Successful pharmacotherapy for the treatment of severe feeding aversion with mechanistic insights from cross-species neuronal remodeling

Systematic review of pharmacological treatments that reduce conditioned taste aversions in rodents: A potential animal model of pediatric feeding disorder and avoidant/restrictive food intake disorder (ARFID)

Avoidant/restrictive food intake disorder (ARFID) is diagnosed when food avoidance leads to clinically significant nutritional, weight/growth, or psychosocial impairment. As many as 81.5% of children and adolescents diagnosed with ARFID have a history of a medical condition associated with pain, fatigue, or malaise. ARFID is diagnosed and treatment begins after the medical condition is resolved but food avoidance remains. Effective treatment involves repeated exposure to eating food and related stimuli aimed at creating inhibitory learning to counteract learned fears and aversions. Treatment usually involves positive reinforcement of food approach behavior and escape extinction/response prevention to eliminate food avoidant behavior. To shed light on the neural mechanisms that may maintain ARFID and to identify candidate pharmacological treatments for adjuncts to behavioral interventions, this paper systematically reviews research on drug treatments that successfully reduce conditioned taste aversions (CTA) in animal models by disrupting reconsolidation or promoting extinction. The mechanism of action of these treatments, brain areas involved, and whether these CTA findings have been used to understand human eating behavior are assessed. Collectively, the results provide insight into possible neural mechanisms associated with resuming oral intake following CTA akin to the therapeutic goals of ARFID treatment and suggest that CTA animal models hold promise to facilitate the development of interventions to prevent feeding problems. The findings also reveal the need to investigate CTA reduction in juvenile and female animals and show that CTA is rarely studied to understand disordered human feeding even though CTA has been observed in humans and parallels many of the characteristics of rodent CTA.

A scoping review of psychological interventions and outcomes for avoidant and restrictive food intake disorder (ARFID)

OBJECTIVE

This scoping review identifies and describes psychological interventions for avoidant restrictive food intake disorder (ARFID) and summarizes how outcomes are measured across such interventions.

METHOD

Five databases (Cochrane, Embase, Medline, PsycInfo, Web of Science) were searched up to December 22, 2022. Studies were included if they reported on psychological interventions for ARFID. Studies were excluded if participants did not have an ARFID diagnosis and if psychological interventions were not delivered or detailed.

RESULTS

Fifty studies met inclusion criteria; almost half were single-case study designs (23 studies) and most studies reported on psychological interventions for children and adolescents with ARFID (42 studies). Behavioral interventions (16 studies), cognitive-behavioral therapy (10 studies), and family therapy (5 studies), or combinations of these therapeutic approaches (19 studies) were delivered to support patients with ARFID. Many studies lacked validated measures, with outcomes most commonly assessed via physical health metrics such as weight.

DISCUSSION

This review provides a comprehensive summary of psychological interventions for ARFID since its introduction to the DSM-5. Across a range of psychological interventions and modalities for ARFID, there were common treatment components such as food exposure, psychoeducation, anxiety management, and family involvement. Currently, studies reporting on psychological interventions for ARFID are characterized by small samples and high levels of heterogeneity, including in how outcomes are measured. Based on reviewed studies, we outline suggestions for clinical practice and future research.

PUBLIC SIGNIFICANCE

Avoidant restrictive food intake disorder (ARFID) is an eating disorder characterized by avoidance or restriction of food due to fear, sensory sensitivities, and/or a lack of interest in food. We reviewed the literature on psychological interventions for ARFID and the outcomes used to measure change. Several psychological interventions have been developed and applied to patients with ARFID. Outcome measurement varies widely and requires further development and greater consensus.

Nutritional and feeding challenges in aerodigestive patients

PURPOSE OF REVIEW

Aerodigestive disorders encompass conditions that affect both the airway and gastrointestinal tract. These include conditions such as acquired and congenital defects of the airway and esophagus as well as neuromuscular disorders. Patients often suffer from dysphagia, aspiration, and respiratory disorders. This article will provide a review of current practices in the management of feeding disorders, oropharyngeal dysphagia, and nutritional support in the aerodigestive population.

RECENT FINDINGS

Oral aversion, aspiration, and feeding-tube dependence are all commonly encountered problems in the aerodigestive population. Intensive inpatient and outpatient programs along with use of appetite stimulants and psychotropic medications may help to improve feeding-related disorders. Aspiration affects many patients and requires close monitoring of clinical symptoms along with routine assessment with video fluoroscopy. Developments in blenderized feeds and formula supplementation have also provided new options for patients with feeding intolerance.

