Plain language summary
While food intake is critical for survival, adaptive decision-making can be altered through various mechanisms and eventually lead to disordered eating patterns. Feeding behaviour is dependent on homeostatic rules, motivational drives, biological predispositions and external stressors. This complex web elucidates how humans can decide to satisfy or abstain from hunger cues, and the underlying mechanisms of this behaviour have been increasingly explored. This review summarises the overall neural circuitry in restrictive food choice and binge eating. Serotonergic systems play a key role in eating disorders because they are involved in responses to stress, emotions and feeding behaviour. The decision to overeat or abstain from eating is a reward, and this goal-directed and persistent behaviour mirror some aspects of drug dependence. This review found that voluntary processes in the nervous system could be modified to predominate over homeostatic control of hunger. Eating disorders may emerge when serotonin neurons reach their limit of adaptive capacities, potentially to the extent of compromised survival. This study provides a basis for developing more effective interventions for this population.
Abstract
Adaptive decision making to eat is crucial for survival, but in anorexia nervosa, the brain persistently supports reduced food intake despite a growing need for energy. How the brain persists in reducing food intake, sometimes even to the point of death and despite the evolution of multiple mechanisms to ensure survival by governing adaptive eating behaviors, remains mysterious. Neural substrates belong to the reward-habit system, which could differ among the eating disorders. The present review provides an overview of neural circuitry of restrictive food choice, binge eating, and the contribution of specific serotonin receptors. One possibility is that restrictive food intake critically engages goal-directed (decision making) systems and "habit," supporting the view that persistent caloric restriction mimics some aspects of addiction to drugs of abuse. SIGNIFICANCE STATEMENT An improved understanding of the neural basis of eating disorders is a timely challenge because these disorders can be deadly. Up to 70 million of people in the world suffer from eating disorders. Anorexia nervosa affects 1-4% of women in United States and is the first cause of death among adolescents in Europe. Studies relying on animal models suggest that decision making to eat (or not) can prevail over actual energy requirements due to emotional disturbances resulting in abnormal habitual behavior, mimicking dependence. These recent studies provide a foundation for developing more specific and effective interventions for these disorders.
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