EATING DISORDERS: PART 1
Also in this Special Report:
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.
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.