Upton, NY -- Dopamine, a brain chemical associated with addiction to cocaine, alcohol, and other drugs, may also play an important role in obesity. According to a study by scientists at the U.S. Department of Energy's Brookhaven National Laboratory, obese people have fewer receptors for dopamine, a neurotransmitter that helps produce feelings of satisfaction and pleasure. The findings, which will appear in the February 3, 2001 issue of The Lancet, imply that obese people may eat more to try to stimulate the dopamine "pleasure" circuits in their brains, just as addicts do by taking drugs.
"The results from this study suggest that strategies aimed at improving dopamine function might be beneficial in the treatment of obese individuals," says physician Gene-Jack Wang, the lead scientist on the study.
Brookhaven scientists have done extensive research showing that dopamine plays an important role in drug addiction. Among other things, theyve found that addictive drugs increase the level of dopamine in the brain, and that addicts have fewer dopamine receptors than normal subjects.
"Since eating, like the use of addictive drugs, is a highly reinforcing behavior, inducing feelings of gratification and pleasure, we suspected that obese people might have abnormalities in brain dopamine activity as well," says psychiatrist Nora Volkow, who was also involved in the study.
To test this hypothesis, the scientists measured the number of dopamine receptors in the brains of ten severely obese individuals and ten normal controls. Their method consisted of
giving each volunteer subject an injection containing a radiotracer, a radioactive chemical "tag" designed to bind to dopamine receptors in the brain. Then, the researchers scanned the subjects' brains using a positron emission tomography (PET ) camera. The PET camera picks up the radioactive signal of the tracer and shows where it is bound to dopamine receptors in the brain. The strength of the signal in
Contact: Dennis Tartaglia
DOE/Brookhaven National Laboratory