SUMMARY

Patients with aerodigestive disorders require complex medical care, and multidisciplinary teams are the most effective in addressing their medical needs. Advances in feeding, occupational, and pharmacologic therapy have allowed healthcare providers to better address the needs of these patients.

Current evidence for avoidant restrictive food intake disorder: Implications for clinical practice and future directions

Background

ARFID (avoidant restrictive food intake disorder) is a relatively new diagnostic term covering a number of well-recognised, clinically significant disturbances in eating behaviour unrelated to body weight/shape concerns. Its phenotypic heterogeneity combined with much about the condition remaining unknown, can contribute to uncertainties about best practice. While other reviews of the evidence base for ARFID exist, few specifically target health care professionals and implications for clinical practice.

Methods

A narrative review was conducted to synthesise the findings of ARFID papers in scientific journals focussing on four key areas relevant to clinical practice: prevalence, assessment and characterisation of clinical presentations, treatment, and service delivery. Freely available online databases were searched for case studies and series, research reports, review articles, and meta-analyses. Findings were reviewed and practice implications considered, resulting in proposed clinical recommendations and future research directions.

Results

We discuss what is currently known about the four key areas included in this review. Based on available evidence as well as gaps identified in the literature, recommendations for clinical practice are derived and practice-related research priorities are proposed for each of the four of the areas explored.

Conclusion

Prevalence studies highlight the need for referral and care pathways to be embedded across a range of health care services. While research into ARFID is increasing, further studies across all areas of ARFID are required and there remains a pressing need for guidance on systematic assessment, evidence-based management, and optimal service delivery models. Informed clinical practice is currently predominantly reliant on expert consensus and small-scale studies, with ongoing routine clinical data capture, robust treatment trials and evaluation of clinical pathways all required. Despite this, a number a positive practice points emerge.

Intensive Multidisciplinary Feeding Intervention for High-Risk Infants

Infants born premature or other medical complex infants are at high risk for developing long-term feeding problems that extends beyond infancy. Intensive multidisciplinary feeding intervention (IMFI) represents the standard of care for children with chronic and severe feeding issues, with a profession team that should involve, at a minimum, psychology, medicine, nutrition, and feeding skill expertise. IMFI seems to hold benefit for preterm and medically complex infants; however, there remains a need to develop and investigate new therapeutic pathways to reduce the number of patients who likely require this level of care.

Assessment and Treatment of Avoidant/Restrictive Food Intake Disorder

PURPOSE OF REVIEW

To review the literature pertaining to the assessment and treatment of avoidant/restrictive food intake disorder (ARFID) ten years following its introduction to DSM-5.

RECENT FINDINGS

Several structured clinical interviews for assessing ARFID have been developed, each with its own strengths and limitations. There is no clear leading self-report measure for tracking treatment progress and outcome in ARFID. Medical assessment is comprised of examining anthropometrics, vitamin deficiencies, and other comorbidities. To date, several studies have reported on cognitive behavioral therapy, family-based treatment, and other approaches to the treatment of ARFID. These treatments appear promising; however, they rely on data from clinical case series and very small randomized controlled trials. Several promising assessments and treatments for ARFID are in the early stages of research. Yet, controversies remain. These include (a) overlap with criteria for pediatric feeding disorder; (b) the optimal method for assessing nutrient deficiencies; (c) disciplines involved in treatment. Future research innovation is necessary to improve the psychometric properties of ARFID assessments and evaluate treatment efficacy with larger samples and randomized designs.

Feeding/Eating problems in children: Who does (not) benefit after behavior therapy? A retrospective chart review

Background

Treating disordered feeding at a young age reduces risks of future feeding problems, but not all children profit equally; can we define predictors of a worse prognosis?

Objectives

In 252 children, with a mean age of 4; 7 years (SD = 3 years; range 5 months to 17; 10 years), who had undergone behavioral day treatment in the past, several variables were investigated, retrieved from initial consultation (t1) and re-assessed at follow-up (t2).

Method

Logistic regressions were carried out with sex, gastro-intestinal problems, refusal of the first nutrition, syndrome/intellectual disability, Down's syndrome, autism spectrum disorder, comorbidity of medical diseases (other than gastro-intestinal problems), restrictive caloric food intake and selective food intake, as the predictor variables from t1, and age-appropriate food intake at t2 as the dependent variable. The potential role of sensory processing problems was reviewed at t2.

