Enhanced striatal dopamine release during food stimulation in binge eating disorder.

Subjects with binge eating disorder (BED) regularly consume large amounts of food in short time periods. The neurobiology of BED is poorly understood. Brain dopamine, which regulates motivation for food intake, is likely to be involved. We assessed the involvement of brain dopamine in the motivation for food consumption in binge eaters. Positron emission tomography (PET) scans with [(11)C]raclopride were done in 10 obese BED and 8 obese subjects without BED. Changes in extracellular dopamine in the striatum in response to food stimulation in food-deprived subjects were evaluated after placebo and after oral methylphenidate (MPH), a drug that blocks the dopamine reuptake transporter and thus amplifies dopamine signals. Neither the neutral stimuli (with or without MPH) nor the food stimuli when given with placebo increased extracellular dopamine. The food stimuli when given with MPH significantly increased dopamine in the caudate and putamen in the binge eaters but not in the nonbinge eaters. Dopamine increases in the caudate were significantly correlated with the binge eating scores but not with BMI. These results identify dopamine neurotransmission in the caudate as being of relevance to the neurobiology of BED. The lack of correlation between BMI and dopamine changes suggests that dopamine release per se does not predict BMI within a group of obese individuals but that it predicts binge eating.

Test meal intake in obese binge eaters in relation to impulsivity and compulsivity.

OBJECTIVE: Studies have linked increased impulsivity and compulsivity with bulimia nervosa (BN). Less is known about this relationship in binge eating disorder (BED). METHOD: Seventy-nine overweight participants (28 male, 65 females) were classified as BED (n = 22), BE (Subthreshold BED, not meeting full criteria for BED) (n = 21), and non-BED (n = 36). Following an 8-hr fast, participants completed psychological scales to assess impulsivity, compulsivity, and depression. They then consumed a liquid test meal until extremely full. RESULTS: Test meal intake (TMI) was significantly greater for both BED and BE than non-BED participants. Impulsivity and depression scores were significantly higher in BED and BE than in non-BED participants. Men had significantly higher compulsivity scores than women. Impulsivity correlated significantly with TMI, accounting for 16% of the variance. CONCLUSION: There was greater impulsivity in BED and BE, compared with non-BED. Moreover, impulsivity was the best predictor of TMI, and may play a larger role in BE than previously realized.