Table 3 Studies that reported unchanged dopaminergic state in binge eating

Yilmaz et al. 66

Case–control

Examine if certain variants of the COMT genetic markers (rs6269, rs4633, rs4818 and rs4680) are more common in BN versus controls

240 women with purging subtype BN (age: 26.0 ± 7.0; BMI: 22.2 ± 3.4)

Ethnicity-matched female controls

Among BN patients, 20 had ADHD

Exclusion: a maximum lifetime BMI ≥ 35 kg/m2, history of a psychotic episode, history of bipolar disorder, diabetes, thyroid or endocrine disorder

Eating disorder examination

Blood lymphocyte DNA was extracted using the high-salt method

There were no differences between bulimic women and nonpsychiatric controls in terms of genotype, allele, and haplotype frequencies for any of the four COMT markers

COMT Val158 allele was overrepresented and the medium-activity haplotype was underrepresented in BN with childhood ADHD history

Yilmaz et al. 63

Case–control

To compare DRD4 hypofunctional allele frequencies in BN when compared with controls

157 female with purging type BN (age: 26.0 ± 7.1; BMI: 22.1 ± 3.2)

157 ethnicity-matched female controls

Among BN patients, 19 had ADHD

Eating disorder examination

Blood lymphocyte DNA was extracted using the high-salt method

There were no differences between BN probands and controls in terms of DRD4 allele frequencies

34.2% of BN probands with childhood ADHD carried at least one copy of 2R or 7R allele. In contrast, only 14% of BN probands who did not have childhood ADHD carried one or both alleles

Groleau et al. 85

Case–control

Examine the associations between DRD2 methylation and bulimic eating disorder

Of the 52 women with a bulimia spectrum disorder (age: 24.7 ± 5.7; BMI: 22.8 ± 4.4), 63.5% BN-Purging subtype, 3.8% for BN-Non Purging subtype, and 32.7% an Eating Disorder Not Otherwise Specified

67.3% were using a psychoactive medication, 8 had bipolar disorder, 14 had childhood sexual abuse, 23 had childhood physical abuse

19 female controls without childhood maltreatment (age: 23.7 ± 4.6; BMI: 22.4 ± 2.8)

Eating disorder examination

The sequence of DRD2 was identified using UCSC Genome Browser Assembly February 2009

No overall difference as to DRD2 methylation between non-eating disorder and bulimia spectrum disorder groups

Bulimia/Borderline Personality Disorder group had a significantly higher mean methylation than did either Bulimia/no-Borderline Personality Disorder or no eating disorder groups

Bulimia/Childhood Sexual Abuse women have a significantly higher mean methylation than did No Eating Disorder women

Dodds et al. 54

Randomized, double-blind, placebo-controlled, two-way cross over design

Investigate the effects of the selective dopamine D3 receptor antagonist GSK598809 on brain activation to food images in a sample of binge and emotional eating obese and overweight subjects

26 obese participants who reported binge eating behaviors and emotional eating (15 male, 11 female; age: 35.1 ± 7.1; BMI: 32.7 ± 3.7)

Minimum 1 episode/week binge eating behavior

Had no personal or family history of psychiatric disorders, had no history of substance abuse, had no history of eating disorders, had reported no significant weight loss (or gain)

Participants received either GSK598809 (175 mg capsule) or placebo

Brain activities to high-fat or general food images were measured by fMRI, which was performed approximately 3 h post dose

No significant effect of GSK598809 on activation to food images or to high calorie food images in any of the brain regions: amygdala, insula, ventral striatum, caudate, putamen, midbrain and hypothalamus

The effect of GSK598809 on brain activation to food images, or more specifically to high calorie food images, did not correlate significantly with scores on any of the personality/eating behavior questionnaires

There was no effect of GSK598809 on subjective feelings of hunger and craving

Lardeux et al. 82

Animal study

Test whether injection of dopamine receptor antagonists into the accumbens reduced consumption of a sweet high-fat liquid in rats with and without a history of intermittent binge access to the liquid

Male Long–Evans rats

Rats were divided in three group, the intermittent access (binge) group (n = 93) and two control groups: the water access group (n = 83) and the continuous access group (n = 38)

Rats received injection of vehicle and dopamine D1 or D2 receptor antagonist

The injection of dopamine D1 and D2 receptor antagonist in the nucleus accumbens core or shell did not impact the consumption of food in any groups