Discounting of delayed and probabilistic rewards by women with and without binge eating disorder

Obese individuals with binge eating disorder (BED) exhibit more general and eating-disordered psychopathology than obese individuals without BED. Binge eating also impedes weight-loss efforts, already difficult in an obese population. A better basic understanding of binge eating and obesity is needed to refine treatments for both conditions. Discounting, an experimental paradigm that examines changes in the value of delayed or uncertain outcomes, may provide an objective assessment of impulsive behavior. Impulsivity may perpetuate binge eating, but discounting tasks have never been evaluated with eating disordered individuals. A discounting procedure could help differentiate individuals with eating/weight problems from controls in terms of impulsive behavior and the relative value of rewards. This study compared discounting rates of food, money, sedentary activity, and a control variable among 30 obese women with BED, 30 obese women without BED, and 30 normal-weight controls. Relations were examined between questionnaire measures of psychopathology and discounting rates; and between obesity and binge eating and discounting rates. The BED group discounted delayed and probabilistic rewards overall more steeply (impulsively) than Obese and Controls, with no difference between the latter two groups. Further, the BED group discounted delayed food more steeply than money as compared to Obese and Controls. Delay and probability discounting rates were correlated with general psychopathology but not eating disorder psychopathology, obesity, binge eating, or self-report impulsivity questionnaires. These results indicate that women with BED choose rewards more impulsively, especially with food, and are more risk averse, than obese or normal-weight women, and obese and normal-weight women do not differ in their impulsive decision-making. General psychopathology, but not scores on impulsivity questionnaires, was correlated with discounting rates, portending further research into the relationship between impulsive decision-making and other psychological disorders, and providing further support of the multidimensionality of impulsivity. The more impulsive decision-making by the BED group suggests a temperamental difference in this eating disorder that cannot be accounted for by the concomitant obesity. Future research should examine the predictive power of discounting within individuals with BED and its amenability with psychological treatment, which also would aid in developing prevention and treatment programs for other impulse-control disorders...