Sensitivity to the rewarding effects of food and exercise in the eating disorders

The diminished capacity to experience pleasure or reward ("anhedonia") has its biological underpinnings in the mesolimbic dopamine system and is strongly implicated in risk for a variety of addictive behaviors. The present study tested the prediction that patients with anorexia nervosa (AN) would be more anhedonic than those with bulimia nervosa (BN)-a factor that could contribute to their respective avoidance and approach relationship to food. We also tested the idea that anhedonia would be correlated with high-level exercising from the viewpoint that the latter serves as a compensatory behavior for a blunted affect. AN patients of the restrictor subtype (n = 78) and BN patients with no history of AN (n = 76) were included in the regression analyses. Patients were also classified as excessive exercisers or moderate/nonexercisers according to information gathered during a structured clinical interview. Findings were largely supportive of our predictions. AN patients were highly anhedonic compared to BN patients, and excessive exercisers tended to be more anhedonic than those who did not exercise. We discuss the AN-BN differences in capacity for reward/pleasure in the context of the common psychobiological links between the eating disorders and drug and alcohol addiction, and speculate on how these differences might relate to the etiology and pathophysiology of both AN and BN.