Results

About 73% had improved towards an age-appropriate food intake. Sex (boys), syndrome/intellectual disability, and a lack of varied nutritional intake at t1 were predictors of a worse prognosis. We found a small, but significant correlation between current selective eating patterns and general sensory processing problems.

Conclusion

Feeding disordered children, especially boys, with intellectual disabilities or selective eating patterns are at risk for not achieving an age-adequate food intake at a later age, despite behavioral treatment.

Medial orbitofrontal neurotrophin systems integrate hippocampal input into outcome-specific value representations

In everyday life, we mentally represent possible consequences of our behaviors and integrate specific outcome values into existing knowledge to inform decisions. The medial orbitofrontal cortex (MO) is necessary to adapt behaviors when outcomes are not immediately available-when they and their values need to be envisioned. Nevertheless, neurobiological mechanisms remain unclear. We find that the neuroplasticity-associated neurotrophin receptor tropomyosin receptor kinase B (TrkB) is necessary for mice to integrate outcome-specific value information into choice behavior. This function appears attributable to memory updating (and not retrieval) and the stabilization of dendritic spines on excitatory MO neurons, which led us to investigate inputs to the MO. Ventral hippocampal (vHC)-to-MO projections appear conditionally necessary for value updating, involved in long-term aversion-based value memory updating. Furthermore, vHC-MO-mediated control of choice is TrkB dependent. Altogether, we reveal a vHC-MO connection by which specific value memories are updated, and we position TrkB within this functional circuit.

Roles for the gut microbiota in regulating neuronal feeding circuits

The gut microbiota has the capacity to affect host appetite via intestinal satiety pathways, as well as complex feeding behaviors. In this Review, we highlight recent evidence that the gut microbiota can modulate food preference across model organisms. We discuss effects of the gut microbiota on the vagus nerve and brain regions including the hypothalamus, mesolimbic system, and prefrontal cortex, which play key roles in regulating feeding behavior. Crosstalk between commensal bacteria and the central and peripheral nervous systems is associated with alterations in signaling of neurotransmitters and neuropeptides such as dopamine, brain-derived neurotrophic factor (BDNF), and glucagon-like peptide-1 (GLP-1). We further consider areas for future research on mechanisms by which gut microbes may influence feeding behavior involving these neural pathways. Understanding roles for the gut microbiota in feeding regulation will be important for informing therapeutic strategies to treat metabolic and eating disorders.

Cognitive-behavioral therapy for avoidant/restrictive food intake disorder: Feasibility, acceptability, and proof-of-concept for children and adolescents

OBJECTIVE

Little is known about the optimal treatment of avoidant/restrictive food intake disorder (ARFID). The purpose of this study was to evaluate feasibility, acceptability, and proof-of-concept for cognitive-behavioral therapy for ARFID (CBT-AR) in children and adolescents.

METHOD

Males and females (ages 10-17 years) were offered 20-30 sessions of CBT-AR delivered in a family-based or individual format.

RESULTS

Of 25 eligible individuals, 20 initiated treatment, including 17 completers and 3 dropouts. Using intent-to-treat analyses, clinicians rated 17 patients (85%) as "much improved" or "very much improved." ARFID severity scores (on the Pica, ARFID, and Rumination Disorder Interview) significantly decreased per both patient and parent report. Patients incorporated a mean of 16.7 (SD = 12.1) new foods from pre- to post-treatment. The underweight subgroup showed a significant weight gain of 11.5 (SD = 6.0) pounds, moving from the 10th to the 20th percentile for body mass index. At post-treatment, 70% of patients no longer met criteria for ARFID.

DISCUSSION

This is the first study of an outpatient manualized psychosocial treatment for ARFID in older adolescents. Findings provide evidence of feasibility, acceptability, and proof-of-concept for CBT-AR. Randomized controlled trials are needed.

Childhood Avoidant/Restrictive Food Intake Disorder: Review of Treatments and a Novel Parent-Based Approach

Avoidant/Restrictive food intake disorder (ARFID) is characterized by dietary restrictions that are not based on weight or shape concerns but that result in marked interference in feeding, growth, or psychosocial functioning (American Psychiatric Association, 2013; Eddy et al., 2019). The aim of the current article was to review available reports of treatment for childhood ARFID published since its inclusion in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM), and to introduce a novel parent-based treatment for child ARFID through a case presentation. Empirical support for psychosocial treatments for child ARFID currently stems from two small-scale pilot randomized control trials, one pilot open trial, case reports, case series, and retrospective chart reviews. Treatment approaches for outpatient care generally apply family-based therapy, child-centered cognitive behavioral therapy, or parent-based behavioral approaches. SPACE-ARFID is a novel outpatient parent-based treatment that focuses on parental responses to child problematic eating habits. SPACE-ARFID aims to promote flexibility and adjustment in food related situations. The treatment helps parents to systematically reduce family accommodation, or changes that they make to their own behavior to help their child avoid or alleviate distress related to the disorder, while increasing supportive responses to the child's symptoms.

