Emotional eating phenotype is associated with central dopamine D₂ receptor binding independent of body mass index

PET studies have provided mixed evidence regarding central D₂/D3 dopamine receptor binding and its relationship with obesity as measured by body mass index (BMI). Other aspects of obesity may be more tightly coupled to the dopaminergic system. We characterized obesity-associated behaviors and determined if these related to central D₂ receptor (D₂R) specific binding independent of BMI. Twenty-two obese and 17 normal-weight participants completed eating- and reward-related questionnaires and underwent PET scans using the D₂R-selective and nondisplaceable radioligand (N-[ 11 C]methyl)benperidol. Questionnaires were grouped by domain (eating related to emotion, eating related to reward, non-eating behavior motivated by reward or sensitivity to punishment). Normalized, summed scores for each domain were compared between obese and normal-weight groups and correlated with striatal and midbrain D₂R binding. Compared to normal-weight individuals, the obese group self-reported higher rates of eating related to both emotion and reward (p < 0.001), greater sensitivity to punishment (p = 0.06), and lower non-food reward behavior (p < 0.01). Across normal-weight and obese participants, self-reported emotional eating and non-food reward behavior positively correlated with striatal (p < 0.05) and midbrain (p < 0.05) D₂R binding, respectively. In conclusion, an emotional eating phenotype may reflect altered central D₂R function better than other commonly used obesity-related measures such as BMI.