contribute to the persistence of AN. In weight-recovered AN patients, we previously found neuroimaging-based evidence for unaltered reward processing, but elevated cognitive control. In order to differentiate between state versus trait factors, we here contrast the aforementioned hypotheses in a sample of acutely underweight AN (acAN) patients. 37 acAN patients and 37 closely matched healthy controls (HC) underwent a functional MRI while performing an established instrumental motivation task. We found no group differences with respect to neural responses during the anticipation or receipt of reward. However, the behavioral response data showed a bimodal distribution, indicative for a goal-directed (gAN) and a habit-driven (hAN) patient subgroup. Additional analyses revealed decreased mOFC activation during reward anticipation in hAN, which would be in line with a habit-driven response. These findings provide a new perspective on the debate regarding the notion of increased goal-directed versus habitual behavior in AN. If replicable, the observed dissociation between gAN and hAN might help to tailor therapeutic approaches to individual patient characteristics.

Addictive behaviors in alcohol use disorder: dysregulation of reward processing systems and maladaptive coping strategies

DSM-5 has included within the substance-related and addictive disorders diagnostic category behavioral addictions, such as gambling disorder. Some scholars also considered ICD-11 compulsive sex as a behavioral addiction. Furthermore, an addiction model of dysfunctional eating behaviors has been proposed. Consistently, the existence of common addiction mechanisms related to substance and non-substance related disorders has been hypothesized. Nevertheless, this approach was called into question, especially considering alternative processes which might be implicated in such conditions. This study aims to compare these opposite theoretical positions concerning substance- and nonsubstance related disorders, investigating the latent structure of addictive behaviors among alcohol use disorder (AUD) individuals. Addictive behaviors were self-reported assessed using the Shorter PROMIS Questionnaire (SPQ). We recruited 456 (59.2% male; 40.8% female) AUD treatment-seeking patients. Two latent structures were tested using a confirmatory factor analytic approach. We compared a one-factor (i.e., common addiction mechanisms) with a two-factor solution (i.e., dysregulation of reward processing systems and maladaptive coping strategies). The two-factor solution showed adequate goodness-of-fit indexes. Specifically, dysregulation of the reward processing systems dimension predicted the SPQ illicit and prescription drugs, gambling, and sex subscales. Conversely, the maladaptive coping strategies dimension predicted the SPQ compulsive buying, binge eating and food restriction subscales. The latent dimensions significantly correlated with each other. Compulsive sex might be preliminarily considered as a behavioral addiction. AUD individuals might show complex patterns of maladaptive behaviors functionally related to different latent processes. Differential treatment approaches are suggested to treat these conditions.

A systematic review of blood-based serotonergic biomarkers in Bulimia Nervosa

Bulimia Nervosa (BN) is a serious eating disorder, which affects 0.8-2.9% of the young population. The etiology is unknown and biomarkers would support in understanding the pathophysiology of BN, and in identifying BN patients that may benefit from medical treatment. This systematic review aims to answer whether (a) BN deviate from healthy controls in terms of serotonin (5-HT) biomarkers in blood, and whether (b) blood-based 5-HT biomarkers could be used to tailor psychopharmacological treatment in BN. A literature search using PubMed, PsycINFO and Embase was done using the following search terms: "Bulimia Nervosa" AND "serotonin" AND "blood" OR "plasma" OR "serum". 32 studies were included in this systematic review. Several biomarkers and challenge tests were identified and all studies described an association with BN and dysregulation of the 5-HT system compared to healthy controls. Several studies pointed to an association also to borderline symptoms in BN. BN deviate from healthy controls in terms of 5-HT biomarkers in blood supporting an abnormal 5-HT system in BN. 5-HT biomarkers and associated methods could be used to tailor treatment in BN although as yet, most tests described are unpractical for bedside use.

Altered thalamo–cortical and occipital–parietal– temporal–frontal white matter connections in patients with anorexia and bulimia nervosa: a systematic review of diffusion tensor imaging studies

BACKGROUND

Anorexia nervosa and bulimia nervosa are complex mental disorders, and their etiology is still not fully understood. This paper reviews the literature on diffusion tensor imaging studies in patients with anorexia nervosa and bulimia nervosa to explore the usefulness of white matter microstructural analysis in understanding the pathophysiology of eating disorders.

METHODS

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to identify diffusion tensor imaging studies that compared patients with an eating disorder to control groups. We searched relevant databases for studies published from database inception to August 2018, using combinations of select keywords. We categorized white matter tracts according to their 3 main classes: projection (i.e., thalamo–cortical), association (i.e., occipital–parietal–temporal–frontal) and commissural (e.g., corpus callosum).