Avoidant/restrictive food intake disorder: A systematic scoping review of the current literature

Avoidant/restrictive food intake disorder (ARFID) was recently introduced to psychiatric nosology to describe a group of patients who have avoidant or restrictive eating behaviours that are not motivated by a body image disturbance or a desire to be thinner. This scoping review aimed to systematically assess the extent and nature of the ARFID literature, to identify gaps in current understanding, and to make recommendations for further study. Following an extensive database search, 291 unique references were identified. When matched against pre-determined eligibility criteria, 78 full-text publications from 14 countries were found to report primary, empirical data relating to ARFID. This literature was synthesised and categorised into five subject areas according to the central area of focus: diagnosis and assessment, clinical characteristics, treatment interventions, clinical outcomes, and prevalence. The current evidence base supports ARFID as a distinct clinical entity, but there is a limited understanding in all areas. Several possible avenues for further study are indicated, with an emphasis placed on first parsing this disorder's heterogeneous presentation. A better understanding of the varied mechanisms which drive food avoidance and/or restriction will inform the development of targeted treatment interventions, refine screening tools and impact clinical outcomes.

Avoidant/Restrictive Food Intake Disorder

Avoidant/restrictive food intake disorder (ARFID) is a relatively newly introduced diagnostic category within the feeding and eating disorders. This article summarizes current knowledge and clinical practice relating to ARFID in youth. It discusses epidemiology, diagnosis, clinical assessment, treatment interventions, prognosis, and outcome. Gaps in the existing research literature are highlighted, promising avenues of current research signposted, and potentially useful future directions proposed. The article is relevant to clinicians wishing to ensure their practice is based on up-to-date information, as well as researchers interested in furthering knowledge relating to ARFID.

Reward-Related Expectations Trigger Dendritic Spine Plasticity in the Mouse Ventrolateral Orbitofrontal Cortex

An essential aspect of goal-directed decision-making is selecting actions based on anticipated consequences, a process that involves the orbitofrontal cortex (OFC) and potentially, the plasticity of dendritic spines in this region. To investigate this possibility, we trained male and female mice to nose poke for food reinforcers, or we delivered the same number of food reinforcers non-contingently to separate mice. We then decreased the likelihood of reinforcement for trained mice, requiring them to modify action-outcome expectations. In a separate experiment, we blocked action-outcome updating via chemogenetic inactivation of the OFC. In both cases, successfully selecting actions based on their likely consequences was associated with fewer immature, thin-shaped dendritic spines and a greater proportion of mature, mushroom-shaped spines in the ventrolateral OFC. This pattern was distinct from spine loss associated with aging, and we identified no effects on hippocampal CA1 neurons. Given that the OFC is involved in prospective calculations of likely outcomes, even when they are not observable, constraining spinogenesis while preserving mature spines may be important for solidifying durable expectations. To investigate causal relationships, we inhibited the RNA-binding protein fragile X mental retardation protein (encoded by Fmr1), which constrains dendritic spine turnover. Ventrolateral OFC-selective Fmr1 knockdown recapitulated the behavioral effects of inducible OFC inactivation (and lesions; also shown here), impairing action-outcome conditioning, and caused dendritic spine excess. Our findings suggest that a proper balance of dendritic spine plasticity within the OFC is necessary for one's ability to select actions based on anticipated consequences.SIGNIFICANCE STATEMENT Navigating a changing environment requires associating actions with their likely outcomes and updating these associations when they change. Dendritic spine plasticity is likely involved, yet relationships are unconfirmed. Using behavioral, chemogenetic, and viral-mediated gene silencing strategies and high-resolution microscopy, we find that modifying action-outcome expectations is associated with fewer immature spines and a greater proportion of mature spines in the ventrolateral orbitofrontal cortex (OFC). Given that the OFC is involved in prospectively calculating the likely outcomes of one's behavior, even when they are not observable, constraining spinogenesis while preserving mature spines may be important for maintaining durable expectations.

