Physician Gene-Jack Wang and psychiatrist Nora Volkow of Brookhaven, along with their colleagues, injected a mixed group of obese people and those of normal weight with a radioactive chemical that binds to dopamine receptors, then examined the subjects' brains with PET scans. Obese people had fewer receptors overall, and the disparity increased with a higher body-mass index. The same researchers had previously observed a similar paucity of dopamine receptors in scans of the brains of drug addicts. As with cocaine or heroin, eating causes the body to produce dopamine. In normal brains, routine pleasures such as watching a sunset also release the chemical.
Researchers hypothesize that brains containing fewer receptors are less sensitive to everyday joys.
If other stimuli aren't powerful enough to activate those reward circuits, you're going to get something that will, and food will do it. Drugs that boost the production of dopamine show promise of breaking the cycle of overeating in animal tests. Such treatments are far from FDA approval, however, and Volkow cautions that human behavior may limit their efficacy. The Walt Disney Company. Back to Homepage .