RESULTS

We included 19 papers that investigated a total of 427 participants with current or previous eating disorders and 444 controls. Overall, the studies used different diffusion tensor imaging approaches and showed widespread white matter abnormalities in patients with eating disorders. Despite differences among the studies, patients with anorexia nervosa showed mainly white matter microstructural abnormalities of thalamo–cortical tracts (i.e., corona radiata, thalamic radiations) and occipital–parietal–temporal–frontal tracts (i.e., left superior longitudinal and inferior fronto-occipital fasciculi). It was less clear whether white matter alterations persist after recovery from anorexia nervosa. Available data on bulimia nervosa were partially similar to those for anorexia nervosa.

LIMITATIONS

Study sample composition and diffusion tensor imaging analysis techniques were heterogeneous. The number of studies on bulimia nervosa was too limited to be conclusive.

CONCLUSION

White matter microstructure appears to be affected in anorexia nervosa, and these alterations may play a role in the pathophysiology of this eating disorder. Although we found white matter alterations in bulimia nervosa that were similar to those in anorexia nervosa, white matter changes in bulimia nervosa remain poorly investigated, and these findings were less conclusive. Further studies with longitudinal designs and multi-approach analyses are needed to better understand the role of white matter changes in eating disorders.

Reconceptualizing anorexia nervosa

Anorexia nervosa (AN) has one of the highest mortality rates of any psychiatric disorder. Treatments are often ineffective and relapse is common. Most research attempting to understand the underlying causes and maintenance factors of AN has focused on environmental contributions, yet there is much to be explored in terms of biological risk and maintenance factors. In this paper, we focus primarily on AN research related to genetics and the complex microbial community in the gut (intestinal microbiota), and how these impact our conceptualization of this disorder. Emerging research identifying significant negative genetic correlations between AN and obesity suggests that the conditions may represent 'metabolic bookends'. The identification of underlying biological mechanisms may provide both insight into extreme weight dysregulation on both ends of the spectrum and new possible points of entry for AN treatment. Additionally, the reported microbial imbalance (dysbiosis) in the gut microbiota in AN patients, potentially due to a nutrient- and energy-deprived gut environment, implies alterations in functional and metabolic capacity of the gut microbiome. The extent to which AN and obesity can also be considered to be 'microbiome bookends' requires further investigation. Finally, we discuss ongoing and future AN projects exploring the interplay between host genomics, the environment, and cumulative microbial genomes (microbiome) as well as interventions at the microbial and gut level.

The posited effect of positive affect in anorexia nervosa: Advocating for a forgotten piece of a puzzling disease

Anorexia nervosa (AN) is a complex and life-threatening eating disorder. Current models of AN onset and maintenance have largely focused on the role of negative affect, while fewer models have described the role of positive affect (PA). Given that these theoretical models have informed current treatment approaches, and that treatment remains minimally effective for adults with AN, we advocate that targeting PA is one avenue for advancing maintenance models and by extension, treatment. We specifically propose that AN may arise and be chronically and pervasively maintained as a function of dysregulated PA in response to weight loss and weight loss behaviors (e.g., restriction, excessive exercise), to a degree that is not accounted for in existing models of AN. We present evidence from multiple domains, including biological, behavioral, and self-report, supporting the hypothesis that PA dysregulation in AN contributes to the maintenance of the disorder. We conclude with several specific avenues for treatment development research as well as a call for future work elucidating the biological correlates of PA.

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.

Nutritional Management and Outcomes in Malnourished Medical Inpatients: Anorexia Nervosa

BACKGROUND

Anorexia Nervosa (AN) is a psychiatric disorder characterised by a physical and psychosocial deterioration due to an altered pattern on the intake and weight control. The severity of the disease is based on the degree of malnutrition. The objective of this article is to review the scientific evidence of the refeeding process of malnourished inpatients with AN; focusing on the clinical outcome.

METHODS

We conducted an extensive search in Medline and Cochrane; on April 22; 2019; using different search terms. After screening all abstracts; we identified 19 papers that corresponded to our inclusion criteria.

RESULTS

The article focuses on evidence on the characteristics of malnutrition and changes in body composition; energy and protein requirements; nutritional treatment; physical activity programmes; models of organisation of the nutritional treatment and nutritional support related outcomes in AN patients.

CONCLUSION

Evidence-based standards for clinical practice with clear outcomes are needed to improve the management of these patients and standardise the healthcare process.