A systematic scoping review of diagnostic validity in avoidant/restrictive food intake disorder

OBJECTIVE

Avoidant/restrictive food intake disorder (ARFID) was introduced as a new diagnosis in the DSM-5. This systematic scoping review explores how ARFID as a diagnostic entity is conceptualized in the research literature and evaluates the diagnostic validity according to the Feighner criteria.

METHOD

A systematic scoping review of papers on ARFID in PubMed/MEDLINE and Web of Science was undertaken, following PRISMA and Joanna Briggs Institute guidelines.

RESULTS

Fifty-one original research publications, 23 reviews and commentaries, and 20 case reports were identified. The use of ARFID as a conceptual category varies significantly within this literature. At this time, the ARFID diagnosis does not fulfil the Feighner criteria for evaluating the validity of diagnostic constructs, the most urgent problem being the demarcation toward other disorders. A three-dimensional model-lack of interest in food, selectivity based on sensory sensitivity, and fear of aversive consequences-is gaining support in the research literature.

DISCUSSION

The introduction of the ARFID diagnosis has undoubtedly increased the recognition of a previously largely neglected group of patients. However, this article points to an inability of the current DSM-5 diagnostic criteria to ensure optimal diagnostic validity, which risks making them less useful in clinical practice and in epidemiological research. To increase the conceptual validity of the ARFID construct, several possible alterations to the current diagnostic criteria are suggested, including a stronger emphasis of the three identified subdomains and further clarifying the boundaries of ARFID.

Feeding and Eating Disorders in Children

This article provides an update based on recently published literature and expert consensus on the current state of knowledge regarding feeding and eating disorders in children aged 2 to 12 years. It covers the 6 main diagnostic categories-pica, rumination disorder, avoidant/restrictive food intake disorder, anorexia nervosa, bulimia nervosa, and binge eating disorder-discussing issues and findings specific to this age group. It highlights the need for ongoing research in a number of key areas, to include improved understanding of etiologic pathways, characterization of presenting disorders, and the development of standardized evidence-based assessment tools and treatment interventions.

Cognitive-behavioral treatment of avoidant/restrictive food intake disorder

PURPOSE OF REVIEW

Avoidant/restrictive food intake disorder (ARFID) was added to the psychiatric nomenclature in 2013, but little is known about its optimal treatment. The purpose of this article is to review the recent literature on ARFID treatment and highlight a novel cognitive-behavioral approach, currently under study.

RECENT FINDINGS

The current evidence base for ARFID treatment relies primarily on case reports, case series, and retrospective chart reviews, with only a handful of randomized controlled trials in young children. Studies in adults are lacking. ARFID treatments recently described in the literature include family-based treatment and parent training; cognitive-behavioral approaches; hospital-based re-feeding including tube feeding; and adjunctive pharmacotherapy. A novel form of outpatient cognitive-behavioral therapy for ARFID (CBT-AR) is one treatment currently under study. CBT-AR is appropriate for children, adolescents, and adults ages 10 years and more; proceeds through four stages across 20-30 sessions; and is available in both individual and family-supported versions.

SUMMARY

There is no evidence-based psychological treatment suitable for all forms of ARFID at this time. Several groups are currently evaluating the efficacy of new psychological treatments for ARFID - particularly, family-based and cognitive-behavioral approaches - but results have not yet been published.

d-Cycloserine facilitates fear extinction in adolescent rats and differentially affects medial and lateral prefrontal cortex activation

Adolescent humans and rodents are impaired in extinguishing learned fear relative to younger and older groups. This impairment could be due to differences in recruitment of medial prefrontal cortex (PFC), orbitofrontal cortex (OFC), or amygdala during extinction. For example, unlike juveniles and adults, adolescent rats do not express extinction-induced increases in phosphorylated mitogen activated protein kinase (pMAPK), a marker of synaptic plasticity, in the medial PFC. The NMDA receptor partial agonist d-cycloserine (DCS) improves extinction retention in adolescent rats. We investigated whether DCS affected recruitment of the PFC and amygdala during extinction by measuring pMAPK-immunoreactive (IR) neurons. Adolescent rats were trained to fear a conditioned stimulus in one context followed by extinction in a second context or equivalent context exposure only (i.e., no extinction). DCS (15 mg/kg, s.c.) or saline was administered systemically immediately after extinction training or context exposure. DCS enhanced extinction learning and this was associated with increased activation of the MAPK signaling pathway in the OFC after extinction training and increased activation in the medial PFC and amygdala at extinction retention. These findings suggest that DCS improves extinction learning in adolescents because it augments OFC contributions to extinction learning, enabling better medial prefrontal contributions to extinction retention.