Learned food aversion: A component of anorexia syndromes.

Abstract

Several syndromes that have been characterized in terms of anorexia or appetite loss may actually be due, at least in part, to specific food aversion learning. Evidence reviewed here indicates that a number of experimental treatments, such as tumor implant and subdiaphragmatic vagotomy, that lead to anorexia in laboratory animals also lead to the development of specific aversions to the single available diet. These aversions appear to be responsible for a significant proportion of the ensuing reduction in food intake and body weight. The case for learned food aversions as a contributing factor in clinical problems of appetite loss is more speculative. However, there are certain clinical situations that provide the expected conditions for significant food aversion learning. A careful examination of dietary patterns of patients with these disorders is proposed as a first step toward evaluating the hypothesis that aversion learning is involved in the etiology or maintenance of clinically important anorexia.The physiological mechanisms regulating food intake have been the focus of productive investigation over the past two decades. One goal of this research has been to enhance our understanding of basic mechanisms of energy regulation and to apply this knowledge to the treatment of clinical disorders of appetite. Much of this work has been directed at identifying the causes of obesity and developing effective treatments. However, the loss of appetite and weight is also a significant and prevalent medical problem that arises in a wide variety of clinical situations. There has, to date, been relatively little success in understanding the pathophysiology of serious appetite and weight loss, and treatment has depended on relatively drastic measures such as prolonged intravenous or intragastric feeding. Interventions grounded in an understanding of the mechanisms by which undernutrition develops could, in theory, offer promise of improved outcome.In general, the study of the physiological mechanisms responsible for the regulation of appetite has delimited one research domain. A separate line of inquiry has been the study of conditioned taste aversions, with an emphasis on defining basic Pavlovian conditioning mechanisms (Barker, Best, & Domjan, 1977). Because these two areas of investigation differ markedly in focus, there has been relatively little interchange between them. However, in both types of studies, a change in ingestive behavior in response to an experimental manipulation is the main dependent variable. Therefore, it is reasonable to explore the potential contribution of taste aversion learning to the development of appetite and weight loss.In this article we will argue that several syndromes character-

Children's recognition of time in the causes and cures of physical and emotional reactions to illnesses and injuries

“…There may also be other contexts in which children can appreciate a delay between a cause and illness onset. For example, in the animal learning literature, although classical conditioning usually occurs only if there is a very short time lag between two stimuli, animals can form an association between a novel taste and illness after a much longer delay (Bernstein & Borson, 1986). Although children expect illness to occur immediately after the causal event, they may nonetheless be able to learn that a longer delay is possible, especially in the domain of food.…”

Conceptual Challenges in Evolutionary Psychology

“…For example, food aversions are notoriously easy to acquire, even when the time interval between ingestion and illness is quite long (Bernstein & Borson, 1986;Etscorn & Stephens, 1973;Garcia, Brett, & Rusiniak, 1989;Logue, 1988). Early learning theories rested on the assumption that an association could be made between~ny two stimuli through repeated pairings, yet it soon became apparent that some associations were learned more readily than others.…”

Classical Conditioning: Still Going Strong

“…There is speculation that specific food aversions play a role in several syndromes that are (often) characterized by anorexia (canceranorexia; anorexia nervosa; depression). Though certainly thought provoking, these ideas (Bernstein and Borson, 1986) still remain untested hypotheses. In cases where food aversions are acquired through CC and are maintained by avoidance of the food, conditioning theory predicts extinction of aversion after repeated CS exposure.…”