Dynamic changes in white matter microstructure in anorexia nervosa: findings from a longitudinal study

BACKGROUND

Gray matter (GM) 'pseudoatrophy' is well-documented in patients with anorexia nervosa (AN), but changes in white matter (WM) are less well understood. Here we investigated the dynamics of microstructural WM brain changes in AN patients during short-term weight restoration in a combined longitudinal and cross-sectional study design.

METHODS

Diffusion-weighted images were acquired in young AN patients before (acAN-Tp1, n = 56) and after (acAN-Tp2, n = 44) short-term weight restoration as well as in age-matched healthy controls (HC, n = 60). Images were processed using Tract-Based-Spatial-Statistics to compare fractional anisotropy (FA) across groups and timepoints.

RESULTS

In the cross-sectional comparison, FA was significantly reduced in the callosal body in acAN-Tp1 compared with HC, while no differences were found between acAN-Tp2 and HC. In the longitudinal arm, FA increased with weight gain in acAN-Tp2 relative to acAN-Tp1 in large parts of the callosal body and the fornix, while it decreased in the right corticospinal tract.

CONCLUSIONS

Our findings reveal that dynamic, bidirectional changes in WM microstructure in young underweight patients with AN can be reversed with brief weight restoration therapy. These results parallel those previously observed in GM and suggest that alterations in WM in non-chronic AN are also state-dependent and rapidly reversible with successful intervention.

Factors associated with body dissatisfaction among the Lebanese population

OBJECTIVE

To evaluate the factors associated with body dissatisfaction among the Lebanese population, including sociodemographic characteristics, self-esteem, stress, anxiety, depression, emotional regulation, emotional eating and the adult attachment style.

METHODS

This cross-sectional study, conducted between January and May 2018, enrolled 811 adult participants from all districts of Lebanon. The body dissatisfaction subscale of the eating disorder inventory version 2 (EDI-2) was used to measure body disturbance.

RESULTS

The mean age of the participants was 27.59 ± 11.76 years, with 66.5% females. The final model of the regression analysis showed that a higher binge eating score (Beta = 0.202), being married (Beta = 1.233), having a family history of eating disorders (Beta = 1.933), higher BMI (Beta = 0.076), dieting to lose weight (past 30 days) (Beta = 2.345), receiving comments from the family (Beta = 2.234) and pressure from TV/magazines to lose weight (Beta = 1.320), vomiting or taking laxatives to lose weight (past 30 days) (Beta = 1.861), higher depression (Beta = 0.103) and higher perceived stress (Beta = 0.107) were associated with a higher body dissatisfaction score. However, higher self-esteem (Beta = - 0.246), increased physical activity (Beta = - 0.022) and being divorced (Beta = - 4.226) were significantly associated with a lower body dissatisfaction score.

CONCLUSION

A significant association was found in this current study between the main variables: depression, self-esteem, social anxiety, eating disorders, family and television pressure and body image dissatisfaction.

LEVEL OF EVIDENCE

Level V, cross-sectional descriptive study.

Pharmacologic Treatment of Eating Disorders

Medications are a useful adjunct to nutritional and psychotherapeutic treatments for eating disorders. Antidepressants are commonly used to treat bulimia nervosa; high-dose fluoxetine is a standard approach, but many other antidepressants can be used. Binge eating disorder can be treated with antidepressants, with medications that diminish appetite, or with lisdexamfetamine. Anorexia nervosa does not generally respond to medications, although recent evidence supports modest weight restoration benefits from olanzapine.

Deconstructing value-based decision making via temporally selective manipulation of neural activity: Insights from rodent models

The ability to choose among options that differ in their rewards and costs (value-based decision making) has long been a topic of interest for neuroscientists, psychologists, and economists alike. This is likely because this is a cognitive process in which all animals (including humans) engage on a daily basis, be it routine (which road to take to work) or consequential (which graduate school to attend). Studies of value-based decision making (particularly at the preclinical level) often treat it as a uniform process. The results of such studies have been invaluable for our understanding of the brain substrates and neurochemical systems that contribute to decision making involving a range of different rewards and costs. Value-based decision making is not a unitary process, however, but is instead composed of distinct cognitive operations that function in concert to guide choice behavior. Within this conceptual framework, it is therefore important to consider that the known neural substrates supporting decision making may contribute to temporally distinct and dissociable components of the decision process. This review will describe this approach for investigating decision making, drawing from published studies that have used techniques that allow temporal dissection of the decision process, with an emphasis on the literature in animal models. The review will conclude with a discussion of the implications of this work for understanding pathological conditions that are characterized by impaired decision making.