Obesity and Blunted Dorsal Striatal Response to Eating

The amount of dopamine release in the dorsal striatum is correlated with pleasure from eating, and obese individuals have fewer dopamine D₂ receptors than do lean individuals. Some researchers have hypothesized that in obese people, overeating compensates for hypofunctioning dopamine reward circuitry. Obesity and reduced numbers of D₂ receptors also have been linked with the A1 allele of the TaqIA polymorphism of the dopamine D₂ receptor gene (DRD2). These investigators hypothesized that striatal response to a highly palatable food would be blunted in obese individuals, with a stronger effect in those with the A1 allele than in those without it.

The researchers measured body-mass index (BMI) and assessed striatal activation on functional MRI…