How We Eat

EATING DISORDERS: PART 1

Also in this Special Report: 

Closing the Research-Practice Gap in Eating Disorders

How Anxiety and Habits Contribute to Anorexia Nervosa

Interoception in Eating Disorders: A Clinical Primer

Eating disorders, including anorexia nervosa, bulimia nervosa, binge eating disorder, and the newly defined avoidant-restrictive food intake disorder (ARFID), affect more than 5% of the population and are associated with high rates of morbidity and functional impairment. The etiology of these behavioral conditions is multifactorial and includes predisposing, precipitating and perpetuating factors.

Genetic vulnerability predisposes at-risk individuals to an eating disorder. Onset can be precipitated by dieting, puberty, exercise, or stressful life events; and as the disorder progresses physiological and neural changes arising from disordered eating and weight control behaviors feed forward to sustain the driven nature of these conditions. This two-part Special Report-beginning in this issue and continuing in the October issue-focuses on several topics ranging from recent research on the underlying neural mechanisms that maintain disordered eating in anorexia nervosa to guidelines on when to refer patients to higher levels of care as well as information on recognizing and treating ARFID.

What, when, and how we eat is controlled by the brain’s mesolimbic reward circuitry and by hormonal and neural gut – brain hunger and satiety signaling. Additionally, stress and sociocultural pressures shape the learning of eating behavior. Dysregulation in these controls of eating is no more apparent than in anorexia nervosa, where goal-directed dieting gradually takes on a compulsive nature and is no longer controlled by the homeostatic or hedonic drives to eat. As dietary restriction and weight control behaviors become progressively driven, affected individuals grow anxious about deviating from their eating and weight-control routines and increasingly unresponsive to escalating negative consequences of their behavior. Indeed, recent research implicates neural circuits relevant to addiction, anxiety disorders, and OCD in anorexia nervosa.

Two articles in this Special Report focus on how understanding the neurobiological and neurocognitive processes underlying anorexia nervosa inform new treatments and improve existing interventions for this challenging condition. Impairments in instrumental learning and a shift from goal-directed to habitual behavior, along with disturbances in approach-avoidance to food may contribute to the disorder’s tenacious persistence. Improved behavioral meal-based strategies that target fear of consuming calorie-dense foods, together with supportive and neurobiologically informed educational patient and family interventions, may help augment existing treatment approaches.

A related article focuses on interoception, the ability to sense and feel what’s going on inside the body and to integrate bodily sensation, cognitive processes, and emotions. Gut dysmotility and visceral hypersensitivity are frequent consequences of starvation and of binge-purge behaviors. Although largely reversible with normalization of eating behavior, altered somatic and visceral sensations may help sustain disordered eating and cognitions during the illness. Disturbances in interoception are also relevant to the heterogeneous group of patients subsumed under the new diagnostic category of ARFID, the focus of another article in this Special Report.

Two articles describe advances in the treatment of eating disorders and personalized care. Pharmacological interventions have only modest effects, and over 75% of clinical cases either go undetected or do not receive evidence-based care. The latter favors behaviorally based treatments that target normalizing eating and weight control behaviors. In patients who are underweight, starvation exacerbates cognitive and affective symptoms making weight restoration a treatment imperative.

Across diagnoses and interventions, early behavior change is consistently emerging as an important prognostic indicator. Manualized treatments with the strongest empirical support include family-based treatment (FBT) for adolescent anorexia nervosa and cognitive-behavioral therapy (CBT) for bulimia nervosa and binge eating disorder. With both treatments, shorter courses appear as effective as longer interventions. However, dissemination of these approaches has been slow among general psychiatrists and other mental health practitioners. One of the articles reviews reasons for the poor uptake of existing evidence-based treatments and presents emerging solutions that promise to facilitate training and improve implementation.

Finally, one of the articles spotlights the care of eating disorders in intensive treatment settings. Most specialty programs employ a structured behavioral protocol, supervised meals, multidisciplinary team support, and group therapies that emphasize recovery-oriented behavior change, and weight restoration for patients who are underweight.

For individuals with anorexia nervosa, body mass index at program discharge is correlated with risk of relapse. Approximately 50% of fully weight-restored patients achieve recovery. Whenever possible, meal-based nutritional rehabilitation is preferable to nasogastric feeding. Despite historical concerns regarding risk of refeeding syndrome, recent literature supports the safety and effectiveness of higher calorie diets and faster rates of weight gain on the order of 3 to 4 pounds a week as safe and effective when administered in the setting of close medical monitoring and prompt correction of hypophosphatemia and other glucose and electrolyte imbalances. Faster rates of weight gain are important as they help shorten both time in higher level of care treatment settings and the high cost of 24-hour daily specialty care.

We hope readers will find the articles in this Special Report on eating disorders a helpful update for formulating cases, talking to patients and improving management of these complex behavioral disorders. Eating disorders are common, making knowledge of diagnosis and management as well as basic familiarity with first-line interventions of importance for all psychiatrists. Treating eating disorders can feel challenging because patients are typically ambivalent about changing their behavior; however, it is also rewarding, as full recovery is possible even in the most chronically and severely ill patients.

Disclosures:

Dr Guarda is the Stephen and Jean Robinson Associate Professor of Eating Disorders and Associate Professor of Psychiatry and Behavioral Sciences, Johns Hopkins School of Medicine, Baltimore, MD. She reports that she receives research funding from the Klarman Family Foundation.