Enhanced striatal dopamine release during food stimulation in binge eating disorder

Abstract

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.

Figure 1

Flow chart of the study. PET, positron emission tomography.

Figure 2

Distribution volume ratio image [¹¹C]raclopride at level of striatum for one of the binge eaters and one of the nonbinge eaters for four scanning conditions: neutral stimulation with oral placebo, neutral stimulation with oral methylphenidate (MPH), food stimulation with oral placebo and food stimulation with oral MPH. The images are scaled with respect to the maximum distribution volume ratio value of the binge eater obtained on neutral stimulation with oral placebo. The images are presented by using the rainbow scale, where red represents the highest value and violet represents the lowest value. Binding of [¹¹C]raclopride is lowest during the food stimulation with oral MPH in the binge eater.

Figure 3

Correlation between dopamine release (changes in nondisplaceable binding potential (BP_ND)) in the caudate nucleus of all subjects under food_MPH condition with scores of the Gormally Binge Eating Scale (n = 18, r = 0.49, P < 0.03). MPH, methylphenidate.